Mid-infrared germanium photonic crystal cavity

Ting-Hui Xiao, Ziqiang Zhao, Wen Zhou, Mitsuru Takenaka, Hon Ki Tsang, Zhenzhou Cheng, and Keisuke Goda

Index: 10.1364/OL.42.002882

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Abstract

The mid-infrared (MIR) spectral range holds significant potential for spectroscopic and sensing applications because it encompasses the fingerprint region that unveils the vibrational and rotational signatures of molecules. CMOS-compatible on-chip devices that can achieve strong light-matter interaction in the entire fingerprint region are considered a promising way for such applications, but remain unprecedented. Here we present an on-chip MIR germanium photonic crystal cavity that covers the entire fingerprint region. This is made possible by harnessing a homemade air-cladding germanium platform. Our MIR device creates a new avenue toward integrated nonlinear optics and on-chip biochemical sensing in the fingerprint region.