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Finlayson L, Barnard IRM, McMillan L, Ibbotson SH, Brown CTA, Eadie E, Wood K. Depth Penetration of Light into Skin as a Function of Wavelength from 200 to 1000 nm. Photochem Photobiol 2022; 98:974-981. [PMID: 34699624 DOI: 10.1111/php.13550] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/23/2021] [Indexed: 12/13/2022]
Abstract
An increase in the use of light-based technology and medical devices has created a demand for informative and accessible data showing the depth that light penetrates into skin and how this varies with wavelength. These data would be particularly beneficial in many areas of medical research and would support the use and development of disease-targeted light-based therapies for specific skin diseases, based on increased understanding of wavelength-dependency of cutaneous penetration effects. We have used Monte Carlo radiative transport (MCRT) to simulate light propagation through a multi-layered skin model for the wavelength range of 200-1000 nm. We further adapted the simulation to compare the effect of direct and diffuse light sources, varying incident angles and stratum corneum thickness. The lateral spread of light in skin was also investigated. As anticipated, we found that the penetration depth of light into skin varies with wavelength in accordance with the optical properties of skin. Penetration depth of ultraviolet radiation was also increased when the stratum corneum was thinner. These observations enhance understanding of the wavelength-dependency and characteristics of light penetration of skin, which has potential for clinical impact regarding optimizing light-based diagnostic and therapeutic approaches for skin disease.
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Affiliation(s)
- Louise Finlayson
- SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Isla R M Barnard
- SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Lewis McMillan
- SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Sally H Ibbotson
- Photobiology Unit, Ninewells Hospital, University of Dundee, Dundee, UK
| | - C Tom A Brown
- SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Ewan Eadie
- Photobiology Unit, Ninewells Hospital, NHS Tayside, Dundee, UK
| | - Kenneth Wood
- SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, UK
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McMillan L, O'Mahoney P, Feng K, Zheng K, Barnard IRM, Li C, Ibbotson S, Eadie E, Brown CTA, Wood K. Development of a Predictive Monte Carlo Radiative Transfer Model for Ablative Fractional Skin Lasers. Lasers Surg Med 2020; 53:731-740. [PMID: 33161582 DOI: 10.1002/lsm.23335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 09/28/2020] [Accepted: 10/01/2020] [Indexed: 01/17/2023]
Abstract
It is possible to enhance topical drug delivery by pretreatment of the skin with ablative fractional lasers (AFLs). However, the parameters to use for a given AFL to achieve the desired depth of ablation or the desired therapeutic or cosmetic outcome are hard to predict. This leaves open the real possibility of overapplication or underapplication of laser energy to the skin. In this study, we developed a numerical model consisting of a Monte Carlo radiative transfer (MCRT) code coupled to a heat transfer and tissue damage algorithm. The simulation is designed to predict the depth effects of AFL on the skin, verified with in vitro experiments in porcine skin via optical coherence tomography (OCT) imaging. Ex vivo porcine skin is irradiated with increasing energies (50-400 mJ/pixel) from a CO2 AFL. The depth of microscopic treatment zones is measured and compared with our numerical model. The data from the OCT images and MCRT model complement each other well. Nonablative thermal effects on surrounding tissue are also discussed. This model, therefore, provides an initial step toward a predictive determination of the effects of AFL on the skin. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.
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Affiliation(s)
- Lewis McMillan
- SUPA, School of Astronomy and Physics, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Paul O'Mahoney
- Photobiology Unit, NHS Tayside, Ninewells Hospital, Dundee, DD1 9SY, UK.,The Scottish Photodynamic Therapy Centre, Dundee, DD1 9SY, UK.,School of Medicine, University of Dundee, Dundee, DD1 9SY, UK
| | - Kairui Feng
- School of Engineering, University of Dundee, Dundee, DD1 4HN, UK
| | - Kanheng Zheng
- School of Engineering, University of Dundee, Dundee, DD1 4HN, UK
| | - Isla R M Barnard
- SUPA, School of Astronomy and Physics, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Chunhui Li
- School of Engineering, University of Dundee, Dundee, DD1 4HN, UK
| | - Sally Ibbotson
- Photobiology Unit, NHS Tayside, Ninewells Hospital, Dundee, DD1 9SY, UK.,The Scottish Photodynamic Therapy Centre, Dundee, DD1 9SY, UK.,School of Medicine, University of Dundee, Dundee, DD1 9SY, UK
| | - Ewan Eadie
- The Scottish Photodynamic Therapy Centre, Dundee, DD1 9SY, UK.,School of Medicine, University of Dundee, Dundee, DD1 9SY, UK
| | - C Tom A Brown
- SUPA, School of Astronomy and Physics, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Kenneth Wood
- SUPA, School of Astronomy and Physics, University of St Andrews, St Andrews, KY16 9SS, UK
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Stevenson NK, Brown CTA, Hopkins JM, Dawson MD, Lagatsky AA. Broadly tunable femtosecond pulses around 2.06 µm from a diode-pumped Tm 3+-doped solid-state laser source. Opt Express 2019; 27:11103-11111. [PMID: 31052959 DOI: 10.1364/oe.27.011103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
We report on a broadly tunable diode-pumped femtosecond Tm:LuScO3 laser source around 2.06 µm. Tuning was obtained through the use of a steeply diving birefringent filter, maintaining sub-600 fs pulses over a tuning range of 2019-2110 nm. The minimum pulse duration of 240 fs was recorded at a central wavelength of 2080 nm with an average output power of 93 mW. Higher output coupling of 2% resulted in a narrower tuning range of 2070-2102 nm with generated pulses as short as 435 fs and an average output power of 119 mW at 2090 nm.
