Contents
2020
Volume: 18 Issue 10
18 Article(s)

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Research Articles
Biomedical Optics
Automated superpixels-based identification and mosaicking of cone photoreceptor cells for adaptive optics scanning laser ophthalmoscope
Yiwei Chen, Yi He, Jing Wang, Wanyue Li, Lina Xing, Feng Gao, and Guohua Shi
Chinese Optics Letters
  • Publication Date: Aug. 05, 2020
  • Vol.18 Issue, 10 101701 (2020)
Tomography-assisted Doppler photoacoustic microscopy: proof of concept
Xinkun Wang, Kedi Xiong, Xin Jin, and Sihua Yang
Chinese Optics Letters
  • Publication Date: Sep. 03, 2020
  • Vol.18 Issue, 10 101702 (2020)
Diffraction and Gratings
New kind of Hermite–Gaussian-like optical vortex generated by cross phase
Chen Wang, Yuan Ren, Tong Liu, Linlin Chen, and Song Qiu
Chinese Optics Letters
  • Publication Date: Aug. 07, 2020
  • Vol.18 Issue, 10 100501 (2020)
Fiber Optics and Optical Communications
Hybrid tilted fiber gratings-based surface plasmon resonance sensor and its application for hemoglobin detection
Yarien Moreno, Qingguo Song, Zhikun Xing, Yuezhen Sun, and Zhijun Yan
We proposed a hybrid tilted fiber gratings (polarizing grating and tilted fiber Bragg grating)-based surface plasmon resonance (SPR) sensor. The hybrid tilted fiber grating, consisting of a polarizing grating and tilted fiber Bragg grating (TFBG), is fabricated in a single-mode fiber in series by using a UV-inscription technique, in which the TFBG could generate a dense cladding mode resonance to excite SPR and the polarizing grating could filter out the S-polarization cladding mode of the TFBG. Such proposed hybrid tilted fiber gratings could greatly simplify the interrogation system of the TFBG-based SPR sensor. The experiment results showed that the hybrid tilted fiber gratings-based SPR sensor has the refractive index sensitivity of 522.8 nm/RIU. Finally, by using the proposed sensor, we have achieved the hemoglobin concentration detection within a sensing range from 0.1 mg/mL to 1.0 mg/mL and the sensitivity of 8.144 nm/(mg/mL).
Chinese Optics Letters
  • Publication Date: Aug. 07, 2020
  • Vol.18 Issue, 10 100601 (2020)
General
Large effective aperture metalens based on optical sparse aperture system
Tiecheng Liu, Jingpei Hu, Linglin Zhu, Ruyi Zhou, Chong Zhang, Chinhua Wang, Aijun Zeng, and Huijie Huang
Chinese Optics Letters
  • Publication Date: Aug. 03, 2020
  • Vol.18 Issue, 10 100001 (2020)
Holography
Spatiotemporal double-phase hologram for complex-amplitude holographic displays
Xiaomeng Sui, Zehao He, Hao Zhang, Liangcai Cao, Daping Chu, and Guofan Jin
This Letter describes an approach to encode complex-amplitude light waves with spatiotemporal double-phase holograms (DPHs) for overcoming the limit of the space-bandwidth product (SBP) delivered by existing methods. To construct DPHs, two spatially macro-pixel encoded phase components are employed in the SBP-preserved resampling of complex holograms. Four generated sub-DPHs are displayed sequentially in time for high-quality holographic image reconstruction without reducing the image size or discarding any image terms when the DPHs are interweaved. The reconstructed holographic images contain more details and less speckle noise, with their signal-to-noise ratio and structure similarity index being improved by 14.64% and 78.79%, respectively.
Chinese Optics Letters
  • Publication Date: Aug. 03, 2020
  • Vol.18 Issue, 10 100901 (2020)
Lasers and Laser Optics
High single-pulse energy passively Q-switched laser based on Yb,Gd:SrF2 crystal
Mengfei Zhao, Cong Wang, Qianqian Hao, Zhengting Zou, Jie Liu, Xiuwei Fan, and Liangbi Su
Chinese Optics Letters
  • Publication Date: Aug. 12, 2020
  • Vol.18 Issue, 10 101401 (2020)
Fabrication of diamond ultra-fine structures by femtosecond laser
Tong Jiang, Si Gao, Zhennan Tian, Hanzhuang Zhang, and Ligang Niu
A 400 nm femtosecond laser was used to ablate the surface of a high-pressure and high-temperature diamond, and subwavelength surface micro structures with a period of 100 nm were achieved. A variety of micro-nano composite surface structures were prepared by changing the polarization direction and laser scanning direction. By dynamically adjusting the laser polarization and the laser scanning tracks, a maskless direct writing fabrication of micro-nano complex structures was realized. The micro-nano patterning on an ultra-hard and super-stabile diamond provides a new idea for the preparation of friction reducing surfaces, nano imprint transfer templates, surface enhanced Raman scattering test substrates, and micro-nano optical structures.
