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Mitsuhashi R, Song BS, Inoue K, Asano T, Noda S. Design and fabrication of a coupled high-Q photonic nanocavity system with large coupling coefficients. OPTICS EXPRESS 2024; 32:10630-10647. [PMID: 38571269 DOI: 10.1364/oe.513508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/27/2024] [Indexed: 04/05/2024]
Abstract
In a previous work, we demonstrated a coupled cavity system where photons in one storage cavity can be transferred to another storage cavity at an arbitrary time by applying a voltage pulse to a third cavity placed in a p-i-n junction. In this work, we demonstrate methods to improve the transfer efficiency and photon lifetimes of such a coupled system. Firstly, we designed a photonic-crystal structure that achieves a large coupling coefficient without reducing the radiation quality factor compared to the previously proposed structure: The photonic-crystal design was changed to a more symmetric configuration to suppress radiation losses and then optimized using an automatic structure tuning method based on the Covariance Matrix Adaptive Evolutional Strategy (CMAES). Here we added two improvements to achieve an evolution toward the desired direction in the two-dimensional target parameter space (spanned by the coupling coefficient and the inverse radiation loss). Secondly, to improve the experimental cavity quality factors, we developed a fabrication process that reduces the surface contamination associated with the fabrication of the p-i-n junction: We covered the photonic structure with a SiO2 mask to avoid the contamination and the electrode material was changed from Al to Au/Cr to enable cleaning by a weak acid. Owing to these improvements of the cavity design and the fabrication process, the obtained system provides coupling strengths that are about three times stronger and photon lifetimes that are about two times longer, compared to the previously reported system.
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2
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Pham PV, Mai TH, Do HB, Ponnusamy VK, Chuang FC. Integrated Graphene Heterostructures in Optical Sensing. MICROMACHINES 2023; 14:mi14051060. [PMID: 37241683 DOI: 10.3390/mi14051060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/14/2023] [Accepted: 05/14/2023] [Indexed: 05/28/2023]
Abstract
Graphene-an outstanding low-dimensional material-exhibited many physics behaviors that are unknown over the past two decades, e.g., exceptional matter-light interaction, large light absorption band, and high charge carrier mobility, which can be adjusted on arbitrary surfaces. The deposition approaches of graphene on silicon to form the heterostructure Schottky junctions was studied, unveiling new roadmaps to detect the light at wider-ranged absorption spectrums, e.g., far-infrared via excited photoemission. In addition, heterojunction-assisted optical sensing systems enable the active carriers' lifetime and, thereby, accelerate the separation speed and transport, and then they pave new strategies to tune high-performance optoelectronics. In this mini-review, an overview is considered concerning recent advancements in graphene heterostructure devices and their optical sensing ability in multiple applications (ultrafast optical sensing system, plasmonic system, optical waveguide system, optical spectrometer, or optical synaptic system) is discussed, in which the prominent studies for the improvement of performance and stability, based on the integrated graphene heterostructures, have been reported and are also addressed again. Moreover, the pros and cons of graphene heterostructures are revealed along with the syntheses and nanofabrication sequences in optoelectronics. Thereby, this gives a variety of promising solutions beyond the ones presently used. Eventually, the development roadmap of futuristic modern optoelectronic systems is predicted.
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Affiliation(s)
- Phuong V Pham
- Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - The-Hung Mai
- Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Huy-Binh Do
- Faculty of Applied Science, Ho Chi Minh City University of Technology and Education, Ho Chi Minh City 700000, Vietnam
| | - Vinoth Kumar Ponnusamy
- Department of Medicinal and Applied Chemistry and Research Center for Precision Environmental Medicine, Kaohsiung Medical University (KMU), Kaohsiung 807, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital (KMUH), Kaohsiung 807, Taiwan
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Feng-Chuan Chuang
- Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan
- Center for Theoretical and Computational Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
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Fukuda A, Asano T, Kawakatsu T, Takahashi Y, Noda S. Suppressing the sample-to-sample variation of photonic crystal nanocavity Q-factors by air-hole patterns with broken mirror symmetry. OPTICS EXPRESS 2023; 31:15495-15513. [PMID: 37157650 DOI: 10.1364/oe.488516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
It is known that the quality factors (Q) of photonic crystal nanocavities vary from sample to sample due to air-hole fabrication fluctuations. In other words, for the mass production of a cavity with a given design, we need to consider that the Q can vary significantly. So far, we have studied the sample-to-sample variation in Q for symmetric nanocavity designs, that is, nanocavity designs where the positions of the holes maintain mirror symmetry with respect to both symmetry axes of the nanocavity. Here we investigate the variation of Q for a nanocavity design in which the air-hole pattern has no mirror symmetry (a so-called asymmetric cavity design). First, an asymmetric cavity design with a Q of about 250,000 was developed by machine learning using neural networks, and then we fabricated fifty cavities with the same design. We also fabricated fifty symmetric cavities with a design Q of about 250,000 for comparison. The variation of the measured Q values of the asymmetric cavities was 39% smaller than that of the symmetric cavities. This result is consistent with simulations in which the air-hole positions and radii are randomly varied. Asymmetric nanocavity designs may be useful for mass production since the variation in Q is suppressed.
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Takata K, Kuramochi E, Shinya A, Notomi M. Improved design and experimental demonstration of ultrahigh-Q C 6-symmetric H1 hexapole photonic crystal nanocavities. OPTICS EXPRESS 2023; 31:11864-11884. [PMID: 37155812 DOI: 10.1364/oe.485093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
An H1 photonic crystal nanocavity (PCN) is based on a single point defect and has eigenmodes with a variety of symmetric features. Thus, it is a promising building block for photonic tight-binding lattice systems that can be used in studies on condensed matter, non-Hermitian and topological physics. However, improving its radiative quality (Q) factor has been considered challenging. Here, we report the design of a hexapole mode of an H1 PCN with a Q factor exceeding 108. We achieved such extremely high-Q conditions by varying only four structural modulation parameters thanks to the C6 symmetry of the mode, despite the need of more complicated optimizations for many other PCNs. Our fabricated silicon H1 PCNs exhibited a systematic change in their resonant wavelengths depending on the spatial shift of the air holes in units of 1 nm. Out of 26 such samples, we found eight PCNs with loaded Q factors over one million. The best sample was of a measured Q factor of 1.2 × 106, and its intrinsic Q factor was estimated to be 1.5 × 106. We examined the difference between the theoretical and experimental performances by conducting a simulation of systems with input and output waveguides and with randomly distributed radii of air holes. Automated optimization using the same design parameters further increased the theoretical Q factor by up to 4.5 × 108, which is two orders of magnitude higher than in the previous studies. We clarify that this striking improvement of the Q factor was enabled by the gradual variation in effective optical confinement potential, which was missing in our former design. Our work elevates the performance of the H1 PCN to the ultrahigh-Q level and paves the way for its large-scale arrays with unconventional functionalities.
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Ge R, Yan X, Liang Z, Li H, Wu J, Liu X, Chen Y, Chen X. Large quality factor enhancement based on cascaded uniform lithium niobate bichromatic photonic crystal cavities. OPTICS LETTERS 2023; 48:113-116. [PMID: 36563383 DOI: 10.1364/ol.477895] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
In this Letter, by cascading several bichromatic photonic crystals we demonstrate that the quality factor can be much larger compared with that in an isolated cavity without increasing the total size of a device. We take a lithium niobate photonic crystal as an example to illustrate that the simulated quality factor of the cascaded cavity can reach 105 with a 70° slant angle, which is an order of magnitude larger than that in an isolated cavity. The device can be fabricated easily by current etching techniques for lithium niobate. We have fabricated the proposed device experimentally including holes with ∼70° slant angle. This work is expected to provide guidance to the design of photonic crystal cavities with high quality factor.
