Affiliation:
1. Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province School of Engineering Westlake University Hangzhou 310030 China
2. Institute of Advanced Technology Westlake Institute for Advanced Study Hangzhou 310024 China
3. State Key Laboratory of Modern Optical Instrumentation Key Laboratory of Micro‐Nano Electronics and Smart System of Zhejiang Province College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China
Abstract
AbstractOn‐chip free spectral range (FSR)‐free optical filter with a compact footprint is crucial for developing emerging sensing applications, as it allows for the optimal utilization of extensive optical bandwidth. Despite being an important area of technology, on‐chip optical sensing system has faced challenges in channel count, particularly due to the limited FSR, large footprint, and loss of the wavelength‐selective filter unit. To address these challenges, a scalable nanobeam cavity prototype with a length of ≈21 µm based on the asymmetric Bragg mirrors is presented. By engineering the band structure of the nanobeam cavity, the stopband can be flexibly tuned to achieve an FSR‐free spectral response within 350 nm. Two 25‐nanobeam‐cavity arrays are fabricated with a footprint of 215 × 120 µm2 and an average insertion loss of ≈3.2 dB over a broad wavelength range. To the best of the authors’ knowledge, this is the largest‐channel‐count multiplexed micro‐cavity array on a single waveguide, reported to date. As a proof‐of‐principle application, the 2D high‐spatial‐resolution temperature distribution sensing is experimentally demonstrated. This work provides new insight into the design of ultra‐compact FSR‐free filters and will give birth to numerous charming applications that make use of the broad bandwidth capabilities of optics while occupying minimal space.
Funder
Natural Science Foundation of Zhejiang Province
Innovative Research Group Project of the National Natural Science Foundation of China
Subject
Condensed Matter Physics,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials