AgGeSbTe thin film as a negative heat-mode resist for dry lithography
Xingwang Chen, Lei Chen, Ying Wang, Tao Wei, Jing Hu, Miao Cheng, Qianqian Liu, Wanfei Li, Yun Ling, and Bo Liu
An AgGeSbTe thin film is proposed as a negative heat-mode resist for dry lithography. It possesses high etching selectivity with the etching rate difference of as high as 62 nm/min in CHF3/O2 mixed gases. The etched sidewall is steep without the obvious lateral corrosion. The lithographic characteristics and underlying physical mechanisms are analyzed. Besides, results of X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy further indicate that laser irradiation causes the formation of Ge, Sb, and AgTe crystals, which is the basis of etching selectivity. In addition, the etching selectivity of Si to AgGeSbTe resist is as high as 19 at SF6/Ar mixed gases, possessing good etching resistance. It is believed that the AgGeSbTe thin film is a promising heat-mode resist for dry lithography.
  • Jan. 26, 2022
  • Chinese Optics Letters
  • Vol.20 Issue, 3 031601 (2022)
  • DOI:10.3788/COL202220.031601
Segmented pulsed discharge for metastable argon lasing medium
Zhifan Zhang, Peng Lei, Duluo Zuo, and Xinbing Wang
Direct current pulsed discharge is a promising route for producing high-density metastable particles required for optically pumped rare gas lasers (OPRGLs). Such metastable densities are easily realized in small discharge volumes at near atmospheric pressures, but problems appear when one is trying to achieve a large volume of plasma for high-power output. In this work, we examined the volume scalability of high-density metastable argon atoms by segmented discharge configuration. Two discharge zones attached with peaking capacitors were connected parallelly by thin wires, through which the peaking capacitors were charged and of which the inductance functioned as ballasting impendence to prevent discharging in only one zone. A uniform and dense plasma with the peak value of the number densities of Ar (1s5) on the order of 1013cm-3 was readily achieved. The results demonstrated the feasibility of using segmented discharge for OPRGL development.
  • Jan. 26, 2022
  • Chinese Optics Letters
  • Vol.20 Issue, 3 031408 (2022)
  • DOI:10.3788/COL202220.031408
Photonic lattice-like waveguides in glass directly written by femtosecond laser for on-chip mode conversion
Yuying Wang, Lijing Zhong, Zhi Chen, Dezhi Tan, Zaijin Fang, Yi Yang, Shengzhi Sun, Lüyun Yang, and Jianrong Qiu
We report on a conceptually new type of waveguide in glass by femtosecond laser direct writing, namely, photonic lattice-like waveguide (PLLW). The PLLW’s core consists of well-distributed and densified tracks with a sub-micron size of 0.62 µm in width. Specifically, a PLLW inscribed as hexagonal-shape input with a ring-shape output side was implemented to converse Gaussian mode to doughnut-like mode, and high conversion efficiency was obtained with a low insertion loss of 1.65 dB at 976 nm. This work provides a new freedom for design and fabrication of the refractive index profile of waveguides with sub-micron resolution and broadens the functionalities and application scenarios of femtosecond laser direct-writing waveguides in future 3D integrated photonic systems.
  • Jan. 26, 2022
  • Chinese Optics Letters
  • Vol.20 Issue, 3 031406 (2022)
  • DOI:10.3788/COL202220.031406
Sensitive carbon monoxide detection based on light-induced thermoelastic spectroscopy with a fiber-coupled multipass cell [Invited]
Xiaonan Liu, and Yufei Ma
  • Jan. 26, 2022
  • Chinese Optics Letters
  • Vol.20 Issue, 3 031201 (2022)
  • DOI:10.3788/COL202220.031201
Direct observation of zero modes in a non-Hermitian optical nanocavity array
Flore Hentinger, Melissa Hedir, Bruno Garbin, Mathias Marconi, Li Ge, Fabrice Raineri, Juan A. Levenson, and Alejandro M. Yacomotti
Zero modes are symmetry protected ones whose energy eigenvalues have zero real parts. In Hermitian arrays, they arise as a consequence of the sublattice symmetry, implying that they are dark modes. In non-Hermitian systems that naturally emerge in gain/loss optical cavities, particle-hole symmetry prevails instead; the resulting zero modes are no longer dark but feature π/2 phase jumps between adjacent cavities. Here, we report on the direct observation of zero modes in a non-Hermitian three coupled photonic crystal nanocavities array containing quantum wells. Unlike the Hermitian counterparts, the observation of non-Hermitian zero modes upon single pump spot illumination requires vanishing sublattice detuning, and they can be identified through far-field imaging and spectral filtering of the photoluminescence at selected pump locations. We explain the zero-mode coalescence as a parity-time phase transition for small coupling. These zero modes are robust against coupling disorder and can be used for laser mode engineering and photonic computing.
  • Jan. 26, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000574 (2022)
  • DOI:10.1364/PRJ.440050
High-sensitivity integrated SiN rib-waveguide long period grating refractometer
Clement Deleau, Han Cheng Seat, Olivier Bernal, and Frederic Surre
In this research, we demonstrate a high-sensitivity integrated silicon nitride long period grating (LPG) refractometer based on a rib waveguide with sinusoidally modulated width. While integrated LPG architectures typically achieve ultrahigh sensitivity only over a narrow optical bandwidth using a phase-matching turning-point optimization technique, our sensor exhibits a very high refractometric sensitivity that was designed to remain constant over a broad operational optical spectral bandwidth. The proposed design method relies on multi-modal dispersion tailoring that consists of homogenizing the spectral behaviors of both group and effective indices of the coupling modes. Experimental results are in agreement with numerical simulations, demonstrating not only a sensitivity reaching 11,500 nm/RIU but, more significantly, also that this sensitivity remains almost constant over a broad spectral range of at least 100 nm around 1550 nm. Additional advantages of the proposed sensor architecture encompass a low temperature sensitivity, down to -0.15 nm/K, and simplicity of the fabrication process. These results demonstrate the feasibility of chip-scale photonic integration to achieve both high sensitivity and large dynamic range of the proposed refractometer.
  • Jan. 26, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000564 (2022)
  • DOI:10.1364/PRJ.444825
Exceptional points and enhanced nanoscale sensing with a plasmon-exciton hybrid system
Hong Jiang, Weidong Zhang, Guowei Lu, Lulu Ye, Hai Lin, Jinglin Tang, Zhaohang Xue, Zheng Li, Haitan Xu, and Qihuang Gong
Singularities in the spectra of open systems, known as exceptional points (EPs), have been shown to exhibit nontrivial topological properties and enhanced sensitivities. Here, we propose a novel approach to realize the EPs in a plasmon-exciton hybrid system and explore their applications in enhanced nanoscale sensing technology. We consider a plasmon-exciton system composed of a gold nanorod and a monolayer WSe2. By controlling the geometric parameters of the nano-hybrid system, we obtain simultaneous coalescence of the resonance frequencies and loss rates of the hybrid system, which is a unique feature of EPs. Numerical simulations show its application in enhanced nanoscale sensing for environmental refractive indices. Our work opens the way to a new class of sensors based on EP-enhanced sensing, with intrinsic nanoscale sensitivity due to the sub-diffraction-limit size of the plasmon-exciton nano-hybrid system.
  • Jan. 26, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000557 (2022)
  • DOI:10.1364/PRJ.445855
Influence of light pattern thickness on the manipulation of dielectric microparticles by optoelectronic tweezers
Shuailong Zhang, Mohamed Elsayed, Ran Peng, Yujie Chen, Yanfeng Zhang, Steven L. Neale, and Aaron R. Wheeler
Optoelectronic tweezer (OET) is a useful optical micromanipulation technology that has been demonstrated for various applications in electrical engineering and most notably cell selection for biomedical engineering. In this work, we studied the use of light patterns with different shapes and thicknesses to manipulate dielectric microparticles with OET. It was demonstrated that the maximum velocities of the microparticles increase to a peak and then gradually decrease as the light pattern’s thickness increases. Numerical simulations were run to clarify the underlying physical mechanisms, and it was found that the observed phenomenon is due to the co-influence of horizontal and vertical dielectrophoresis forces related to the light pattern’s thickness. Further experiments were run on light patterns with different shapes and objects with different sizes and structures. The experimental results indicate that the physical mechanism elucidated in this research is an important one that applies to different light pattern shapes and different objects, which is useful for enabling users to optimize OET settings for future micromanipulation applications.
  • Jan. 26, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000550 (2022)
  • DOI:10.1364/PRJ.437528
Navigation-grade resonant fiber-optic gyroscope using ultra-simple white-light multibeam interferometry
Shuangxiang Zhao, Qingwen Liu, Yuanyuan Liu, Huilian Ma, and Zuyuan He
The miniaturization of the gyroscope is critical for spacecrafts, drones, wellbore surveys, etc. The resonant fiber-optic gyroscope (RFOG) is a competitive candidate due to its potential in both miniaturization and high resolution, while its actual performance is well below expectation because of laser-induced noise and complexity. Here we report the first navigation grade RFOG with a bias instability of 0.009°/h and an angle random walk of 0.0093°/h. The results are realized using a fiber resonator with finesse of 63 containing 100-m long fiber. Compared with the traditional RFOGs using narrow-linewidth lasers, the key feature of the proposed RFOG is that it is driven with a broadband light source. A white-light multibeam interference method is proposed to detect the Sagnac effect, representing the simplest scheme of RFOG to date. The complexity caused by multiple feedback loops and coherent noise suppression in traditional RFOG scheme is avoided. The minimal scheme and simple modulation algorithm will also promote the on-chip waveguide gyroscope.
  • Jan. 26, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000542 (2022)
  • DOI:10.1364/PRJ.443496
Silicon-integrated nonlinear III-V photonics
Weiqiang Xie, Chao Xiang, Lin Chang, Warren Jin, Jonathan Peters, and John E. Bowers
Mainstream silicon photonic integrated circuits are based on compact and low-loss silicon-on-insulator (SOI) waveguide platforms. However, monolithic SOI-based photonics provides only a limited number of functional device types. Here, to extend the on-chip capabilities, we propose a general heterogeneous integration approach to embed highly nonlinear III-V (AlGaAs) photonics into the SOI platform. We develop low-loss AlGaAs-on-SOI photonic circuits with integrated Si waveguides and showcase sub-milliwatt-threshold (∼0.25 mW) Kerr frequency comb generation in ultrahigh-Q AlGaAs microrings (Q over 106) at the telecom bands. Our demonstration complements existing mature Si photonics technology with efficient nonlinear functionalities provided by III-V and propels conventional Si photonics into emerging nonlinear photonic applications towards fully chip-based nonlinear engines.
  • Jan. 26, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000535 (2022)
  • DOI:10.1364/PRJ.446898
Optics Physics Geography All Subjects

Special lssue

Deep learning in photonics (2021)

Published

Editor (s): Zongfu Yu, Yang Chai, Li Gao, Darko Zibar

Special Issue on High Power Laser Science and Engineering 2021 (2021)

Submission Open:25 February 2021; Submission Deadline: 31 July 2021

Editor (s): Colin Danson, Jianqiang Zhu

Future Control Systems and Machine Learning at High Power Laser Facilities (2022)

Call for Papers

Editor (s): Andreas D?pp, Matthew Streeter, Scott Feister, Hyung Taek Kim, Charlotte Palmer