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Wu H, Zhang H, Li F, Su W. Designing a Fano-resonance-based temperature sensor by side-coupling double cavities to waveguide in photonic crystals. APPLIED OPTICS 2022; 61:10267-10274. [PMID: 36606792 DOI: 10.1364/ao.471280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023]
Abstract
Optical sensors are widely used for temperature measurement in chemistry, biomedical detection, and food processing industries. In this paper, we present a highly sensitive temperature sensor based on the Fano resonance in two-dimensional photonic crystals. A carefully designed double cavity is used within the photonic crystals to symmetrically side-couple to a line-defect waveguide. Due to the direct and indirect coupling between two cavities, we found an asymmetric Fano-like line shape in the transmission spectrum. The optimized quality factor of the Fano resonance and the modulation depth are improved to a maximum of 10672 and above 90%, respectively. Furthermore, the sensitivity of the temperature sensor can reach as high as 91.9 pm/°C, which is direct evidence for its high sensing capability. Thus, our proposed temperature sensor has comparable quality factor and sensitivity with other reported sensors, indicating its high application potential in the sensing field.
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Song J, Feng G, Liu X, Hou H, Chen Z. Genetic Algorithm-Assisted Design of Sandwiched One-Dimensional Photonic Crystals for Efficient Fluorescence Enhancement of 3.18-μm-Thick Layer of the Fluorescent Solution. MATERIALS (BASEL, SWITZERLAND) 2022; 15:7803. [PMID: 36363395 PMCID: PMC9658013 DOI: 10.3390/ma15217803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/12/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
One-dimensional photonic crystal structures have been widely used to enhance fluorescence. However, its fluorescence enhancement is low-fold because of a weak excitation field region. In this paper, we used a genetic algorithm to assist in the design of two photonic crystals based on Al2O3 and TiO2 materials. One of them has a defect consisting of SiO2. The Fabry-Perot cavity (FP cavity) formed by the sandwiched photonic crystal achieves up to 14-fold enhancement of the excitation electric field. We modulate the electric field radiation distribution of the fluorescent material by using photonic forbidden bands. For a 3.18 μm thick layer of the fluorescent solution, the structure achieves up to 60-fold fluorescence enhancement. We also discussed that the reason for the different enhancement abilities in different places is the phase change caused by the optical path difference. This design is expected to have applications in display, imaging, etc.
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Affiliation(s)
- Jiantong Song
- Key Lab of Advanced Transducer and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Guang Feng
- Key Lab of Advanced Transducer and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xiao Liu
- Key Lab of Advanced Transducer and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Haoqiang Hou
- Key Lab of Advanced Transducer and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Zhihui Chen
- Key Lab of Advanced Transducer and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
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Mehaney A, Abadla MM, Elsayed HA. Biosensors based on novel nonlinear delta-function photonic crystals comprising weak nonlinearities. Sci Rep 2022; 12:17674. [PMID: 36271127 PMCID: PMC9586973 DOI: 10.1038/s41598-022-22210-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 10/11/2022] [Indexed: 01/18/2023] Open
Abstract
In this research, we propose a novel nonlinear delta-function photonic crystal for detecting sodium iodide (NaI) solution of different concentrations. The suggested structure comprises 50 delta stacks of GaP in an aqueous solution of NaI. These stacks are considered to have weak defocusing nonlinearity in the order of 10-6 (V/m)-2. Due to nonlinearity of the design, a defect-like resonance is formed within the photonic band gap. Thus, the detection of NaI with different concentrations can be easily investigated without the inclusion of a defect through the photonic crystal structure. The effects of both the linear part of the refractive index of GaP layers and nonlinear coefficient on the transmittance value are thoroughly discussed. The numerical findings investigate that the resonant peak begins to split at some critical nonlinearity. In our proposed structure, splitting occurs at about - 12 × 10-6 (V/m)-2. In this regard, the suggested sensor provides a high sensitivity of 409.7 nm/RIU and a wonderful detection limit of 0.0008.