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O'Mahoney P, Haigh N, Wood K, Brown CTA, Ibbotson S, Eadie E. A novel light source with tuneable uniformity of light distribution for artificial daylight photodynamic therapy. Photodiagnosis Photodyn Ther 2018; 23:144-150. [PMID: 29920346 DOI: 10.1016/j.pdpdt.2018.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 06/13/2018] [Accepted: 06/15/2018] [Indexed: 01/12/2023]
Abstract
OBJECTIVES Implementation of daylight photodynamic therapy (dPDT) is somewhat limited by variable weather conditions. Light sources have been employed to provide artificial dPDT indoors, with low irradiances and comparable treatment times to dPDT. Uniform light distribution across the target area is desirable in effective treatment planning, particularly for large areas. A novel light source is developed with tuneable direction of light emission in order to meet this challenge. METHODS Wavelength composition of the novel light source is controlled such that the protoporphyrin-IX (PpIX) weighted spectra of both the light source and daylight match. The uniformity of the light distribution is characterised on a flat surface, a model head and a model leg. For context, a typical conventional PDT light source is also characterised. Additionally, the wavelength uniformity across the treatment site is characterised. RESULTS The PpIX-weighted spectrum of the novel light source matches the PpIX-weighted daylight spectrum, with irradiance values within the bounds for effective dPDT. By tuning the direction of light emission, improvements are seen in the uniformity across large anatomical surfaces. Wavelength uniformity is discussed. CONCLUSIONS We have developed a light source that addresses the challenges in uniform, multiwavelength light distribution for large area artificial dPDT across curved anatomical surfaces.
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Affiliation(s)
- Paul O'Mahoney
- Photobiology Unit, NHS Tayside, Ninewells Hospital, Dundee, UK; The Scottish Photodynamic Therapy Centre, Dundee, UK; School of Medicine, University of Dundee, Dundee, UK.
| | | | - Kenny Wood
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, UK
| | - C Tom A Brown
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, UK
| | - Sally Ibbotson
- Photobiology Unit, NHS Tayside, Ninewells Hospital, Dundee, UK; The Scottish Photodynamic Therapy Centre, Dundee, UK; School of Medicine, University of Dundee, Dundee, UK
| | - Ewan Eadie
- Photobiology Unit, NHS Tayside, Ninewells Hospital, Dundee, UK; The Scottish Photodynamic Therapy Centre, Dundee, UK
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Morris J, Stevenson NK, Bookey HT, Kar AK, Brown CTA, Hopkins JM, Dawson MD, Lagatsky AA. 1.9 µm waveguide laser fabricated by ultrafast laser inscription in Tm:Lu 2O 3 ceramic. Opt Express 2017; 25:14910-14917. [PMID: 28789073 DOI: 10.1364/oe.25.014910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 06/10/2017] [Indexed: 06/07/2023]
Abstract
The ultrafast laser inscription technique has been used to fabricate channel waveguides in Tm3+-doped Lu2O3 ceramic gain medium for the first time to our knowledge. Laser operation has been demonstrated using a monolithic microchip cavity with a continuous-wave Ti:sapphire pump source at 796 nm. The maximum output power achieved from the Tm:Lu2O3 waveguide laser was 81 mW at 1942 nm. A maximum slope efficiency of 9.5% was measured with the laser thresholds observed to be in the range of 50-200 mW of absorbed pump power. Propagation losses for this waveguide structure are calculated to be 0.7 dB⋅cm-1 ± 0.3 dB⋅cm-1 at the lasing wavelength.
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Campbell CL, Brown CTA, Wood K, Salvio AG, Inada NM, Bagnato VS, Moseley H. A quantitative study of in vivo protoporphyrin IX fluorescence build up during occlusive treatment phases. Photodiagnosis Photodyn Ther 2017; 18:204-207. [DOI: 10.1016/j.pdpdt.2017.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 01/02/2017] [Accepted: 02/06/2017] [Indexed: 01/06/2023]
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Anastasiou AD, Strafford S, Posada-Estefan O, Thomson CL, Hussain SA, Edwards TJ, Malinowski M, Hondow N, Metzger NK, Brown CTA, Routledge MN, Brown AP, Duggal MS, Jha A. β-pyrophosphate: A potential biomaterial for dental applications. Mater Sci Eng C Mater Biol Appl 2017; 75:885-894. [PMID: 28415544 DOI: 10.1016/j.msec.2017.02.116] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/09/2016] [Accepted: 02/21/2017] [Indexed: 10/20/2022]
Abstract
Tooth hypersensitivity is a growing problem affecting both the young and ageing population worldwide. Since an effective and permanent solution is not yet available, we propose a new methodology for the restoration of dental enamel using femtosecond lasers and novel calcium phosphate biomaterials. During this procedure the irradiated mineral transforms into a densified layer of acid resistant iron doped β-pyrophosphate, bonded with the surface of eroded enamel. Our aim therefore is to evaluate this densified mineral as a potential replacement material for dental hard tissue. To this end, we have tested the hardness of β-pyrophosphate pellets (sintered at 1000°C) and its mineral precursor (brushite), the wear rate during simulated tooth-brushing trials and the cytocompatibility of these minerals in powder form. It was found that the hardness of the β-pyrophosphate pellets is comparable with that of dental enamel and significantly higher than dentine while, the brushing trials prove that the wear rate of β-pyrophosphate is much slower than that of natural enamel. Finally, cytotoxicity and genotoxicity tests suggest that iron doped β-pyrophosphate is cytocompatible and therefore could be used in dental applications. Taken together and with the previously reported results on laser irradiation of these materials we conclude that iron doped β-pyrophosphate may be a promising material for restoring acid eroded and worn enamel.
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Affiliation(s)
- A D Anastasiou
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK.
| | - S Strafford
- Leeds Dental School, Worsley Building, University of Leeds, Leeds LS2 9JT, UK
| | - O Posada-Estefan
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, LS2 9JT, UK
| | - C L Thomson
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
| | - S A Hussain
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK; Cambridge Graphene Centre, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA, UK
| | - T J Edwards
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
| | - M Malinowski
- Leeds Dental School, Worsley Building, University of Leeds, Leeds LS2 9JT, UK
| | - N Hondow
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - N K Metzger
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
| | - C T A Brown
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
| | - M N Routledge
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, LS2 9JT, UK
| | - A P Brown
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - M S Duggal
- Leeds Dental School, Worsley Building, University of Leeds, Leeds LS2 9JT, UK
| | - A Jha
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
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Campbell CL, Brown CTA, Wood K, Moseley H. Modelling topical photodynamic therapy treatment including the continuous production of Protoporphyrin IX. Phys Med Biol 2016; 61:7507-7521. [DOI: 10.1088/0031-9155/61/21/7507] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Campbell CL, Wood K, Brown CTA, Moseley H. Monte Carlo modelling of photodynamic therapy treatments comparing clustered three dimensional tumour structures with homogeneous tissue structures. Phys Med Biol 2016; 61:4840-54. [PMID: 27273196 DOI: 10.1088/0031-9155/61/13/4840] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We explore the effects of three dimensional (3D) tumour structures on depth dependent fluence rates, photodynamic doses (PDD) and fluorescence images through Monte Carlo radiation transfer modelling of photodynamic therapy. The aim with this work was to compare the commonly used uniform tumour densities with non-uniform densities to determine the importance of including 3D models in theoretical investigations. It was found that fractal 3D models resulted in deeper penetration on average of therapeutic radiation and higher PDD. An increase in effective treatment depth of 1 mm was observed for one of the investigated fractal structures, when comparing to the equivalent smooth model. Wide field fluorescence images were simulated, revealing information about the relationship between tumour structure and the appearance of the fluorescence intensity. Our models indicate that the 3D tumour structure strongly affects the spatial distribution of therapeutic light, the PDD and the wide field appearance of surface fluorescence images.
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Affiliation(s)
- C L Campbell
- School of Physics and Astronomy, University of St Andrews, UK
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Campbell CL, Wood K, Valentine RM, Brown CTA, Moseley H. Erratum: Monte Carlo modelling of daylight activated photodynamic therapy (2015 Phys. Med. Biol. 60 4059). Phys Med Biol 2015. [DOI: 10.1088/0031-9155/60/16/6609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Lessing M, Margolis HS, Brown CTA, Gill P, Marra G. Suppression of amplitude-to-phase noise conversion in balanced optical-microwave phase detectors. Opt Express 2013; 21:27057-27062. [PMID: 24216929 DOI: 10.1364/oe.21.027057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We demonstrate an amplitude-to-phase (AM-PM) conversion coefficient for a balanced optical-microwave phase detector (BOM-PD) of 0.001 rad, corresponding to AM-PM induced phase noise 60 dB below the single-sideband relative intensity noise of the laser. This enables us to generate 8 GHz microwave signals from a commercial Er-fibre comb with a single-sideband residual phase noise of -131 dBc Hz(-1) at 1 Hz offset frequency and -148 dBc Hz(-1) at 1 kHz offset frequency.
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Abstract
Understanding the interactions of non-ionizing radiation with living organisms has been the focus of much research over recent decades. The complex nature of these interactions warrants development of theoretical and experimental studies to gain an insight into predicting and monitoring the success of photodynamic therapy (PDT) protocols. There is a major impetus towards evidence-based recommendations for patient diagnosis, treatment and management. Knowledge of the biophysical aspects of PDT is important for improving dosimetry protocols. Fluorescence in clinical PDT may be used to detect and diagnose pre-malignant and malignant conditions, while photobleaching can monitor changes in fluorescence during treatment. Combining empirical fluorescence photobleaching clinical data with computational modelling enables clinical PDT dosimetry protocols to be investigated with a view to optimising treatment regimes. We will discuss how Monte Carlo radiation transfer (MCRT) modelling has been intercalated in the field of fluorescence detection and PDT. In this paper we highlight important aspects of basic research in PDT by reporting on the current utilisation of fluorescence in clinical PDT from both a clinical and theoretical perspective. Understanding and knowledge of light propagation in biological tissue from these perspectives should have a positive impact on treatment planning.
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Affiliation(s)
- Ronan M Valentine
- Photobiology Unit, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
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Choudhary A, Lagatsky AA, Kannan P, Sibbett W, Brown CTA, Shepherd DP. Diode-pumped femtosecond solid-state waveguide laser with a 4.9 GHz pulse repetition rate. Opt Lett 2012; 37:4416-4418. [PMID: 23114314 DOI: 10.1364/ol.37.004416] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the first demonstration of a passively mode-locked, diode-pumped, monolithic Yb:glass channel waveguide laser that incorporates a semiconductor saturable absorber mirror. Stable and self-starting mode-locking is achieved in a Fabry-Perot cavity configuration producing a pulse repetition rate up to 4.9 GHz. The shortest pulse duration of 740 fs is generated with 30 mW of average output power at a center wavelength of 1058 nm. A maximum output power of 81 mW is produced during mode-locking with corresponding pulse duration of 800 fs.
