Inverse design for material anisotropy and its application for a compact X-cut TFLN on-chip wavelength demultiplexer

Inverse design focuses on identifying photonic structures to optimize the performance of photonic devices.Conventional scalar-based inverse design approaches are insufficient to design photonic devices of anisotropic materials such as lithium niobate(LN).To the best of our knowledge,this work proposes for the first time the inverse design method for anisotropic materials to optimize the structure of anisotropic-material based photonics devices.Specifically,the orientation dependent properties of anisotropic materials are included in the adjoint method,which provides a more precise prediction of light propagation within such materials.The proposed method is used to design ultra-compact wavelength division demultiplexers in the X-cut thin-film lithium niobate(TFLN)platform.By benchmarking the device performances of our method with those of classical scalar-based inverse design,we demonstrate that this method properly addresses the critical issue of material anisotropy in the X-cut TFLN platform.This proposed method fills the gap of inverse design of anisotropic materials based photonic devices,which finds prominent applications in TFLN platforms and other anisotropicmaterial based photonic integration platforms.

A Clinical Observation Report on Prenatal Management and Postnatal Treatment of Congenital Granular Cell Epulis

Introduction Congenital granular cell epulis(CGCE)is a rare,benign tumor that manifests on the mucosal surface of the alveolar ridge in newborns.It was initially described by Neumann in 1871 and has been referred to by various names such as congenital epulis,congenital epulis of the newborn,and congenital granular cell tumor.1 Documentation on larger tumors is limited and reported diameters vary.2 Diagnosis necessitates histological examination and immunohistochemical staining,typically revealing negative immunoreactivity for S-100 and cluster of differentiation 68(CD68).3,4 This article presents a case of CGCE with weakly positive S-100 and CD68 staining,alongside a relatively large size.Additionally,it conducts a literature review on diverse aspects,encompassing multidisciplinary prenatal diagnosis,antenatal management,choice of delivery mode during childbirth,and postnatal treatment,with the objective of augmenting clinicians’comprehension of the ailment.The study adhered to the guidelines of the Declaration of Helsinki and obtained informed consent from the patient and approval from the medical ethics committee of Chongqing Health Center for Women and Children.

Fault diagnosis of silage harvester based on a modified random forest

The objective of this study is to investigate the effectiveness of a multi-parameter intelligent fault diagnosis method based on a modified random forest algorithm(RFNB algorithm),so as to reduce the impact of blockage fault on the operation of a silage harvester,thus providing a reference for the intelligent control.In brief,the forward speed,cutting speed,engine speed and engine load were selected as the input variables.Then,a random forest(RF)was used to construct a naive Bayes classifier for each node of the decision tree,and finally the RFNB algorithm constituted based on the naive Bayes tree(NBTree).The results revealed that by improving the classification accuracy of a single decision tree,the fault diagnosis accuracy of the entire RF was improved.When the sample data were consistent,the accuracy of the RFNB algorithm was 97.9%,while that of the RF algorithm was only 93.27%.Besides,the performance of RFNB classifiers was significantly better than that of RF classifiers.In conclusion,the RFNB model can accurately identify the fault status of the silage harvester with its good robustness,which provides a new idea for the fault monitoring and early warning of large agricultural rotating machinery in the future.

Reflection sensitivity of dual-state quantum dot lasers

This work experimentally and theoretically demonstrates the effect of excited state lasing on the reflection sensitivity of dual-state quantum dot lasers,showing that the laser exhibits higher sensitivity to external optical feedback when reaching the excited state lasing threshold.This sensitivity can be degraded by increasing the excited-to-ground-state energy separation,which results in a high excited-to-ground-state threshold ratio.In addition,the occurrence of excited state lasing decreases the damping factor and increases the linewidth enhancement factor,which leads to a low critical feedback level.These findings illuminate a path to fabricate reflectioninsensitive quantum dot lasers for isolator-free photonic integrated circuits.

一类基于Robin边界条件变化的反传输特征值问题

本文研究具有Robin边界条件的Schrodinger算子反传输特征值问题,旨在由传输特征值数据还原势函数.通过改变其中一个边界条件参数,可以获得有无穷多个能量有限的传输特征值.本文证明这样的传输特征值集合可以唯一地确定Schrodinger算子的势函数及另一个边界条件参数.

Mid-infrared silicon photonic waveguides and devices [Invited]

Silicon has been the material of choice of the photonics industry over the last decade due to its easy integration with silicon electronics, high index contrast, small footprint, and low cost, as well as its optical transparency in the nearinfrared and parts of mid-infrared(MIR) wavelengths(from 1.1 to 8 μm). While considerations of micro-and nano-fabrication-induced device parameter deviations and a higher-than-desirable propagation loss still serve as a bottleneck in many on-chip data communication applications, applications as sensors do not require similar stringent controls. Photonic devices on chips are increasingly being demonstrated for chemical and biological sensing with performance metrics rivaling benchtop instruments and thus promising the potential of portable, handheld,and wearable monitoring of various chemical and biological analytes. In this paper, we review recent advances in MIR silicon photonics research. We discuss the pros and cons of various platforms, the fabrication procedures for building such platforms, and the benchmarks demonstrated so far, together with their applications. Novel device architectures and improved fabrication techniques have paved a viable way for realizing low-cost, high-density,multi-function integrated devices in the MIR. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems.

Quasi-vertical tapers for polymer-waveguide-based interboard optical interconnects

A mode transformer based on the quasi-vertical taper is designed to enable high coupling efficiency for interboardlevel optical interconnects involving single-mode polymer waveguides and standard single-mode fibers. A triangular region fabricated above the waveguide is adopted to adiabatically transform the mode from the fiber into the polymer waveguide. The effects of the geometrical parameters of the taper, including width, height, tip width,etc., on the coupling efficiency are numerically investigated. Based on this, a quasi-vertical taper for the polymer rib waveguide system is designed, fabricated, and characterized. Coupling losses of 1.79 0.30 and 2.23 0.31 dB per coupler for the quasi-TM and quasi-TE mode, respectively, are measured across the optical communication C and L bands(1535 to 1610 nm). Low-cost packaging, leading to widespread utilization of polymeric photonicdevices, is envisioned for optical interconnect applications.