Direct laser writing spiral Sagnac waveguide for ultrahigh magnetic field sensing
Dengwei Zhang, Zhihang Zhang, Heming Wei, Jianrong Qiu, and Sridhar Krishnaswamy
A high-birefringence spiral Sagnac waveguide (SSW) device fabricated via direct laser writing (DLW) using a two-photon polymerization (2PP) technique is proposed, designed, and experimentally demonstrated as an ultrahigh magnetic field sensor. The sensor comprises a Y-style tapered waveguide and an SSW containing two microfluidic channels. The SSW has a total length of ∼2.4 mm and a spiral radius of ∼200 μm. Due to the asymmetric structure, the SSW has a high birefringence of 0.016, which can be designed as a magnetic field sensor, as a magnetic fluid can be filled into the microfluidic channel changing the guiding mode and the birefringence and consequently leading to a change in phase of the interferometer when the applied magnetic field changes. The experimental results show that the proposed photonic device has a sensitivity to magnetic fields as high as 0.48 nm/Oe within a range from 10 to 100 Oe. The proposed device is very stable and easy to fabricate, and it can therefore be used for weak magnetic field detection.
  • Sep. 15, 2021
  • Photonics Research
  • Vol.9 Issue, 10 10001984 (2021)
  • DOI:10.1364/PRJ.433854
Influence of Shell Thickness on Luminescent Properties of Cu-Doped Zn-In-S/ZnS Core/Shell Quantum Dots WLEDs
Wang Xiaoqi, and Wang Cong
In this study, Cu-doped Zn-In-S/ZnS core/shell quantum dot (QD) white-light-emitting diodes (WLEDs) are prepared, and the influence of the shell thickness on their properties is investigated. With several groups of QD WLEDs, the QD ratio of green and orange light is different to measure the properties of the International Commission on illumination (CIE) color coordinates, color rendering index (CRI), correlated color temperature (CCT), and luminous efficiency (LE). It is found that the LE and CRI of thick Cu‍‍∶‍Zn-In-S/ZnS core/shell QD WLEDs are higher than those of the thin Cu‍∶‍Zn-In-S/ZnS core/shell QD WLEDs. Additionally, when the thickness of the shell increases, the stability of QDs is enhanced and the luminous efficiency is increased.
  • Sep. 14, 2021
  • Laser & Optoelectronics Progress
  • Vol.58 Issue, 17 1723003 (2021)
  • DOI:10.3788/LOP202158.1723003
Design of Low Loss Hollow-Core Anti-Resonance Fiber for 3 μm Spectral Region
Zhang Jiaqiang, Zhang Min, Yin Jinde, Lin Haifeng, and Yan Peiguang
In order to achieve low-loss and bending-resistant mid-infrared laser transmission, the ultra-low-loss hollow-core nested anti-resonant nodeless fiber is studied in the 3 μm band, and the structural parameters of the hollow-core fiber (tube thickness, outer diameter of cladding capillary, core diameter, and nested tube outer diameter) are used for numerical simulation, and the optical fiber transmission loss as low as 0.52 dB/km is achieved in the 3 μm band. By comparing the bending loss and leakage loss of the hollow core anti-resonant fiber and the hollow core nested anti-resonant nodeless fiber, it is prove that the node-less hollow core anti-resonance fiber has lower transmission loss (loss ratio up to 22.87 dB) and better bending resistance (the loss is less than 0.1 dB/m when the bending radius is 6.5 cm) than the hollow core anti-resonance fiber.
  • Sep. 14, 2021
  • Laser & Optoelectronics Progress
  • Vol.58 Issue, 17 1723001 (2021)
  • DOI:10.3788/LOP202158.1723001
Very large group delay in VHF band using coupled high temperature superconducting resonators
Tianning Zheng, Bin Wei, Fuchuan Lei, and Bisong Cao
Storing a very high frequency (VHF) band (30–300 MHz) electromagnetic wave has many potential applications, such as phase modulation, buffering, and radio frequency memory. It can be effectively achieved by applying coupled resonator-based electromagnetically induced transparency (EIT) due to its slow light effect. However, the wavelength in the VHF band is too long to design resonators, and the group delay is limited by the high resistive loss of metal. The practical application of EIT in the VHF band is still a big challenge. In this work, we propose and experimentally demonstrate EIT response in a high-temperature superconducting (HTS) microwave circuit with coupled-resonator-induced transparency. The chip size of the HTS circuit is only 34 mm×20 mm with a very low transparency frequency of 198.55 MHz. In addition, we implement very large group delay higher than 12.3 μs and 16.2 μs with working temperatures of 65 K and 50 K separately, which is much longer than the previous reported works on slow wave. The fabricated circuit is planar with working temperature about 65 K, and thus can be easily integrated into other microwave devices under the cryogenic conditions provided by a commercial portable Stirling cryocooler. Our proposed method paves a way for studying EIT in the microwave region due to the high quality factor of the HTS resonator, which has great potential use for radio-frequency memory in the future.
  • Sep. 07, 2021
  • Photonics Research
  • Vol.9 Issue, 10 10001892 (2021)
  • DOI:10.1364/PRJ.430185
Reconfigurable Mode Multiplexer Waveguide Switch Based on Phase Change Material
Lü Yuanshuai, Wang Chenggen, Yuan Wei, Zhang Guiju, and Qi Kaiyue
Based on the optical phase change material Ge2Sb2Se4Te1 and the optical waveguide structure, a reconfigurable 2×4 mode multiplexing optical switch device is proposed to improve the optical communication capacity. The device is composed of two 1×2 multiplexing switch units with a slanted waveguide structure and a 2×2 multiplexing switch unit with symmetrical structure. First, the mode transmission characteristics in the waveguide are analyzed by the mode coupling theory. Second, the optical switching device is modeled by the three-dimensional finite difference time domain method. Finally, the model is used for experimental research. The research results show that when the working wavelength is 1550 nm, the insertion loss of the 1×2 switch unit when the phase change material is in the crystalline state and the amorphous state is as low as 0.60 dB and 0.06 dB, and the extinction ratio is as high as 19.55 dB and 27.58 dB, respectively. The minimum insertion loss of the 2×4 mode multiplex switch in the entire C-band (1530--1565 nm) is 0.23 dB, and the maximum extinction ratio is 19.12 dB.
  • Sep. 03, 2021
  • Acta Optica Sinica
  • Vol.41 Issue, 17 1723001 (2021)
  • DOI:10.3788/AOS202141.1723001
Nonlinearity Problem Analysis of Target Tracking Based on Rotational Double Prisms
Zhou Yuan, Chen Ying, Jiang Guobao, Wang Zhiyou, Zou Yingchang, Fan Shixun, Fan Dapeng, and Hu Fangrong
For target tracking based on rotational double prisms, the relation between beam steering and prism rotation is nonlinear. Based on the two groups of inverse solutions of prism orientations derived using the two-step method, the directional derivative in the moving direction of the target is calculated to derive the ratio of the rotational speed of the prisms to the slewing rate of beams, which is used to discuss the requirements of tracking targets with different orientations in different moving directions for driving and controlling over prism rotation. It is found that for a given system, the requirements depend only on the deflection angle of the present target orientation and the angle between the target moving direction and the radial direction. The tangential and radial movement of the target may result in control singularity for prism rotation on the inner and outer edges of the field of regard, respectively. The requirements of target tracking for driving and controlling over the rotation of the two prisms are slightly different. There are minor differences in the analysis results based on the two groups of inverse solutions.
  • Sep. 03, 2021
  • Acta Optica Sinica
  • Vol.41 Issue, 18 1823002 (2021)
  • DOI:10.3788/AOS202141.1823002
Design of Multi-Layer Gear-Shaped Metamaterial Absorber with Broadband and High Absorption
Wang Yang, Xuan Xuefei, Zhu Lu, Zhu Jiabing, Shen Xiaobo, Wu Yan, and Gao Qiang
A multi-layer gear-shaped metamaterial absorber with broadband and high absorption is designed based on multi-scale feature structure stacking and Fabry-Perot resonance theory. The absorber is composed of two layers of media-metal gear-shaped stacks with different sizes and the finite difference time domain method is used to analyze the absorption characteristics. Numerical results reveal that the absorptivity of this absorber in the 300-4000 nm band is above 89%, the average absorptivity can reach 94%, and the absorber shows certain polarization insensitivity. In addition, under 60° oblique incidence, it can still maintain an average absorbance of 93%. From the electromagnetic field distribution at the resonance wavelength, one can see that the broadband and high absorption characteristic of this absorber is mainly attributed to Fabry-Perot resonance, surface plasmon resonance, localized surface plasmon resonance as well as hybrid coupling among them. The proposed absorber has potential application value in photovoltaic cells, invisible devices, and other fields, due to broadband and high absorption, large-angle absorption, and polarization insensitivity.
  • Sep. 03, 2021
  • Acta Optica Sinica
  • Vol.41 Issue, 18 1823001 (2021)
  • DOI:10.3788/AOS202141.1823001
A Planar Artificial Compound Eye Based on Metalens Array
ZHOU Li, ZHANG Xiaohu, LIN Xiaogang, GAO Chao, and GUO Yongcai
In order to realize an optical imaging system with light-weight, integration and large field of view, a planar artificial compound eye structure based on the utilization of a metalens array is proposed. It uses TiO2 nanopillars with different orientation angles to manipulate the electro-magnetic wave based on the grometric phase principles. It makes the surface of the metalens array and the image plane both planar, and does not need the non-spherical processing required by the traditional curved compound eyes. With the superposition of the off-axis phase onto the traditional matalens’ focusing phase, the effect produced by the illumination of the non-paraxial light beams on the imaging quality is effectively canceled and a large field of view is achieved. The designed compound eye is mainly composed of an array of 11×11 metalenses. It has the size of the 165 μm×165 μm and overall height of 18.6 μm, with the field of view of 140°×140°. The simulation results indicates that the the proposed compound eye structure achieves good image quality even under the illumination at a large off-axis angle (50°).
  • Aug. 31, 2021
  • Acta Photonica Sinica
  • Vol.50 Issue, 6 168 (2021)
  • DOI:10.3788/gzxb20215006.0623001
Performance Research and Fabrication of 1 310 nm Superluminescent Diodes with High Power
WANG Tuo, CHEN Hongmei, JIA Huimin, YAO Zhonghui, FANG Dan, JIANG Cheng, ZHANG Ziyang, LI Kexue, TANG Jilong, and WEI Zhipeng
In order to optimize the performance of the 1 310 nm superluminescent diode, such as increase the output power of the device. In this simulation, the parameters of waveguide structure, and the heat dissipation for 1 310 nm superluminescent diode with the J-type waveguide have been investigated. The research results show that the waveguide etching depth, bending angle and thickness of the insulating layer were important for achieve high power output. Based on the research results, the superluminescent diode device structure and fabrication process were optimized, and J-type superluminescent diode with a ridge width of 5 μm, a bending angle of 8°, an etching depth of 1.7 μm and an insulating layer thickness of 300 nm was prepared. The superluminescent diode with 1.5 mm straight waveguide length has realized a high output power (42.2 mW) and wide bandwidth (10 nm) under 500 mA continuous-wave operation at room temperature.
  • Aug. 31, 2021
  • Acta Photonica Sinica
  • Vol.50 Issue, 6 179 (2021)
  • DOI:10.3788/gzxb20215006.0623002
Self-Adaptive Temperature Modulation Based on Thermal Induced Phase Changing of Vanadium Dioxide
Zhao Haipeng, Zhang Xinyuan, He Yunbin, Dou Shuliang, Li Yao, Li Xiaofeng, and Zhan Yaohui
The existing radiation cooling device is not self-adaptive, that is, it can only lower the temperature but not increase the temperature. In order to achieve the dual functions of heating and cooling, and can automatically switch with the change of ambient temperature, this article focuses on an adaptive temperature regulator based on vanadium dioxide, and systematically discusses its photothermal control principles, technical bottlenecks, and implementation methods. The combination method of transmission matrix and genetic algorithm is used to design and optimize the multilayer structure integrated by the resonant cavity and the filter, and obtain the excellent photothermal control performance of solar absorption ratio of 0.1, high temperature emissivity of 0.76 and emissivity difference of 0.7. On this basis, the real-time temperature response of the optimized structure is predicted according to the actual environment, and its adaptive temperature control function is verified theoretically. This research provides an alternative solution for adaptive temperature control based on vanadium dioxide, and provides a corresponding technical reserve for the development of intelligent thermal control technology.
  • Aug. 30, 2021
  • Acta Optica Sinica
  • Vol.41 Issue, 15 1523001 (2021)
  • DOI:10.3788/AOS202141.1523001