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Affiliation(s)
- A Choudhary
- Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, UK
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Valentine RM, Wood K, Brown CTA, Ibbotson SH, Moseley H. Monte Carlo simulations for optimal light delivery in photodynamic therapy of non-melanoma skin cancer. Phys Med Biol 2012; 57:6327-45. [DOI: 10.1088/0031-9155/57/20/6327] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Crombie C, Walsh DA, Lu W, Zhang S, Zhang Z, Kennedy K, Calvez S, Sibbett W, Brown CTA. Electrically-controlled rapid femtosecond pulse duration switching and continuous picosecond pulse duration tuning in an ultrafast Cr4+:forsterite laser. Opt Express 2012; 20:18138-18144. [PMID: 23038361 DOI: 10.1364/oe.20.018138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate rapid switching between picosecond and femtosecond operational regimes in a Cr(4+):forsterite laser, using an electrically-contacted GaInNAs SESAM with saturable absorption characteristics controlled via the quantum-confined Stark effect. Additionally, continuous picosecond pulse duration tuning by over a factor 3 is reported.
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Affiliation(s)
- C Crombie
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
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Metzger NK, Olle VF, Wonfor A, Penty RV, White IH, Mazilu M, Brown CTA, Sibbett W. Algorithm-based continuous pulse duration tuning and performance control of a mode-locked laser diode. Opt Express 2012; 20:7022-7034. [PMID: 22453382 DOI: 10.1364/oe.20.007022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A control algorithm is presented that addresses the stability issues inherent to the operation of monolithic mode-locked laser diodes. It enables a continuous pulse duration tuning without any onset of Q-switching instabilities. A demonstration of the algorithm performance is presented for two radically different laser diode geometries and continuous pulse duration tuning between 0.5 ps to 2.2 ps and 1.2 ps to 10.2 ps is achieved. With practical applications in mind, this algorithm also facilitates control over performance parameters such as output power and wavelength during pulse duration tuning. The developed algorithm enables the user to harness the operational flexibility from such a laser with 'push-button' simplicity.
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Affiliation(s)
- N K Metzger
- SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK.
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Savitski VG, Metzger NK, Calvez S, Burns D, Sibbett W, Brown CTA. Optical trapping with "on-demand" two-photon luminescence using Cr:LiSAF laser with optically addressed saturable Bragg reflector. Opt Express 2012; 20:7066-7070. [PMID: 22453387 DOI: 10.1364/oe.20.007066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate a diode-pumped Cr:LiSAF laser with controllable and reliable fast switching between its continuous-wave and mode-locked states of operation using an optically-addressed semiconductor Bragg reflector, permitting dyed microspheres to be continuously trapped and monitored using a standard microscope imaging and on-demand two-photon-excited luminescence techniques.
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Affiliation(s)
- Vasili G Savitski
- Institute of Photonics, University of Strathclyde, 106 Rottenrow, Glasgow G4 0NW, UK.
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Abstract
Some background as well as recent progress in the development of femtosecond lasers are discussed together with a brief outline of a few representative emergent applications in biology and medicine that are underpinned by access to such sources. We also provide a short summary of other contributions in this focus issue.
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Affiliation(s)
- W Sibbett
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, KY16 9SS, UK.
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Lagatsky AA, Koopmann P, Fuhrberg P, Huber G, Brown CTA, Sibbett W. Passively mode locked femtosecond Tm:Sc2O3 laser at 2.1 μm. Opt Lett 2012; 37:437-439. [PMID: 22297378 DOI: 10.1364/ol.37.000437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on the passive mode locking of a Tm3+:Sc2O3 laser at 2.1 μm using a semiconductor saturable absorber mirror based on InGaAsSb quantum wells. Transform-limited 218 fs pulses are generated with an average power of 210 mW. A maximum output power of 325 mW is produced during mode locking with the corresponding pulse duration of 246 fs at a pulse repetition frequency of 124.3 MHz. A Ti:sapphire laser is used as the pump source operating at 796 nm.
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Affiliation(s)
- A A Lagatsky
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, UK.
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Stanton-Humphreys MN, Taylor RDT, McDougall C, Hart ML, Brown CTA, Emptage NJ, Conway SJ. Wavelength-orthogonal photolysis of neurotransmittersin vitro. Chem Commun (Camb) 2012; 48:657-9. [DOI: 10.1039/c1cc15135e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lagatsky AA, Calvez S, Gupta JA, Kisel VE, Kuleshov NV, Brown CTA, Dawson MD, Sibbett W. Broadly tunable femtosecond mode-locking in a Tm:KYW laser near 2 μm. Opt Express 2011; 19:9995-10000. [PMID: 21643257 DOI: 10.1364/oe.19.009995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Efficient mode-locking in a Tm:KY(WO(4))(2) laser is demonstrated by using InGaAsSb quantum-well SESAMs. Self-starting ultrashort pulse generation was realized in the 1979-2074 nm spectral region. Maximum average output power up to 411 mW was produced around 1986 nm with the corresponding pulse duration and repetition rate of 549 fs and 105 MHz respectively. Optimised pulse durations of 386 fs were produced with an average power of 235 mW at 2029 nm.
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Affiliation(s)
- A A Lagatsky
- School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK.
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Fusari F, Thomson RR, Jose G, Bain FM, Lagatsky AA, Psaila ND, Kar AK, Jha A, Sibbett W, Brown CTA. Lasing action at around 1.9 μm from an ultrafast laser inscribed Tm-doped glass waveguide. Opt Lett 2011; 36:1566-1568. [PMID: 21540929 DOI: 10.1364/ol.36.001566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report optical guiding and laser action at around 1.9 μm in a Tm³⁺-doped fluorogermanate glass waveguide fabricated using ultrafast laser inscription. A monolithic laser cavity was constructed by directly butt coupling dielectric mirrors to each facet of the 6.0 mm long Tm³⁺-doped waveguide. When the waveguide was pumped by a Ti:sapphire laser tuned to 791 nm, laser oscillation was achieved at around 1.91 μm. This waveguide laser exhibited a maximum slope efficiency of 6% and a maximum output power of 32 mW when pumped with 620 mW of incident laser power.
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Affiliation(s)
- F Fusari
- Scottish Universities Physics Alliance, J. F. Allen Physics Research Laboratories, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, Scotland, UK
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24
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Valentine RM, Brown CTA, Moseley H, Ibbotson S, Wood K. Monte Carlo modeling of in vivo protoporphyrin IX fluorescence and singlet oxygen production during photodynamic therapy for patients presenting with superficial basal cell carcinomas. J Biomed Opt 2011; 16:048002. [PMID: 21529097 DOI: 10.1117/1.3562540] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present protoporphyrin IX (PpIX) fluorescence measurements acquired from patients presenting with superficial basal cell carcinoma during photodynamic therapy (PDT) treatment, facilitating in vivo photobleaching to be monitored. Monte Carlo (MC) simulations, taking into account photobleaching, are performed on a three-dimensional cube grid, which represents the treatment geometry. Consequently, it is possible to determine the spatial and temporal changes to the origin of collected fluorescence and generated singlet oxygen. From our clinical results, an in vivo photobleaching dose constant, β of 5-aminolaevulinic acid-induced PpIX fluorescence is found to be 14 ± 1 J/cm(2). Results from our MC simulations suggest that an increase from our typical administered treatment light dose of 75-150 J/cm(2) could increase the effective PDT treatment initially achieved at a depth of 2.7-3.3 mm in the tumor, respectively. Moreover, this increase reduces the surface PpIX fluorescence from 0.00012 to 0.000003 of the maximum value recorded before treatment. The recommendation of administrating a larger light dose, which advocates an increase in the treatment time after surface PpIX fluorescence has diminished, remains valid for different sets of optical properties and therefore should have a beneficial outcome on the total treatment effect.
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Affiliation(s)
- Ronan M Valentine
- University of St. Andrews, School of Physics and Astronomy, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
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25
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Valentine RM, Ibbotson SH, Brown CTA, Wood K, Moseley H. A Quantitative Comparison of 5-Aminolaevulinic Acid- and Methyl Aminolevulinate-Induced Fluorescence, Photobleaching and Pain During Photodynamic Therapy. Photochem Photobiol 2010; 87:242-9. [DOI: 10.1111/j.1751-1097.2010.00829.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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26
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Fusari F, Lagatsky AA, Jose G, Calvez S, Jha A, Dawson MD, Gupta JA, Sibbett W, Brown CTA. Femtosecond mode-locked Tm(3+) and Tm(3+)-Ho(3+) doped 2 μm glass lasers. Opt Express 2010; 18:22090-22098. [PMID: 20941110 DOI: 10.1364/oe.18.022090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report on the spectroscopic characterization, continuous-wave and continuous wave mode-locked laser performance of bulk Tm(3+):GPNG fluorogermanate and Tm(3+)-Ho(3+):TZN tellurite glass lasers around 2 μm. A slope efficiency of up to 50% and 190 mW of output power were achieved from the Tm(3+):GPNG laser at 1944 nm during continuous wave operation. The Tm(3+)-Ho(3+):TZN laser produced a 26% slope efficiency with a maximum output power of 74 mW at 2012 nm. The Tm(3+):GPNG produced near-transform-limited pulses of 410 fs duration centered at 1997 nm with up to 84 mW of average output power and repetition frequency of 222 MHz when was passively modelocked using an ion-implanted InGaAsSb-based quantum well SESAM. Using the same SESAM, the Tm(3+)-Ho(3+):TZN laser generated 630-fs pulses with 38 mW of average output power at 2012 nm. Data analysis of pulses at different intracavity pulse energies provided an estimation of n(2) at 2012 nm of 2.9 × 10(-15) cm(2)/W for the Tm(3+)-Ho(3+):TZN.
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Affiliation(s)
- F Fusari
- Scottish Universities Physics Alliance, J. F. Allen School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, Scotland, UK.
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27
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Brown CTA, Deckert V, Sergeev AM, Zheltikov AM. Nanobiophotonics: photons that shine their light on the life at the nanoscale. J Biophotonics 2010; 3:639-640. [PMID: 20860049 DOI: 10.1002/jbio.201000521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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28
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Lagatsky AA, Han X, Serrano MD, Cascales C, Zaldo C, Calvez S, Dawson MD, Gupta JA, Brown CTA, Sibbett W. Femtosecond (191 fs) NaY(WO4)2 Tm,Ho-codoped laser at 2060 nm. Opt Lett 2010; 35:3027-3029. [PMID: 20847767 DOI: 10.1364/ol.35.003027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report, for the first time to our knowledge, femtosecond-pulse operation of a Tm,Ho:NaY(WO(4))(2) laser at around 2060 nm. Transform-limited 191 fs pulses are produced with an average output power of 82 mW at a 144 MHz pulse repetition frequency. Maximum output power of up to 155 mW is generated with a corresponding pulse duration of 258 fs. An ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror is used for passive mode-locking maintenance.
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Affiliation(s)
- A A Lagatsky
- School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK.