Chinese Optics Letters
  • Publication Date: Sep. 03, 2020
  • Vol.18 Issue, 10 101402 (2020)
Efficient phase-locking of 60 fiber lasers by stochastic parallel gradient descent algorithm
Hongxiang Chang, Jiachao Xi, Rongtao Su, Pengfei Ma, Yanxing Ma, and Pu Zhou
Chinese Optics Letters
  • Publication Date: Sep. 03, 2020
  • Vol.18 Issue, 10 101403 (2020)
Optical Design and Fabrication
Arbitrarily shaped retro-reflector by optics surface transformation | On the Cover
Fei Sun, Yichao Liu, Yibiao Yang, Zhihui Chen, and Sailing He
Chinese Optics Letters
  • Publication Date: Sep. 01, 2020
  • Vol.18 Issue, 10 102201 (2020)
Optical Sensing, Measurements, and Metrology
Low-frequency acoustic Fabry–Pérot fiber sensor based on a micromachined silicon nitride membrane
Zhiyuan Qu, Ping Lu, Yujian Li, Xin Fu, Wanjin Zhang, Deming Liu, and Jiangshan Zhang
In this Letter, a low-frequency acoustic sensor based on an extrinsic Fabry–Pérot (FP) interferometer with a silicon nitride (Si3N4) membrane is demonstrated. Using micromachining techniques, the 800 nm thick Si3N4 membrane is deposited on an 8 mm × 8 mm × 400 μm silicon (Si) substrate. All the assembly procedures of the sensor are focused on the substrate to avoid any damage to the membrane itself, compared to general membrane transfer methods. The frequency response of the proposed sensor is discussed theoretically and experimentally demonstrated. The sensor exhibits an excellent flat response to the tested acoustic frequency range of 1 Hz to 250 Hz. The phase sensitivity is around ?152 dB re 1 rad/μPa with sensitivity fluctuation less than 0.8 dB. The frequency response characteristic shows a promising potential of the sensor in low-frequency acoustic signal sensing applications.
Chinese Optics Letters
  • Publication Date: Sep. 01, 2020
  • Vol.18 Issue, 10 101201 (2020)
High-sensitivity fiber liquid crystals temperature sensor with tiny size and simple tapered structure
Hai Zhang, Jianyu Shang, Xiujuan Liu, Weimin Sun, Feiru Wang, and Yongjun Liu
This Letter presents a new type of optical fiber probe used to detect temperature, whose structure is very simple. The optical fiber probe is filled with cholesteric liquid crystals (CLCs) whose reflected light varies with temperature. The experimental results show that the proposed sensor can achieve a temperature sensitivity of 5.64 nm/°C in the temperature range of 18–40°C. The sensor has the advantages of simple structure, low cost, and easy mass manufacture. Its size is very tiny (the tapered structure, 125 μm in maximum diameter and <300 μm in length) and it is easy to integrate and measure. Meantime, the tapered structure of the probe is also ideal for measuring small samples such as cells and microfluidic channels, which will be a promising candidate for monitoring temperature fluctuations in small spaces.