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Affiliation(s)
- Ahmed Mehaney
- grid.411662.60000 0004 0412 4932TH-PPM Group, Physics Department, Faculty of Science, Beni-Suef University, Beni Suef, 62512 Egypt
| | - Mazen M. Abadla
- grid.442893.00000 0004 0366 9818Physics Department, Faculty of Science, Al-Aqsa University, Gaza, Palestinian Authority Palestine
| | - Hussein A. Elsayed
- grid.411662.60000 0004 0412 4932TH-PPM Group, Physics Department, Faculty of Science, Beni-Suef University, Beni Suef, 62512 Egypt
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Jiang X, Fan Z, Luo L, Wang L. Advances and Challenges in Heavy-Metal-Free InP Quantum Dot Light-Emitting Diodes. MICROMACHINES 2022; 13:709. [PMID: 35630176 PMCID: PMC9145869 DOI: 10.3390/mi13050709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 02/06/2023]
Abstract
Light-emitting diodes based on colloidal quantum dots (QLEDs) show a good prospect in commercial application due to their narrow spectral linewidths, wide color range, excellent luminance efficiency, and long operating lifetime. However, the toxicity of heavy-metal elements, such as Cd-based QLEDs or Pb-based perovskite QLEDs, with excellent performance, will inevitably pose a serious threat to people's health and the environment. Among heavy-metal-free materials, InP quantum dots (QDs) have been paid special attention, because of their wide emission, which can, in principle, be tuned throughout the whole visible and near-infrared range by changing their size, and InP QDs are generally regarded as one of the most promising materials for heavy-metal-free QLEDs for the next generation displays and solid-state lighting. In this review, the great progress of QLEDs, based on the fundamental structure and photophysical properties of InP QDs, is illustrated systematically. In addition, the remarkable achievements of QLEDs, based on their modification of materials, such as ligands exchange of InP QDs, and the optimization of the charge transport layer, are summarized. Finally, an outlook is shown about the challenge faced by QLED, as well as possible pathway to enhancing the device performance. This review provides an overview of the recent developments of InP QLED applications and outlines the challenges for achieving the high-performance devices.
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Affiliation(s)
- Xiaojie Jiang
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
| | - Zhen Fan
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
| | - Li Luo
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
| | - Lishuang Wang
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
- Guangxi Key Lab of Processing for Nonferrous Metals and Featured Materials and Key Lab of New Processing Technology for Nonferrous Metals and Materials, Nanning 530004, China
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Takahashi Y, Fujimoto M, Kikunaga K, Takahashi Y. Detection of ionized air using a photonic-crystal nanocavity excited by broadband light from a superluminescent diode. OPTICS EXPRESS 2022; 30:10694-10708. [PMID: 35473030 DOI: 10.1364/oe.454328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Abstract
It has been shown that silicon photonic crystal nanocavities excited by spectrally narrow light can be used to detect ionized air. Here, to increase the range of possible applications of nanocavity-based sensing, the use of broadband light is considered. We find that the use of a superluminescent diode (SLD) as an excitation source enables a more reproducible detection of ionized air. When our photonic-crystal nanocavity is exposed to ionized air, carriers are transferred to the cavity and the light emission from the cavity decreases due to free carrier absorption. Owing to the broadband light source, the resonance wavelength shifts caused by the carriers in this system (for example, due to temperature fluctuations) do not influence the emission intensity. SLD-excited cavities could be useful to determine the density of ions in air quantitatively.
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High-Sensitivity Biosensor Based on Glass Resonance PhC Cavities for Detection of Blood Component and Glucose Concentration in Human Urine. COATINGS 2021. [DOI: 10.3390/coatings11121555] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In this work, a novel structure of an all-optical biosensor based on glass resonance cavities with high detection accuracy and sensitivity in two-dimensional photon crystal is designed and simulated. The free spectral range in which the structure performs well is about FSR = 630 nm. This sensor measures the concentration of glucose in human urine. Analyses to determine the glucose concentration in urine for a normal range (0~15 mg/dL) and urine despite glucose concentrations of 0.625, 1.25, 2.5, 5 and 10 g/dL in the wavelength range 1.326404~1.326426 μm have been conducted. The detection range is RIU = 0.2 × 10−7. The average bandwidth of the output resonance wavelengths is 0.34 nm in the lowest case. In the worst case, the percentage of optical signal power transmission is 77% with an amplitude of 1.303241 and, in the best case, 100% with an amplitude of 1.326404. The overall dimensions of the biosensor are 102.6 µm2 and the sensitivity is equal to S = 1360.02 nm/RIU and the important parameter of the Figure of Merit (FOM) for the proposed biosensor structure is equal to FOM = 1320.23 RIU−1.
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Ji Y, Wang B, Fang L, Zhao Q, Xiao F, Gan X. Exciting Magnetic Dipole Mode of Split-Ring Plasmonic Nano-Resonator by Photonic Crystal Nanocavity. MATERIALS 2021; 14:ma14237330. [PMID: 34885484 PMCID: PMC8658318 DOI: 10.3390/ma14237330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 11/17/2021] [Accepted: 11/19/2021] [Indexed: 11/24/2022]
Abstract
On-chip exciting electric modes in individual plasmonic nanostructures are realized widely; nevertheless, the excitation of their magnetic counterparts is seldom reported. Here, we propose a highly efficient on-chip excitation approach of the magnetic dipole mode of an individual split-ring resonator (SRR) by integrating it onto a photonic crystal nanocavity (PCNC). A high excitation efficiency of up to 58% is realized through the resonant coupling between the modes of the SRR and PCNC. A further fine adjustment of the excited magnetic dipole mode is demonstrated by tuning the relative position and twist angle between the SRR and PCNC. Finally, a structure with a photonic crystal waveguide side-coupled with the hybrid SRR–PCNC is illustrated, which could excite the magnetic dipole mode with an in-plane coupling geometry and potentially facilitate the future device application. Our result may open a way for developing chip-integrated photonic devices employing a magnetic field component in the optical field.
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Affiliation(s)
- Yingke Ji
- Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China; (Y.J.); (B.W.); (L.F.); (F.X.)
| | - Binbin Wang
- Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China; (Y.J.); (B.W.); (L.F.); (F.X.)
| | - Liang Fang
- Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China; (Y.J.); (B.W.); (L.F.); (F.X.)
| | - Qiang Zhao
- Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
- Correspondence: (Q.Z.); (X.G.)
| | - Fajun Xiao
- Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China; (Y.J.); (B.W.); (L.F.); (F.X.)
| | - Xuetao Gan
- Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China; (Y.J.); (B.W.); (L.F.); (F.X.)
- Correspondence: (Q.Z.); (X.G.)
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Okada H, Fujimoto M, Tanaka N, Saito Y, Asano T, Noda S, Takahashi Y. 1.2-µm-band ultrahigh-Q photonic crystal nanocavities and their potential for Raman silicon lasers. OPTICS EXPRESS 2021; 29:24396-24410. [PMID: 34614686 DOI: 10.1364/oe.431721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
Nanocavity devices based on silicon that can operate in the 1.2-µm band would be beneficial for several applications. We fabricate fifteen cavities with resonance wavelengths between 1.20 and 1.23 µm. Experimental quality (Q) factors larger than one million are obtained and the average Q values are lower for shorter wavelengths. Furthermore, we observe continuous-wave operation of a Raman silicon laser with an excitation wavelength of 1.20 µm and a Raman laser wavelength of 1.28 µm. The Q values of the nanocavity modes used to confine the excitation light and the Raman scattered light are about half of those for our Raman silicon laser operating in the 1.55-µm band. Nevertheless, this device exhibits an input-output characteristic with a clear laser threshold. Finally, we consider the effect of the higher scattering probability at shorter wavelengths on the Raman laser performance in the 1.2-µm band.
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Kawakatsu T, Asano T, Noda S, Takahashi Y. Sub-100-nW-threshold Raman silicon laser designed by a machine-learning method that optimizes the product of the cavity Q-factors. OPTICS EXPRESS 2021; 29:17053-17068. [PMID: 34154256 DOI: 10.1364/oe.423470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/15/2021] [Indexed: 06/13/2023]
Abstract
Raman silicon lasers based on photonic crystal nanocavities with a threshold of several hundred microwatts for continuous-wave lasing have been realized. In particular, the threshold depends on the degree of confinement of the excitation light and the Raman scattering light in the two nanocavity modes. Here, we report lower threshold values for Raman silicon nanocavity lasers achieved by increasing the quality (Q) factors of the two cavity modes. By using an optimization method based on machine learning, we first increase the product of the two theoretical Q values by a factor of 17.0 compared to the conventional cavity. The experimental evaluation demonstrates that, on average, the actually achieved product is more than 2.5 times larger than that of the conventional cavity. The input-output characteristic of a Raman laser with a threshold of 90 nW is presented and the lowest threshold obtained in our experiments is 40 nW.
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15
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Rickert L, Fritsch B, Kors A, Reithmaier JP, Benyoucef M. Mode properties of telecom wavelength InP-based high-(Q/V) L4/3 photonic crystal cavities. NANOTECHNOLOGY 2020; 31:315703. [PMID: 32303021 DOI: 10.1088/1361-6528/ab8a8c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present finite-difference time domain simulations and optical characterizations via micro-photoluminescence measurements of InP-based L4/3 photonic crystal cavities with embedded quantum dots (QDs) and designed for the M1 ground mode to be emitting at telecom C-band wavelengths. The simulated M1 Q-factor values exceed 106, while the M1 mode volume is found to be 0.33 × (λ/n)3, which is less than half the value of the M1 mode volume of a comparable L3 cavity. Low-temperature micro-photoluminescence measurements revealed experimental M1 Q-factor values on the order of 104 with emission wavelengths around 1.55 μm. Weak coupling behavior of the QD exciton line and the M1 ground mode was achieved via temperature-tuning experiments.
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Affiliation(s)
- L Rickert
- Institute of Nanostructure Technologies and Analytics (INA), Center of Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Straße 40, Kassel 34132, Germany
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Mertin P, Römer F, Witzigmann B. Numerical analysis of subwavelength field effects in photonic crystal slab cavities. JPHYS PHOTONICS 2020. [DOI: 10.1088/2515-7647/ab60c6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Surface coupling of single quantum emitters to optical cavities consisting of a photonic crystal slab is a delicate yet crucial task for photonic quantum applications. By coupling through the evanescent surface field only small Purcell factors can be achieved. Here, we propose to introduce a pit in the slab to position the emitter closer to the mode field maximum. Photonic crystal slab L3 cavities are investigated with respect to quality factor and Purcell effect, using finite element calculations in the frequency domain. That way the spatial distribution of the Purcell factor can be calculated. Introducing a small sized pit to the surface of the photonic crystal cavity can evoke subwavelength field effects, confining the field maximum inside the pit. By engineering a pit in the center of the cavity the Purcell factor can be increased from 176 to 1331, albeit reducing the Q factor from 20769 to 16696.
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Fu Z, Sun F, Wang C, Wang J, Tian H. High-sensitivity broad free-spectral-range two-dimensional three-slot photonic crystal sensor integrated with a 1D photonic crystal bandgap filter. APPLIED OPTICS 2019; 58:5997-6002. [PMID: 31503918 DOI: 10.1364/ao.58.005997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/31/2019] [Indexed: 06/10/2023]
Abstract
We present a novel high-sensitivity broad free-spectral-range (FSR) two-dimensional three-slot photonic crystal sensor integrated with a 1D photonic crystal tapered nanobeam bandgap filter (1DPC-TNBF) based on thin-film silicon. Designed to lie in the wavelength at around 1550 nm, the resonance of the two-dimensional photonic crystal three-slot cavity (2DPC-TSC) shows strong light-matter interaction in the slot region, which enhances the bulk refractive index sensitivity of the sensor significantly. The simulated sensitivity is over 900 nm/refractive index unit (RIU). By connecting an additional 1DPC-TNBF to a 2DPC-TSC in series, the high-order modes are suppressed, which means only a fundamental mode exists with a broad FSR over 200 nm. Thus, the proposed structure is promising in designing lab-on-a-chip applications, especially in compact parallel-integrated sensor arrays.