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29
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Metzger NK, Lubeigt W, Burns D, Griffith M, Laycock L, Lagatsky AA, Brown CTA, Sibbett W. Ultrashort-pulse laser with an intracavity phase shaping element. Opt Express 2010; 18:8123-8134. [PMID: 20588657 DOI: 10.1364/oe.18.008123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A novel ultrashort-pulse laser cavity configuration that incorporates an intracavity deformable mirror as a phase control element is reported. A user-defined spectral phase relation of 0.7 radians relative shift could be produced at around 1035 nm. Phase shaping as well as pulse duration optimization was achieved via a computer-controlled feedback loop.
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Affiliation(s)
- N K Metzger
- SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK.
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30
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Han X, Fusari F, Serrano MD, Lagatsky AA, Cano-Torres JM, Brown CTA, Zaldo C, Sibbett W. Continuous-wave laser operation of Tm and Hoco-doped NaY(WO(4))(2) and NaLu(WO(4))(2) crystals. Opt Express 2010; 18:5413-5419. [PMID: 20389557 DOI: 10.1364/oe.18.005413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Tetragonal single crystals of NaT(WO(4))(2) (T = Y or Lu) co-doped with Tm(3+) and Ho(3+) ions have been employed for broadly tunable and efficient room-temperature laser operation at around 2 mum. With Ti:sapphire laser pumping at 795 nm, a slope efficiency and a maximum output power as high as 48% and 265 mW, respectively, have been achieved at 2050 nm from a Tm,Ho:NaY(WO(4))(2) crystal. Tuning from 1830 nm to 2080 nm has also been obtained using an intracavity Lyot filter.
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Affiliation(s)
- X Han
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, c/ Sor Juana Inés de la Cruz 3. 28049 Madrid, Spain
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31
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Lagatsky AA, Fusari F, Calvez S, Kurilchik SV, Kisel VE, Kuleshov NV, Dawson MD, Brown CTA, Sibbett W. Femtosecond pulse operation of a Tm,Ho-codoped crystalline laser near 2 microm. Opt Lett 2010; 35:172-174. [PMID: 20081958 DOI: 10.1364/ol.35.000172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate, for the first time to our knowledge, femtosecond-regime mode locking of a Tm,Ho-codoped crystalline laser operating in the 2 microm spectral region. Transform-limited 570 fs pulses were generated at 2055 nm by a Tm,Ho:KY(WO(4))(2) laser that produced an average output power of 130 mW at a pulse repetition frequency of 118 MHz. Mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror.
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Affiliation(s)
- A A Lagatsky
- School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, UK.
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32
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Bain FM, Lagatsky AA, Thomson RR, Psaila ND, Kuleshov NV, Kar AK, Sibbett W, Brown CTA. Ultrafast laser inscribed Yb:KGd(WO4)2 and Yb:KY(WO4)2 channel waveguide lasers. Opt Express 2009; 17:22417-22422. [PMID: 20052165 DOI: 10.1364/oe.17.022417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate laser action in diode-pumped microchip monolithic cavity channel waveguides of Yb:KGd(WO(4))(2) and Yb:KY(WO(4))(2) that were fabricated by ultrafast laser writing. The maximum output power achieved was 18.6 mW with a threshold of approximately 100 mW from an Yb:KGd(WO(4))(2) waveguide laser operating at 1023 nm. The propagation losses for this waveguide structure were measured to be 1.9 dBcm(-1).
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Affiliation(s)
- F M Bain
- J. F. Allen Physics Research Laboratories, School of Physics and Astronomy, St Andrews, Fife, Scotland KY16 9SS, UK.
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33
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Lagatsky AA, Fusari F, Calvez S, Gupta JA, Kisel VE, Kuleshov NV, Brown CTA, Dawson MD, Sibbett W. Passive mode locking of a Tm,Ho:KY(WO4)2 laser around 2 microm. Opt Lett 2009; 34:2587-2589. [PMID: 19724498 DOI: 10.1364/ol.34.002587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the first demonstration, to our knowledge, of passive mode locking in a Tm(3+), Ho(3+)-codoped KY(WO(4))(2) laser operating in the 2000-2060 nm spectral region. An InGaAsSb-based quantum well semiconductor saturable absorber mirror is used for the initiation and stabilization of the ultrashort pulse generation. Pulses as short as 3.3 ps were generated at 2057 nm with average output powers up to 315 mW at a pulse repetition frequency of 132 MHz for 1.15 W of absorbed pump power at 802 nm from a Ti:sapphire laser.
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Affiliation(s)
- A A Lagatsky
- School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK.
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34
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Tan KM, Mazilu M, Chow TH, Lee WM, Taguichi K, Ng BK, Sibbett W, Herrington CS, Brown CTA, Dholakia K. In-fiber common-path optical coherence tomography using a conical-tip fiber. Opt Express 2009; 17:2375-84. [PMID: 19219141 DOI: 10.1364/oe.17.002375] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Common-path optical coherence tomography (CPOCT) is known to reduce group velocity dispersion and polarization mismatch between the reference and the sample arm as both arms share the same physical path. Existing implementations of CPOCT typically require one to incorporate an additional cover glass within the beam path of the sample arm to provide a reference signal. In this paper, we aim to further reduce this step by directly making use of the back-reflected signal, arising from a conical lens-tip fiber, as a reference signal. The conical lens, which is directly manufactured onto the optical fiber tip via a simple selective-chemical etching process, fulfils two functions acting as both the imaging lens and the self-aligning reference plane. We use a Fourier-domain OCT system to demonstrate the feasibility of this technique upon biological tissue. An in-fiber CPOCT technique may prove potentially useful in endoscopic OCT imaging.
