Author Affiliations
Abstract
1 National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
2 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
3 School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
A 2-mm-long silicon-on-insulator grating emitter with a narrow angular full width at half-maximum (FWHM) and a high sideband suppression ratio (SSR) is proposed and designed. It consists of a grating with an approximate Gaussian emission profile along the grating length, which aims to reduce the sidelobe intensity of the scanning light in the far-field, thereby improving the resolution of the longitudinal steering resolution of the light detection and ranging (lidar). Numerical analysis shows that the angular FWHM of the emitted beam could be as low as 0.026° for a grating length of 2.247 mm and the input TE-like waveguide mode at 1550 nm, and the SSR could be more than 32.622 dB. Moreover, this grating exhibits a favorable fabrication error tolerance when considering the width and length variation of the overlayer in practice. Our design offers a promising platform for realizing integrated optical phased arrays for the long-distance solid-state lidar.
grating emitter coupled-mode theory genetic algorithm Chinese Optics Letters
2022, 20(12): 121301
Author Affiliations
Abstract
1 National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
2 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
Photonic waveguide arrays provide a simple and versatile platform for simulating conventional topological systems. Here, we investigate a novel one-dimensional (1D) topological band structure, a dimer chain, consisting of silicon waveguides with alternating self-coupling and inter-coupling. Coupled mode theory is used to study topological features of such a model. It is found that topological invariants of our proposed model are described by the global Berry phase instead of the Berry phase of the upper or lower energy band, which is commonly used in the 1D topological models such as the Su–Schrieffer–Heeger model. Next, we design an array configuration composed of two dimer patterns with different global Berry phases to realize the topologically protected waveguiding. The topologically protected propagation feature is simulated based on the finite-difference time-domain method and then observed in the experiment. Our results provide an in-depth understanding of the dynamics of the topological defect state in a 1D silicon waveguide array, and may provide different routes for on-chip lightwave shaping and routing.
fiber optics fiber optics communications fiber optics imaging Chinese Optics Letters
2020, 18(5): 051301
Author Affiliations
Abstract
1 National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
2 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
Inspired by recent rapid deep learning development, we present a convolutional-neural-network (CNN)-based algorithm to predict orbital angular momentum (OAM) mode purity in optical fibers using far-field patterns. It is found that this image-processing-based technique has an excellent ability in predicting the OAM mode purity, potentially eliminating the need of using bulk optic devices to project light into different polarization states in traditional methods. The excellent performance of our algorithm can be characterized by a prediction accuracy of 99.8% and correlation coefficient of 0.99994. Furthermore, the robustness of this technique against different sizes of testing sets and different phases between different fiber modes is also verified. Hence, such a technique has a great potential in simplifying the measuring process of OAM purity.
060.2310 Fiber optics 060.2330 Fiber optics communications 060.2350 Fiber optics imaging Chinese Optics Letters
2019, 17(10): 100603
国防科学技术大学光电科学与工程学院, 湖南 长沙 410073
在高功率光纤放大器系统中,受激布里渊散射(SBS)效应由于其较低的阈值特性成为光纤放大器功率提升的首要限制因素。为了提高SBS 阈值,提出了一种基于对入射种子光同时施加相位调制和强度调制抑制SBS 的新方法。建立了光纤激光放大器中的SBS 效应激励模型对该方法进行理论仿真。仿真结果表明,该方法可以在窄线宽激光输出的条件下显著提高光纤激光放大器中的SBS 阈值,在对20 W 入射种子光同时施加100 MHz,10 V 的相位调制和10 MHz,4 ns的强度调制后,放大器输出功率可达1127.4 W,为单频光SBS阈值的18倍。
非线性光学 受激布里渊散射 相位调制 强度调制 光纤放大器