Free-spectral-range-free filters with ultrawide tunability across the S+C+L band  

作　　者：CHUNLEI SUN CHUYU ZHONG MAOLIANG WEI HUI MA YE LUO ZEQUN CHEN RENJIE TANG JIALING JIAN HONGTAO LIN LAN LI 

机构地区：[1]Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province,School of Engineering,Westlake University,Hangzhou 310024,China [2]Institute of Advanced Technology,Westlake Institute for Advanced Study,Hangzhou 310024,China [3]Key Laboratory of Micro-Nano Electronics and Smart System of Zhejiang Province,College of Information Science and Electronic Engineering,Zhejiang University,Hangzhou 310027,China [4]School of Microelectronics,Zhejiang University,Hangzhou 310027,China

出　　处：《Photonics Research》2021年第6期1013-1018,共6页光子学研究（英文版）

基　　金：National Key Research and Development Program of China(2019YFB2203003);National Natural Science Foundation of China(61975179,91950204);Westlake University(the start-up fund of Westlake University).

摘　　要：Optical filters are essential parts of advanced optical communication and sensing systems.Among them,the ones with an ultrawide free spectral range(FSR)are especially critical.They are promising to provide access to numerous wavelength channels highly desired for large-capacity optical transmission and multipoint multiparameter sensing.Present schemes for wide-FSR filters either suffer from limited cavity length or poor fabrication tolerance or impose an additional active-tuning control requirement.We theoretically and experimentally demonstrate a filter that features FSR-free operation capability,subnanometer optical bandwidth,and acceptable fabrication tolerance.Only one single deep dip within a record-large waveband(S+C+L band)is observed by appropriately designing a side-coupled Bragg-grating-assisted Fabry–Perot filter,which has been applied as the basic sensing unit for both the refractive index and temperature measurement.Five such basic units are also cascaded in series to demonstrate a multichannel filter.This work provides a new insight to design FSR-free filters and opens up a possibility of flexible large-capacity integration using more wavelength channels,which will greatly advance integrated photonics in optical communication and sensing.

关 键 词：free DESIRED INSIGHT 

分 类 号：TN713[电子电信—电路与系统]