Highly Angular Tolerant Transmission Filters for Narrow-Band Image Sensors

作     者：Fatima Omeis Mondher Besbes Christophe Sauvan Henri Benisty Fatima Omeis;Mondher Besbes;Christophe Sauvan;Henri Benisty

作者机构：Laboratoire Charles Fabry Institut d’Optique Graduate School Université Paris Saclay CNRS Palaiseau France 

出 版 物：《Optics and Photonics Journal》 (光学与光子学期刊（英文）)

年 卷 期：2021年第11卷第6期

页      面：140-151页

学科分类：080901[工学-物理电子学] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 080401[工学-精密仪器及机械] 0804[工学-仪器科学与技术] 0803[工学-光学工程] 

主　　题：Narrow-Band Filters Transmission CMOS Angular Tolerant Subwavelength Grating Distributed Bragg Reflectors (DBR) Fabry-Perot Cavity 

摘      要：A dielectric transmittance filter composed of subwavelength grating sandwiched between two few-layers distributed Bragg reflectors (DBRs) is proposed with the aim of being compatible with CMOS technology and to be tunable by lithographic means of the grating pattern without the need of thickness changes, in the broad spirit of metamaterials. The DBR mirrors form a Fabry-Perot (FP) cavity whose resonant frequency can be tuned by changing the effective refractive index of the cavity, here, by tailoring the in-plane filling factor of the grating. The structure has been studied and designed by performing numerical simulations using Fourier Modal Method (FMM). This filter proves to have high broad angular tolerance up to ±30˚. This feature is crucial for evaluating the spectral performance of narrow-band filters especially the so-called Ambient light sensors (ALS). By analyzing the transmittance spectral distributions in the band diagram, it is found that the angular tolerance is due to coupling between the FP and the guided mode inside the cavity in analogy to resonances occurring within multimode periodic waveguides in a different context.