Widely Tunable Mid-Infrared Spectral Translation in Chalcogenide Waveguide with Normal Dispersion
Chen Junming, and Guo Xiaojie
Mid-to-near-infrared spectral translation plays an important role in various applications in mid-infrared spectral range. However, the conversion efficiency and spectral tuning range were usually limited by the large frequency detuning between the pump and mid-infrared signal. In this work, a As2Se3 chalcogenide waveguide was proposed to fulfill phase matching condition in four-wave mixing with large pump-signal frequency detuning. The waveguide geometry was optimized through dispersion engineering to provide normal group velocity dispersion and negative fourth-order dispersion around 2 μm. The mid-to-near-infrared spectral translation with high efficiency and wide-band tunability was facilitated. By using a pump wavelength in the normal dispersion regime, the spectral translation and parametric amplification of mid-infrared signal ranging from 2.7 to 6.2 μm is obtained. The proposed waveguide has great potentials in high-sensitivity detection of mid-infrared signals and widely tunable mid-infrared generation.
  • Jan. 24, 2022
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 3 0323003 (2022)
  • DOI:10.3788/LOP202259.0323003
Design of Multi-Beam Lens Antenna Based on Area Mapping Method
Yang Chengfu, Xu Xinggui, Chen Junge, and Chen Juan
Multi-beam antenna technology can be used to improve the utilization of spectrum resources and channel capacity, which has attracted much attentions. Transformation optics has been widely used to design various kinds of antennas and has become a research hotspot in recent years. In this paper, an area mapping method was initiatively proposed to design a multi-beam lens antenna. The implementation method was discussed. The performance of the antenna was verified by simulation. Research results show that the designed multi-beam lens antenna based on the area mapping method can exhibit a nonmagnetic and piecewise homogeneity material parameter distributions, and can be synthesized by drilling hole in the dielectric substrate or using equivalent medium. The proposed multi-beam lens antenna can be used to reshape the radiation direction of the dipole antenna, improve the radiation gain, and achieve multi-directional radiation.
  • Jan. 24, 2022
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 3 0323002 (2022)
  • DOI:10.3788/LOP202259.0323002
Ring Resonator Pressure Sensor Based on LNOI
Ji Xiaowei, Cui Jianmin, Feng Lihui, Guo Peng, Jiang Ying, and Ji Wei
The ring resonator can be used for high precision and high sensitivity sensing. In this paper, the ring resonator is combined with cantilever pressure sensor. The expression of sensitivity of this pressure sensor is derived, the sensitivity will vary with the applied pressure. When the pressure is 1 kPa, the sensitivity is 71.73 pm/kPa. Lithium niobate on insulator (LNOI) which has low loss is used to design ring resonator to obtain a pressure sensor with high Q. It can improve the accuracy of pressure measurement. The effects of critical coupling and non critical coupling, waveguide loss and the perimeter of the ring waveguide on Q factor are discussed and analysed by Matlab. The results show that the most important factor is the waveguide loss. The increasing of the perimeter of the ring waveguide will not increase the Q factor directly, but will reduce the loss and increase the Q factor indirectly. The results show that when the radius of the ring waveguide is 80 μm and the waveguide loss is 0.6322 m-1, Q factor can reach 5.7×106.
  • Jan. 24, 2022
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 3 0323001 (2022)
  • DOI:10.3788/LOP202259.0323001
Silicon nonlinear switch as a conditional circulator for monostatic LiDAR systems
Mingfei Ding, Yiwei Xie, Hao Yan, Abu Naim R. Ahmed, Reza Safian, Swapnajit Chakravarty, Leimeng Zhuang, Pengcheng Jiao, Huan Li, Liu Liu, and Daoxin Dai
All-optical silicon-photonics-based LiDAR systems allow for desirable features in scanning resolution and speed, as well as leverage other advantages such as size, weight, and cost. Implementing optical circulators in silicon photonics enables bidirectional use of the light path for both transmitters and receivers, which simplifies the system configuration and thereby promises low system cost. In this work, to the best of our knowledge, we present the first experimental verification of all-passive silicon photonics conditional circulators for monostatic LiDAR systems using a nonlinear switch. The proposed silicon nonlinear interferometer is realized by controlling signal power distribution with power-splitting circuits, allowing the LiDAR transmitter and receiver to share the same optical path. Unlike the traditional concept requiring a permanent magnet, the present device is implemented by using common silicon photonic waveguides and a standard foundry-compatible fabrication process. With several additional phase shifters, the demonstrated device exhibits considerable flexibility using a single chip, which can be more attractive for integration with photodetector arrays in LiDAR systems.
  • Jan. 21, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000426 (2022)
  • DOI:10.1364/PRJ.444480
Flexoelectric-effect-based light waveguide liquid crystal display for transparent display
Yunho Shin, Yingfei Jiang, Qian Wang, Ziyuan Zhou, Guangkui Qin, and Deng-Ke Yang
We report a light waveguide liquid crystal display (LCD) based on the flexoelectric effect. The display consists of two parallel flat substrates with a layer of flexoelectric liquid crystal sandwiched between them. A light-emitting diode (LED) is installed on the edge of the display and the produced light is coupled into the display. When no voltage is applied, the liquid crystal is uniformly aligned and is transparent. The incident light propagates through the display by total internal reflection at the interface between the substrate and air, and no light comes out of the viewing side of the display. The display appears transparent. When a voltage is applied, the liquid crystal is switched to a micrometer-sized polydomain state due to flexoelectric interaction and becomes scattering. The incident light is deflected from the waveguide mode and comes out of the viewing side of the display. We achieved thin-film-transistor active matrix compatible driving voltage by doping liquid crystal dimers with large flexoelectric coefficients. The light waveguide LCD does not use polarizers as in conventional LCDs. It has an ultrahigh transmittance near 90% in the voltage-off state. It is very suitable for transparent display, which can be used for head-up display and augmented reality display.
