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Wang J, Song Y, Song X, Zhang W, Yang J, Xuan Z. Integrated Optical Waveguide Electric Field Sensors Based on Bismuth Germanate. SENSORS (BASEL, SWITZERLAND) 2024; 24:5570. [PMID: 39275480 PMCID: PMC11397851 DOI: 10.3390/s24175570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2024] [Revised: 08/13/2024] [Accepted: 08/20/2024] [Indexed: 09/16/2024]
Abstract
Bismuth germanate (Bi4Ge3O12, BGO) is a widely used optical sensing material with a high electro-optic coefficient, ideal for optical electric field sensors. Achieving high precision in electric field sensing requires fabricating optical waveguides on BGO. Traditional waveguide writing methods face challenges with this material. This study explores using femtosecond laser writing technology for preparing waveguides on BGO, leveraging ultrafast optical fields for superior material modification. Our experimental analysis shows that a cladding-type waveguide, written with a femtosecond laser at 200 kHz repetition frequency and 10.15 mW average power (pulse energy of 50.8 nJ), exhibits excellent light-guiding characteristics. Simulations of near-field optical intensity distribution and refractive index variations using the refractive index reconstruction method demonstrate that the refractive index modulation ensures single-mode transmission and effectively confines light to the core layer. In situ refractive index characterization confirms the feasibility of fabricating a waveguide with a refractive index reduction on BGO. The resulting waveguide has a loss per unit length of approximately 1.2 dB/cm, marking a successful fabrication. Additionally, we design an antenna electrode, analyze sensor performance indicators, and integrate a preparation process plan for the antenna electrode. This achievement establishes a solid experimental foundation for future studies on BGO crystal waveguides in electric field measurement applications.
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Affiliation(s)
- Jin Wang
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
| | - Yilin Song
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
| | - Xuefei Song
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
| | - Wei Zhang
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
| | - Junqi Yang
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
| | - Zhi Xuan
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
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Croitoru G, Jipa F, Greculeasa M, Broasca A, Voicu F, Gheorghe L, Pavel N. Buried Depressed-Cladding Waveguides Inscribed in Nd 3+ and Yb 3+ Doped CLNGG Laser Crystals by Picosecond-Laser Beam Writing. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1758. [PMID: 38673115 PMCID: PMC11051540 DOI: 10.3390/ma17081758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/26/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024]
Abstract
Buried depressed-cladding waveguides were fabricated in 0.7-at.% Nd:Ca3Li0.275Nb1.775Ga2.95O12 (Nd:CLNGG) and 7.28-at.% Yb:CLNGG disordered laser crystals grown by Czochralski method. Circular waveguides with 100 μm diameters were inscribed in both crystals with picosecond (ps) laser pulses at 532 nm of 0.15 μJ energy at 500 kHz repetition rate. A line-by-line writing technique at 1 mm/s scanning speed was used. Laser emission at 1.06 μm (with 0.35 mJ pulse energy) and at 1.03 μm (with 0.16 mJ pulse energy) was obtained from the waveguide inscribed in Nd:CLNGG and Yb:CLNGG, respectively, employing quasi-continuous wave pumping with fiber-coupled diode lasers. The waveguide realized in RE3+-doped CLNGG crystals using ps-laser pulses at high repetition rates could provide Q-switched or mode-locked miniaturized lasers for a large number of photonic applications.
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Affiliation(s)
- Gabriela Croitoru
- Laboratory of Solid-State Quantum Electronics, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (M.G.); (A.B.); (F.V.); (L.G.); (N.P.)
| | - Florin Jipa
- Photonic Investigations Laboratory—PhIL, Center for Advanced Laser Technology, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania;
| | - Madalin Greculeasa
- Laboratory of Solid-State Quantum Electronics, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (M.G.); (A.B.); (F.V.); (L.G.); (N.P.)
| | - Alin Broasca
- Laboratory of Solid-State Quantum Electronics, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (M.G.); (A.B.); (F.V.); (L.G.); (N.P.)
| | - Flavius Voicu
- Laboratory of Solid-State Quantum Electronics, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (M.G.); (A.B.); (F.V.); (L.G.); (N.P.)
| | - Lucian Gheorghe
- Laboratory of Solid-State Quantum Electronics, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (M.G.); (A.B.); (F.V.); (L.G.); (N.P.)
| | - Nicolaie Pavel
- Laboratory of Solid-State Quantum Electronics, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania; (M.G.); (A.B.); (F.V.); (L.G.); (N.P.)
