2022 Vol. 5, No. 7

Cover story: Zhang L, Zhang M, Chen TN, Liu DJ, Hong SH et al. Ultrahigh-resolution on-chip spectrometer with silicon photonic resonators. Opto-Electron Adv 5, 210100 (2022).

Spectrometers are of great importance in our scientific research and daily life. However, traditional spectrometers based on free-space optics are usually cumbersome and expensive. Therefore, great efforts have been made to realize on-chip spectrometers. As it is well known, high resolution is highly desired for spectrometers used for microbiology, food monitoring, gas sensing and so on, where fine spectrum identification is required. Recently, Prof. Daoxin Dai’s group from the College of Optical Science and Engineering at Zhejiang University, China, has proposed and demonstrated an ultra-compact and ultrahigh-resolution spectrometer on silicon by using the configuration with an ultra-narrow-band filter and a wideband filter array. In particular, an ultrahigh-Q resonator with Euler bends was introduced to achieve ultra-high-resolution wavelength- selective filtering. Meanwhile, the wideband filter array was used for achieving an extended working window of the on-chip spectrometer. For the demonstrated on-chip spectrometer, the footprint is as compact as 0.35 mm2 and the resolution is as high as 0.005 nm, which is the highest for on-chip dispersive spectrometers. The working window is about 10 nm and the ratio between the working window and the resolution is as large ~2000, which is the record for spectrometers with a footprint less than 1 mm2. The proposed spectrometer breaks the bottleneck of insufficient resolution of the dispersive chip-level spectrometer. It is expected that the present ultrahigh-resolution on-chip spectrometer plays an important role in environmental monitoring, aerospace and many other fields, especially in the field of spectral analyzing in smart phones.

Back cover story: Guo YM, Zhong LB, Min L, Wang JY, Wu Y et al. Adaptive optics based on machine learning: a review. Opto-Electron Adv 5, 200082(2022).

Adaptive optics (AO) system can correct the dynamic aberrations of optical system at the speed of thousands Hz to restore the distorted wavefront. It has important applications in astronomical high-resolution imaging, laser transmission, biomedical imaging, and other fields. In recent years, with the rapid development of big data, machine learning algorithms and computing power, scientists and engineers have begun to use artificial intelligence (AI) technology to enable the transformation and upgrade of all walks of life. So, when AI and AO meet, what kind of spark can they produce? The research group of Prof. Changhui Rao from Institute of Optics and Electronics, Chinese Academy of Sciences reviews the development of AO based on machine learning. This group has been engaged in the research of high-resolution AO imaging especially solar AO for many years. Recently, they began to focus on AO based on machine learning. This paper reviews the recent progress of the intelligent AO, such as wavefront sensing, wavefront prediction and image post-processing based on machine learning. It focuses on the current key research areas and practical application difficulties of intelligent AO. This review is important for the academic community and a boom in intelligent AO research is bound to be witnessed in the near future.


2022 Vol. 5, No. 11

ISSN 2096-4579
CN 51-1781/TN
Prof. Xiangang Luo
Executive Editor-in-Chief: