Mid-infrared Silicon Microphotonic Cavities with High Resonance of Q~10^5

P.T. Lin, V. Singh, Y. Cai, N.S. Patel, L. Kimerling, A.M. Agarwal
Massachusetts Institute of Technology, US

Keywords: mid-infrared, group IV materials, photonic circuits

Summary:

One dimensional photonic crystal 1D-PhC silicon waveguide resonators with quality factor, Q~10^5, are demonstrated at mid-infrared wavelengths between 2 um to 5 um. Silicon has several advantages for mid-infrared applications including its broad mid-infrared transmission spectrum which extends out to 9 um, CMOS compatible fabrication processing, and ease of electronic-photonic integration. The proposed resonators are composed of photonic crystal cavities with optimized (i) lattice parameter a, (ii) cavity width w and (iii) hole radius r. Finite difference time domain (FDTD) simulations are used to adjust these three parameters, a, w, and r, to select a resonant frequency of interest within the mid-infrared spectral range. Due to the high quality factor Q, these PhC silicon waveguide resonators have much higher sensitivity as chemical sensors and have the potential to replace bulky instruments such as an Fourier transform infrared spectroscopy (FTIR).