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Affiliation(s)
- K M Tan
- SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9SS, UK.
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35
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Bain FM, Lagatsky AA, Kurilchick SV, Kisel VE, Guretsky SA, Luginets AM, Kalanda NA, Kolesova IM, Kuleshov NV, Sibbett W, Brown CTA. Continuous-wave and Q-switched operation of a compact, diode-pumped Yb3+:KY(WO4)2 planar waveguide laser. Opt Express 2009; 17:1666-1670. [PMID: 19188997 DOI: 10.1364/oe.17.001666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A diode-pumped LPE-grown Yb:KYW planar waveguide laser is demonstrated in a microchip monolithic cavity configuration. Output powers as high as 148 mW and thresholds as low as 40 mW were demonstrated during continuous-wave operation. Pulses of 170 ns duration with maximum pulse energy of 44 nJ at a 722 kHz repetition rate were generated when Q-switched using a semiconductor saturable absorber mirror.
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Affiliation(s)
- F M Bain
- J. F. Allen Physics Research Laboratories, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife, Scotland, UK
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36
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Van Ryssen MP, Avlonitis N, Giniatullin R, McDougall C, Carr JL, Stanton-Humphreys MN, Borgström ELA, Brown CTA, Fayuk D, Surin A, Niittykoski M, Khiroug L, Conway SJ. Synthesis, photolysis studies and in vitro photorelease of caged TRPV1 agonists and antagonists. Org Biomol Chem 2009; 7:4695-707. [DOI: 10.1039/b914981c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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37
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Avlonitis N, Chalmers S, McDougall C, Stanton-Humphreys MN, Brown CTA, McCarron JG, Conway SJ. Caged AG10: new tools for spatially predefined mitochondrial uncoupling. Mol BioSyst 2009; 5:450-7. [DOI: 10.1039/b820415m] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Fusari F, Lagatsky AA, Richards B, Jha A, Sibbett W, Brown CTA. Spectroscopic and lasing performance of Tm3+-doped bulk TZN and TZNG tellurite glasses operating around 1.9 microm. Opt Express 2008; 16:19146-19151. [PMID: 19582007 DOI: 10.1364/oe.16.019146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report spectroscopic and bulk laser performance characteristics for Tm(3+)-doped tellurite glasses when used as gain media operating around 1.9 microm. Two glass hosts studied are TZN and TZNG and their performances have been compared. In each case, well-characterized cw laser performance was obtained and this has been related to detailed spectroscopic measurements of the important lasing parameters of the laser transitions around 1900 nm when pumped at 793 nm. The maximum output power achieved was 124 mW from the TZNG sample with an associated slope efficiency of 28 % with a tuning range of 135 nm. Efficiency and loss analyses yielded a calculated maximum attainable efficiency of 48 % in Tm(3+):TZN compared to 28 % for the TZNG host.
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Affiliation(s)
- F Fusari
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, St Andrews, Scotland, UK.
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39
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Metzger NK, Leburn CG, Lagatsky AA, Brown CTA, Calvez S, Burns D, Sun HD, Dawson MD, Le Dû M, Harmand JC, Sibbett W. Femtosecond pulse generation around 1500 nm using a GaInNAsSb SESAM. Opt Express 2008; 16:18739-18744. [PMID: 19581960 DOI: 10.1364/oe.16.018739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The operation of a femtosecond Cr(4+):YAG laser that incorporates a novel GaInNAsSb semiconductor saturable Bragg reflector is reported. In the mode-locked regime 230 fs pulses centred at 1528 nm were generated at an average output power of 280 mW. The SESAM exhibited a low saturation fluence of 10 microJ/cm(2) and a short recovery time of 12 ps.
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Affiliation(s)
- N K Metzger
- SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, UK.
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40
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Lagatsky AA, Brown CTA, Sibbett W, Holmgren SJ, Canalias C, Pasiskevicius V, Laurell F, Rafailov EU. Efficient doubling of femtosecond pulses in aperiodically and periodically poled KTP crystals. Opt Express 2007; 15:1155-1160. [PMID: 19532343 DOI: 10.1364/oe.15.001155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Efficient doubling of femtosecond pulses in periodically and aperiodically poled KTP crystals is demonstrated by employing the quasiphasematched frequency conversion technique. Conversion efficiencies as high as 60% were achieved using either aperiodically or periodically poled KTP nonlinear crystals in an extracavity, single-pass configuration using a diode-pumped femtosecond Yb:KYW laser as the pump source. The temporal characteristics of the frequency-doubled pulses as a function of focusing conditions in a "thick" nonlinear crystal regime have been investigated experimentally and pulses as short as 177 fs have been generated at around 520 nm under strong focusing conditions using a KTP crystal with aperiodic poling.
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41
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Stevenson D, Agate B, Tsampoula X, Fischer P, Brown CTA, Sibbett W, Riches A, Gunn-Moore F, Dholakia K. Femtosecond optical transfection of cells: viability and efficiency. Opt Express 2006; 14:7125-33. [PMID: 19529083 DOI: 10.1364/oe.14.007125] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Photoporation is a rapidly expanding technique for the introduction of macromolecules into single cells. However, there remains no study into the true efficiency of this procedure. Here, we present a detailed analysis of transfection efficiency and cell viability for femtosecond optical transfection using a titanium sapphire laser at 800 nm. Photoporation of 4000 Chinese Hamster ovary cells was performed, representing the largest optical transfection study reported to date. We have investigated a range of laser fluences at the cell membrane and, at 1.2 microJ/cm(2), have found an average transfection efficiency of 50 +/- 10%. Contrary to recent literature, in which 100% efficiency is claimed, our measure of efficiency accounts for all irradiated cells, including those lost as a result of laser treatment, thereby providing a true biological measure of the technique.