Chinese Optics Letters
  • Publication Date: Sep. 02, 2020
  • Vol.18 Issue, 10 101202 (2020)
Modified frequency-shifted interferometer: encoding wavelength into phase
Xi Chen, Ciming Zhou, Dian Fan, Li Qian, Yandong Pang, Cong Wei, Chenguang Zhao, Sijing Liang, and Yuxiao Li
Chinese Optics Letters
  • Publication Date: Aug. 26, 2020
  • Vol.18 Issue, 10 101203 (2020)
Optoelectronics
Multi-layer magnetic recording driven by a tunable laser
Xiaoqiang Zhang, Guanghao Rui, Yong Xu, Fan Zhang, Yinchang Du, Mingtao Lian, Xiaoyang Lin, Anting Wang, Hai Ming, and Weisheng Zhao
All-optical magnetization switching with features of low-power consumption and high writing speed is a promising road map to satisfy the demand for volume data storage. To promote denser and faster magnetic recording technologies, herein, all-optical helicity-dependent switching (AO-HDS) in multi-layer magnetic recording is proposed based on the chromatic aberration of an optical lens (Thorlabs’s N-BK7 plano-convex uncoated lens). The power of the incident beams and the thickness of the multi-layer magnetic recording film are designed carefully. Besides, the uniformity of this multi-layer magnetic recording is optimized. At last, a prototype system of information multiplexing based on this multi-layer magnetic recording technology is constructed as well. Flexible and controllable magnetization reversals in different layers are also demonstrated by tuning the wavelength and helicity of working beams. We believe that such a prototype system can pave the way for increasing the storage density in an effective and low-cost mode.
Chinese Optics Letters
  • Publication Date: Aug. 07, 2020
  • Vol.18 Issue, 10 102501 (2020)
Physical Optics
Double-slit interference of single twisted photons | Editors' Pick
Wen-Rong Qi, Rui Liu, Ling-Jun Kong, Zhou-Xiang Wang, Shuang-Yin Huang, Chenghou Tu, Yongnan Li, and Hui-Tian Wang
Optical orbital angular momentum (OAM) is a special property of photons and has evoked research onto the light–matter interaction in both classical and quantum regimes. In classical optics, OAM is related to an optical vortex with a helical phase structure. In quantum optics, photons with a twisted or helical phase structure will carry a quantized OAM. To our knowledge, however, so far, no experiment has demonstrated the fundamental property of the OAM at the single-photon level. In this Letter, we have demonstrated the average photon trajectories of twisted photons in a double-slit interference. We have experimentally captured the double-slit interference process of twisted photons by a time-gated intensified charge-coupled device camera, which is trigged by a heralded detection. Our work provides new perspectives for understanding the micro-behaviors of twisted particles and enables new applications in imaging and sensing.
Chinese Optics Letters
  • Publication Date: Aug. 03, 2020
  • Vol.18 Issue, 10 102601 (2020)
Quantum Optics and Quantum Information
Experimental randomness certification with a symmetric informationally complete positive operator-valued measurement | Editors' Pick
Chenxi Liu, Kun Liu, Xiaorun Wang, Luyan Wu, Jian Li, and Qin Wang
Nonlocal correlations observed from entangled quantum particles imply the existence of intrinsic randomness. Normally, locally projective measurements performed on a two-qubit entangled state can only certify one-bit randomness at most, while non-projective measurement can certify more randomness with the same quantum resources. In this Letter, we carry out an experimental investigation on quantum randomness certification through a symmetric informationally complete positive operator-valued measurement, which in principle can certify the maximum randomness through an entangled qubit. We observe the quantum nonlocal correlations that are close to the theoretical values. In the future, this work can provide a valuable reference for the research on the limit of randomness certification.
Chinese Optics Letters
  • Publication Date: Sep. 03, 2020
  • Vol.18 Issue, 10 102701 (2020)
Thin Films and Optics at Surfaces
Optical characteristics of ultrathin amorphous Ge films
Meng Guo, Hongbo He, Kui Yi, Shuying Shao, Guohang Hu, and Jianda Shao
Ultrathin Ge films with thickness of about 15 nm at different deposition temperatures were prepared by electron beam evaporation. Spectral measurement results showed that as the deposition temperature increased from 100°C to 300°C, the transmittance of the films in the wavelength range from 350 nm to 2100 nm decreased. After annealing in air at 500°C, the transmittance significantly increased and approached that of uncoated fused quartz. Based on the Tauc plot method and Mott–Davis–Paracrystalline model, the optical band gap of Ge films was calculated and interpreted. The difference in optical band gap reveals that the deposition temperature has an effect on the optical band gap before annealing, while having little effect on the optical band gap after annealing. Furthermore, due to oxidation of Ge films, the optical band gap was significantly increased to ~5.7 eV after annealing.
Chinese Optics Letters
  • Publication Date: Aug. 03, 2020
  • Vol.18 Issue, 10 103101 (2020)
Ultrafast Optics

About the Cover

The geometric shapes of the retro-reflectors are (a) an isosceles triangle, (b) a flat triangle, (c), (d) irregular surfaces, and (e) an array of isosceles triangles.