Characterization of polycrystalline silicon-based photonic crystal- suspended membrane for high temperature applications

We present the design and the characterization of a polycrystalline silicon (Si)-based photonic crystal (PhC)-suspended membrane, working in the mid-infrared wavelengths. In order to facilitate transmission measurement, the PhC membrane is released by removing the underneath Si substrate. Around 97% reflection and 3% transmission at 3.58-μm wavelength are measured at room temperature. Characterization is also done at 450°C and it reveals that the peak reflection of the PhC membrane shifts by 75 nm to higher wavelengths. This corresponds to a linear wavelength shift of 0.174 nm∕°C and the thermo-optic coefficient is calculated to be þ1.70 × 10−4 K−1. By altering the dimension of the PhC air holes, it is also shown that such a thermo-optic effect is compensated. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.JNP.8.084096]