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Gebremichael W, Oliwa D, Fernandes J, Dorrer C, Qiao J. Ultrafast-laser-inscribed multiscan type-I mid-infrared waveguides and beamsplitters in IG2. OPTICS EXPRESS 2024; 32:8042-8058. [PMID: 38439471 DOI: 10.1364/oe.515347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/05/2024] [Indexed: 03/06/2024]
Abstract
This study reports the fabrication and characterization of various configurations of mid-infrared waveguides and beamsplitters within the chalcogenide glass IG2 using ultrafast laser inscription (ULI). Our investigation reveals two distinct regimes of ULI modification: weak and strong. The strong regime, marked by higher pulse energies, presents darker and prominent waveguide morphology, enabling efficient light guiding at 4.55 µm, but with higher scattering losses at shorter wavelengths. In the weak regime, we observed a significant enhancement in the mode confinement and a reduction in the propagation loss within the multilayer structures. We have investigated key geometric and inscription parameters such as inscription pulse energy and number of layers, as well as arm separation and splitting angles for beamsplitters. We have successfully fabricated beamsplitters with configurations ranging from 1 × 2 to 1 × 8, achieving a uniform splitting ratio over 96% and a splitting loss as low as 0.4 dB at 4.55 µm. These findings highlight the significant potential of ULI-based IG2 waveguides and beamsplitters for mid-infrared photonics.
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Dupont A, Lapointe J, Pouliot S, Vallée R. From near-UV to long-wave infrared waveguides inscribed in barium fluoride using a femtosecond laser. OPTICS LETTERS 2021; 46:3925-3928. [PMID: 34388776 DOI: 10.1364/ol.430322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Depressed-cladding waveguides (DCWs) of various sizes were inscribed in barium fluoride, allowing single-mode operation in the entirety of its transmission window (λ=0.2-12µm). Using femtosecond laser pulses at 515 nm, type I laser modified tracks were overlapped to form circular waveguides, whose cross-sectional geometry and numerical aperture were tailored to accommodate 0.405, 2.85, and 10.6 µm light. The mode profile, propagation loss, refractive index profile, and numerical aperture of the optimized waveguides were analyzed and compared with theory. We particularly demonstrate the challenging inscription of a large DCW for single-mode operation at 10.6 µm with propagation loss of <0.63dB/cm.
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Record-high positive refractive index change in bismuth germanate crystals through ultrafast laser enhanced polarizability. Sci Rep 2020; 10:15142. [PMID: 32934325 PMCID: PMC7492192 DOI: 10.1038/s41598-020-72234-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/06/2020] [Indexed: 11/08/2022] Open
Abstract
Unlike other crystals, the counter intuitive response of bismuth germanate crystals ([Formula: see text], BGO) to form localized high refractive index contrast waveguides upon ultrafast laser irradiation is explained for the first time. While the waveguide formation is a result of a stoichiometric reorganization of germanium and oxygen, the origin of positive index stems from the formation of highly polarisable non-bridging oxygen complexes. Micro-reflectivity measurements revealed a record-high positive refractive index contrast of [Formula: see text]. The currently accepted view that index changes [Formula: see text] could be brought about only by engaging heavy metal elements is strongly challenged by this report. The combination of a nearly perfect step-index profile, record-high refractive index contrast, easily tunable waveguide dimensions, and the intrinsic high optical non-linearity, electro-optic activity and optical transparency up to [Formula: see text] of BGO make these waveguides a highly attractive platform for compact 3D integrated optics.
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Kuz’micheva G, Kaurova I. Peculiar Structural Effects in Pure and Doped Functional Single Crystals of Complex Compositions. Molecules 2020; 25:molecules25102451. [PMID: 32466174 PMCID: PMC7287726 DOI: 10.3390/molecules25102451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 11/16/2022] Open
Abstract
Results of a detailed structural characterization of nominally pure and doped single crystals of scheelite, eulytin, and perovskite families obtained by melt methods were considered and analyzed. The influence of growth and post-growth annealing conditions on actual compositions of crystals is shown. The reasons for the coloration of the crystals are explained. A change in crystal symmetry due to crystal–chemical and growth reasons is considered. The use of structural analysis and X-ray absorption spectroscopy is substantiated to reveal the role of activator ions in the formation of statistical and local structures, respectively. A relationship between the distribution of activator ions over crystallographic sites and photoluminescent parameters of materials is established, which allows selecting optimal systems for the application. The combined results of studying single-crystal compounds of other classes (huntite, sillenite, whitlockite, garnet, tetragonal bronzes) allow formulating and summarizing structural effects that appeared in the systems and caused by various factors and, in many cases, due to the local environment of cations. A principal difference in the structural behavior of solid solutions and doped compounds is shown. The methodology developed for single-crystal samples of complex compositions can be recommended for the systematic structural studies of functional materials of different compositions.