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Asano T, Noda S. Optimization of photonic crystal nanocavities based on deep learning. OPTICS EXPRESS 2018; 26:32704-32717. [PMID: 30645432 DOI: 10.1364/oe.26.032704] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
An approach to optimizing the Q factors of two-dimensional photonic crystal (2D-PC) nanocavities based on deep learning is hereby proposed and demonstrated. We prepare a data set consisting of 1000 nanocavities generated by randomly displacing the positions of many air holes in a base nanocavity and calculate their Q factors using a first-principles method. We train a four-layer neural network including a convolutional layer to recognize the relationship between the air holes' displacements and the Q factors using the prepared data set. After the training, the neural network is able to estimate the Q factors from the air holes' displacements with an error of 13% in standard deviation. Crucially, the trained neural network can estimate the gradient of the Q factor with respect to the air holes' displacements very quickly using back-propagation. A nanocavity structure with an extremely high Q factor of 1.58 × 109 was successfully obtained by optimizing the positions of 50 holes over ~106 iterations, taking advantage of the very fast evaluation of the gradient in high-dimensional parameter spaces. The obtained Q factor is more than one order of magnitude higher than that of the base cavity and more than twice that of the highest Q factors reported so far for cavities with similar modal volumes. This approach can optimize 2D-PC structures over a parameter space of a size unfeasibly large for previous optimization methods that were based solely on direct calculations. We believe that this approach is also useful for improving other optical characteristics.
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Ashida K, Okano M, Ohtsuka M, Seki M, Yokoyama N, Koshino K, Mori M, Asano T, Noda S, Takahashi Y. Ultrahigh-Q photonic crystal nanocavities fabricated by CMOS process technologies. OPTICS EXPRESS 2017; 25:18165-18174. [PMID: 28789305 DOI: 10.1364/oe.25.018165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 07/17/2017] [Indexed: 06/07/2023]
Abstract
We fabricated photonic crystal high-quality factor (Q) nanocavities on a 300-mm-wide silicon-on-insulator wafer by using argon fluoride immersion photolithography. The heterostructure nanocavities showed an average experimental Q value of 1.5 million for 12 measured samples. The highest Q value was 2.3 million, which represents a record for a nanocavity fabricated by complementary metal-oxide-semiconductor (CMOS)-compatible machinery. We also demonstrated an eight-channel drop filter with 4 nm spacing consisting of arrayed nanocavities with three missing air holes. The standard deviation in the drop wavelength was less than 1 nm. These results will accelerate ultrahigh-Q nanocavity research in various areas.
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Maeno K, Takahashi Y, Nakamura T, Asano T, Noda S. Analysis of high-Q photonic crystal L3 nanocavities designed by visualization of the leaky components. OPTICS EXPRESS 2017; 25:367-376. [PMID: 28085831 DOI: 10.1364/oe.25.000367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We experimentally study photonic crystal L3 nanocavities whose design Q factors (Qdesign) have been improved with the visualization of leaky components design method. The experimental Q values (Qexp) are monotonically increased from 6,000 to 2,100,000 by iteratively modifying the positions of some of the air holes, as determined by the referred design method. We investigate the Qexp tolerance to imperfections in the fabricated samples, which reveals that the cavities improved by the visualization method tend to lose some tolerance to structural differences between the fabricated samples and the design values.
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Itoh T, Yamamoto YS, Ozaki Y. Plasmon-enhanced spectroscopy of absorption and spontaneous emissions explained using cavity quantum optics. Chem Soc Rev 2017; 46:3904-3921. [DOI: 10.1039/c7cs00155j] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The purpose of this tutorial review is to provide a comprehensive explanation of all types of plasmon-enhanced spectroscopies by cavity quantum optics.
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Affiliation(s)
- Tamitake Itoh
- Nano-Bioanalysis Research Group
- Health Research Institute
- National Institute of Advanced Industrial Science and Technology (AIST)
- Takamatsu
- Japan
| | - Yuko S. Yamamoto
- Research Fellow of the Japan Society for the Promotion of Science
- Chiyoda
- Japan
- Department of Advanced Materials Sciences
- Faculty of Engineering
| | - Yukihiro Ozaki
- Department of Chemistry
- School of Science and Technology
- Kwansei Gakuin University
- Sanda
- Japan
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