Silicon-on-Insulator Waveguide Devices for Broadband Mid-Infrared Photonics

• Published in: IEEE photonics journal 2017-06, Vol.9 (3), p.1-10
• Main Authors: Dong, Bowei, Guo, Xin, Ho, Chong Pei, Li, Bo, Wang, Hong, Lee, Chengkuo, Luo, Xianshu, Lo, Guo-Qiang
• Format: Article
• Language: English
• Subjects: Couplings; Integrated optics materials; mid infrared; Optical device fabrication; Optical losses; Optical waveguides; photonic integrated circuits; Photonics; Propagation losses; Silicon; waveguides
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2017.2692039

In this paper, we demonstrate silicon-on-insulator (SOI) channel waveguides with propagation loss and r = 10  \mu\text{m} bends with bending loss as low as 2 dB/cm and 0.02 dB/90 ^{\circ } in the broad wavelength range of 3.68-3.88 \mu \text{m}. We also indicate the limitation of SOI waveguide loss in mid-infrared wavelength by analyzing loss mechanisms. Based on this high-performance mid-infrared waveguide, we systematically analyze the coupling efficiency of various directional couplers, which are critical and commonly used building blocks for on-chip light routing and power splitting. By varying coupling length and sweeping wavelength, the performance of directional coupler with various gap separations is meticulously investigated in 3.68-3.88 \mu \text{m}. A experimental database for directional coupler with any power splitting ratio is provided. Our results offer a promising broadband platform for dense wavelength division multiplexing (DWDM) and applications that require precise control of coupling such as racetrack resonator in the mid-infrared region.