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Skryabin N, Kalinkin A, Dyakonov I, Kulik S. Femtosecond Laser Written Depressed-Cladding Waveguide 2 × 2, 1 × 2 and 3 × 3 Directional Couplers in Tm 3+:YAG Crystal. MICROMACHINES 2019; 11:mi11010001. [PMID: 31861295 PMCID: PMC7019769 DOI: 10.3390/mi11010001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 11/16/2022]
Abstract
Ion-doped crystal-based compact devices capable of beam splitting and coupling are enthralling for a broad range of classical and quantum integrated photonics applications. In this work, we report on the fabrication of depressed-cladding waveguide 2D 2 × 2, 1 × 2 and 3D 3 × 3 directional couplers in Tm3+:YAG crystal by femtosecond laser writing. The performances of the couplers are characterized at 810 nm, showing single-mode guidance, polarization independence, finely matched splitting ratios. These results open up new opportunities in the beneficial fabrication of 3D circuits and devices in crystals.
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Affiliation(s)
- Nikolay Skryabin
- Quantum Technologies Center and Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1, building 35, Moscow 119991, Russia; (N.S.); (A.K.); (S.K.)
- Moscow Institute Physics and Technology, Institutskiy per. 9, Dolgoprudny 141701, Russia
| | - Alexander Kalinkin
- Quantum Technologies Center and Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1, building 35, Moscow 119991, Russia; (N.S.); (A.K.); (S.K.)
| | - Ivan Dyakonov
- Quantum Technologies Center and Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1, building 35, Moscow 119991, Russia; (N.S.); (A.K.); (S.K.)
- Correspondence:
| | - Sergei Kulik
- Quantum Technologies Center and Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1, building 35, Moscow 119991, Russia; (N.S.); (A.K.); (S.K.)
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Bérubé JP, Lapointe J, Dupont A, Bernier M, Vallée R. Femtosecond laser inscription of depressed cladding single-mode mid-infrared waveguides in sapphire. OPTICS LETTERS 2019; 44:37-40. [PMID: 30645539 DOI: 10.1364/ol.44.000037] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 11/24/2018] [Indexed: 05/27/2023]
Abstract
Mid-infrared optical waveguides were inscribed in sapphire with femtosecond pulses at 515 nm. We show that such pulses induce a smooth negative refractive index change allowing for the inscription of a depressed cladding waveguide by closely overlapping the corresponding type I modification traces. The resulting structure consists of a highly symmetrical, uniform, and homogeneous waveguide. The size and numerical aperture of the waveguides were tailored to achieve efficient transmission in the mid-infrared. Single mode operation at a wavelength of 2850 nm and propagation loss of <0.37 dB/cm are reported for a 33 mm long depressed cladding waveguide. Thermal annealing was performed, and the refractive index contrast was still preserved to 50% (i.e., Δn=∼2.5×10-3) up to 1400°C.
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Li L, Nie W, Li Z, Romero C, Rodriguez-Beltrán RI, Vázquez de Aldana JR, Chen F. Laser-writing of ring-shaped waveguides in BGO crystal for telecommunication band. OPTICS EXPRESS 2017; 25:24236-24241. [PMID: 29041368 DOI: 10.1364/oe.25.024236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/18/2017] [Indexed: 06/07/2023]
Abstract
We report on the fabrication of ring-shaped waveguides operating at the telecommunication band in a cubic Bi4Ge3O12 (BGO) crystal by using technique of femtosecond laser writing. In the regions of laser written tracks in BGO crystal, positive refractive index is induced, resulting in so-called Type I configuration. The modal profiles are within the designed track cladding with ring-shaped geometries, which are analogous to circular optical lattices. The homogenous guidance along both TE and TM polarizations has been obtained at telecommunication wavelength of 1.55 μm. Both straight and S-curved waveguiding structures have been produced with ring-shaped configurations. This work paves the way to fabricate complex photonic networks for telecommunications by using ring-shaped waveguides in compact chips.