  • Jan. 21, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000407 (2022)
  • DOI:10.1364/PRJ.426780
Directional emission in X-cut lithium niobate microresonators without chaos dynamics
Ang Gao, Chen Yang, Likun Chen, Ru Zhang, Qiang Luo, Wei Wang, Qitao Cao, Zhenzhong Hao, Fang Bo, Guoquan Zhang, and Jingjun Xu
We systematically investigate the field distribution of the transverse electric modes in X-cut lithium niobate disks as an example of circular microcavities with anisotropic refractive index. A conserved quantity is discovered, which indicates the absence of chaos that generally exists in deformed microcavities and leads to a nontrivial directional emission. The emission directionality was theoretically investigated and experimentally verified by exciting high-order modes of an X-cut lithium niobate microresonator assisted with second harmonics. The field distribution analysis can enrich the knowledge in designing photonic devices that need precise control of field distribution, such as phase matching in nonlinear processes. Furthermore, the discovered emission phenomenon is momentous in enhancing and controlling communications between on-chip photonic devices.
  • Jan. 13, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000401 (2022)
  • DOI:10.1364/PRJ.447488
Micro-LED backlight module by deep reinforcement learning and micro-macro-hybrid environment control agent
Che-Hsuan Huang, Yu-Tang Cheng, Yung-Chi Tsao, Xinke Liu, and Hao-Chung Kuo
This paper proposes a micro-LED backlight module with a distributed Bragg reflector (DBR) structure to achieve excellent micro-LED backlight module quality and uses deep reinforcement learning (DRL) architecture for optical design. In the DRL architecture, to solve the computing environment problems of the two extreme structures of micro-scale and macro-scale, this paper proposes an environment control agent and virtual-realistic workflow to ensure that the design environment parameters are highly correlated with experimental results. This paper successfully designed a micro-LED backlight module with a DBR structure by the abovementioned methods. The micro-LED backlight module with a DBR structure improves the uniformity performance by 32% compared with the micro-LED backlight module without DBR, and the design calculation time required by the DRL method is only 17.9% of the traditional optical simulation.
  • Jan. 05, 2022
  • Photonics Research
  • Vol.10 Issue, 2 02000269 (2022)
  • DOI:10.1364/PRJ.441188
Mag-Optical Modulator Based on Parity-Time Symmetric Structure
Yi Lingjun, and Li Changhong
A mag-optical modulator based on periodic parity-time (PT) symmetry structure is proposed, which consists of hydro-based MnFe2O4 magnetofluid layer in the middle and periodic PT symmetry units on both sides. The high extinction ratio modulation with gain is realized by using the magneto-optic effect of the magnetic fluid. The transfer matrix method is used to simulate and analyze the structure, it turns out that, for the incident light wave whose wavelength is in the low transmission region of the structure gap band(in the wavelength range from 1513 nm to 1587 nm with 1550 nm as the center), the maximum gain of the modulator for incident light is close to 25 dB, the maximum and the minimum extinction ratio are close to 60 dB and 30 dB, respectively. Simultaneously, the average modulation sensitivity of incident light wave transmission and wavelength shift can reach the maximum of 74.51 dB and 108.2 nm, respectively.
  • Dec. 29, 2021
  • Acta Optica Sinica
  • Vol.42 Issue, 2 0223001 (2022)
  • DOI:10.3788/AOS202242.0223001
Design and Optimization of Half-Adder Based on Two-Dimensional Photonic Crystal
Zhang Yan, Li Mengfan, and Chen Deyuan
In this study, line defects and point defects are introduced in a complete two-dimensional triangular lattice silicon. Using waveguide coupling and linear interference, an all-optical half-adder structure based on photonic crystal is proposed. The half-adder consists of waveguide beam splitters, an all-optical logic AND gate and an all-optical logic XOR gate. Using Rsoft software, combined with the plane-wave-expansion method and the finite-difference time-domain method, the proposed half-adder is simulated. Results show that the contrast ratios of the "carry" and "sum" ports of the proposed half-adder are 4.67 dB and 10.77 dB when the input-light wavelength is 1530 nm, and the response time is about 2.67 ps. In order to improve the contrast ratio of the "carry" port, the structure of the half-adder is optimized. The contrast ratios of the "carry" and "sum" ports of the optimized half-adder are 8.26 dB and 15.34 dB, respectively, and the response time is 3.67 ps. Theoretically, it can reach a data transmission rate of 0.273 Tbps. The proposed half-adder with optimized structure has the characteristic of high contrast ratio, and plays an important role in all-optical signal processing systems and integrated optical circuits.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 1 0123001 (2022)
  • DOI:10.3788/LOP202259.0123001