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Affiliation(s)
- D Stevenson
- Interdisciplinary Centre for Medical Photonics, School of Physics & Astronomy, University of St Andrews, St Andrews, KY16 9SS, Scotland, UK.
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42
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Fischer P, Carruthers AE, Volke-Sepulveda K, Wright EM, Brown CTA, Sibbett W, Dholakia K. Enhanced optical guiding of colloidal particles using a supercontinuum light source. Opt Express 2006; 14:5792-5802. [PMID: 19516748 DOI: 10.1364/oe.14.005792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate enhanced optical guiding distances for microscopic particles using a supercontinuum light beam. The enhanced spectral bandwidth of the source leads to an elongated focal region. As a result we obtain a significant radial gradient force and axial radiation pressure force over a longer distance when compared to a monochromatic Gaussian beam. The guiding distances of up to 3mm that are observed for micron-sized particles with the supercontinuum beam are approximately twice those observed using continuous wave and femtosecond laser sources when considering beams of equivalent diameter. This guiding scheme is expected to be applicable to colloidal particles, biological cells and cold atom ensembles.
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43
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McWilliam A, Lagatsky AA, Brown CTA, Sibbett W, Zhukov AE, Ustinov VM, Vasil'ev AP, Rafailov EU. Quantum-dot-based saturable absorber for femtosecond mode-locked operation of a solid-state laser. Opt Lett 2006; 31:1444-6. [PMID: 16642133 DOI: 10.1364/ol.31.001444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A quantum-dot-based saturable absorber has been demonstrated to initiate the generation of femtosecond pulses from a passively mode-locked solid-state laser. Control and tuning of the pulse duration from 58 ps to 158 fs was achieved. The 158 fs transform-limited pulses at 1280 nm are the shortest pulses that were produced from the Cr:forsterite laser passively mode locked by an InAs/InGaAs quantum-dot semiconductor saturable absorber mirror.
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Affiliation(s)
- A McWilliam
- J.F. Allen Physics Research Laboratories, School of Physics and Astronomy, University of St Andrews, UK
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44
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Fischer P, Little H, Smith RL, Lopez-Mariscal C, Brown CTA, Sibbett W, Dholakia K. Wavelength dependent propagation and reconstruction of white light Bessel beams. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1464-4258/8/5/018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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45
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Lagatsky AA, Sarmani AR, Brown CTA, Sibbett W, Kisel VE, Selivanov AG, Denisov IA, Troshin AE, Yumashev KV, Kuleshov NV, Matrosov VN, Matrosova TA, Kupchenko MI. Yb3+-doped YVO4 crystal for efficient Kerr-lens mode locking in solid-state lasers. Opt Lett 2005; 30:3234-6. [PMID: 16342731 DOI: 10.1364/ol.30.003234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report the first demonstration, to our knowledge, of soft-aperture Kerr-lens mode locking in a diode-pumped femtosecond Yb3+:YVO4 laser. Near-transform-limited pulses as short as 61 fs are generated around a center wavelength of 1050 nm with an output power of 54 mW and a pulse repetition frequency of 104.5 MHz. This is, to our knowledge, the shortest pulse generated directly from an Yb laser having a crystalline host material. The femtosecond operation has a mode-locking threshold at an absorbed pump power of 190 mW. The nonlinear refractive indexes of the Yb3+:YVO4 crystal have been measured to be 19 x 10(-16) cm2/W and 15 x 10(-16) cm2/W for the sigma and pi polarizations, respectively, at 1080 nm.
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Affiliation(s)
- A A Lagatsky
- J F Allen Physics Research Laboratories, School of Physics and Astronomy, University of St Andrews, Scotland, UK.
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Carr JL, Wease KN, Van Ryssen MP, Paterson S, Agate B, Gallagher KA, Brown CTA, Scott RH, Conway SJ. In vitro photo-release of a TRPV1 agonist. Bioorg Med Chem Lett 2005; 16:208-12. [PMID: 16213723 DOI: 10.1016/j.bmcl.2005.09.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 09/06/2005] [Indexed: 11/20/2022]
Abstract
Intracellular photolysis of a novel 'caged' capsaicin analogue results in in vitro activation of the capsaicin receptor TRPV1.
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Affiliation(s)
- James L Carr
- EaStCHEM, School of Chemistry and Centre for Biomolecular Sciences, University of St. Andrews, St. Andrews, Fife KY16 9ST, UK
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Lagatsky AA, Rafailov EU, Sarmani AR, Brown CTA, Sibbett W, Ming L, Smith PGR. Efficient femtosecond green-light source with a diode-pumped mode-locked Yb3+:KY(WO4)2 laser. Opt Lett 2005; 30:1144-6. [PMID: 15943294 DOI: 10.1364/ol.30.001144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Efficient generation of femtosecond pulses at 524 nm is demonstrated by the extracavity frequency doubling of the output of a diode-pumped femtosecond Yb3+:KY(WO4)2 laser using a periodically poled LiTaO3 crystal. An average second-harmonic power of 120 mW is produced at an internal conversion efficiency of 40%. The temporal characteristics of the frequency-doubled pulses as a function of focusing conditions in a thick nonlinear crystal are investigated experimentally, and pulses as short as 225 fs are generated at a pulse repetition frequency of 86 MHz.
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Affiliation(s)
- A A Lagatsky
- The Ultrafast Photonics Collaboration, J. F. Allen Physics Research Laboratories, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, Scotland, UK.
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