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Li L, Nie W, Li Z, Lu Q, Romero C, Vázquez de Aldana JR, Chen F. All-laser-micromachining of ridge waveguides in LiNbO 3 crystal for mid-infrared band applications. Sci Rep 2017; 7:7034. [PMID: 28765573 PMCID: PMC5539162 DOI: 10.1038/s41598-017-07587-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 06/20/2017] [Indexed: 11/09/2022] Open
Abstract
The femtosecond laser micromachining of transparent optical materials offers a powerful and feasible solution to fabricate versatile photonic components towards diverse applications. In this work, we report on a new design and fabrication of ridge waveguides in LiNbO3 crystal operating at the mid-infrared (MIR) band by all-femtosecond-laser microfabrication. The ridges consist of laser-ablated sidewalls and laser-written bottom low-index cladding tracks, which are constructed for horizontal and longitudinal light confinement, respectively. The ridge waveguides are found to support good guidance at wavelength of 4 μm. By applying this configuration, Y-branch waveguiding structures (1 × 2 beam splitters) have been produced, which reach splitting ratios of ∼1:1 at 4 μm. This work paves a simple and feasible way to construct novel ridge waveguide devices in dielectrics through all-femtosecond-laser micro-processing.
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Affiliation(s)
- Lingqi Li
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China
| | - Weijie Nie
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China
| | - Ziqi Li
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China
| | - Qingming Lu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China
| | - Carolina Romero
- Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada, University of Salamanca, Salamanca, 37008, Spain
| | - Javier R Vázquez de Aldana
- Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada, University of Salamanca, Salamanca, 37008, Spain
| | - Feng Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
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Nie W, Jia Y, Vázquez de Aldana JR, Chen F. Efficient Second Harmonic Generation in 3D Nonlinear Optical-Lattice-Like Cladding Waveguide Splitters by Femtosecond Laser Inscription. Sci Rep 2016; 6:22310. [PMID: 26924255 PMCID: PMC4770408 DOI: 10.1038/srep22310] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 02/09/2016] [Indexed: 11/09/2022] Open
Abstract
Integrated photonic devices with beam splitting function are intriguing for a broad range of photonic applications. Through optical-lattice-like cladding waveguide structures fabricated by direct femtosecond laser writing, the light propagation can be engineered via the track-confined refractive index profiles, achieving tailored output beam distributions. In this work, we report on the fabrication of 3D laser-written optical-lattice-like structures in a nonlinear KTP crystal to implement 1 × 4 beam splitting. Second harmonic generation (SHG) of green light through these nonlinear waveguide beam splitter structures provides the capability for the compact visible laser emitting devices. With Type II phase matching of the fundamental wavelength (@ 1064 nm) to second harmonic waves (@ 532 nm), the frequency doubling has been achieved through this three-dimensional beam splitter. Under 1064-nm continuous-wave fundamental-wavelength pump beam, guided-wave SHG at 532 nm are measured with the maximum power of 0.65 mW and 0.48 mW for waveguide splitters (0.67 mW and 0.51 mW for corresponding straight channel waveguides), corresponding to a SH conversion efficiency of approximately ~14.3%/W and 13.9%/W (11.2%/W, 11.3%/W for corresponding straight channel waveguides), respectively. This work paves a way to fabricate compact integrated nonlinear photonic devices in a single chip with beam dividing functions.
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Affiliation(s)
- Weijie Nie
- School of Physics, State Key Laboratory of Crystal Materials, and Key Laboratory of Particle Physics and Particle Irradiation (Ministry of Education), Shandong University, 250100 Jinan, Shandong, China
| | - Yuechen Jia
- Laboratory for Optical Systems, Department of Microsystems Engineering-IMTEK, University of Freiburg, 79110 Freiburg, Germany
| | | | - Feng Chen
- School of Physics, State Key Laboratory of Crystal Materials, and Key Laboratory of Particle Physics and Particle Irradiation (Ministry of Education), Shandong University, 250100 Jinan, Shandong, China
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Calmano T, Kränkel C, Huber G. Laser oscillation in Yb:YAG waveguide beam-splitters with variable splitting ratio. OPTICS LETTERS 2015; 40:1753-1756. [PMID: 25872065 DOI: 10.1364/ol.40.001753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this Letter, we report on laser emission from Yb:YAG beam-splitters fabricated by direct femtosecond-laser inscription. These devices consist of two adjacent mirrored s-curved waveguides merged into a section allowing for multi-mode interference (MMI) and a straight waveguide. Nine-millimeter-long one-to-two beam-splitters with radii of curvature between 10 and 80 mm have been fabricated resulting in separations between the two arms of up to 0.65 mm. Due to the MMI-section, the splitting ratio was variable by slightly changing the incoupling conditions. Maximum laser output powers of 2.29 W and slope efficiencies of 52% were achieved with the best beam-splitter waveguide laser. For all radii of curvature exceeding 10 mm, similar efficiencies were demonstrated.
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