Design and optimization of an athermal interferometer on a silicon oxycarbide-on-insulator platform

Silicon oxycarbide (SiOC) has emerged as a promising material for photonic integrated circuits; however, its relatively high thermo-optic coefficient (TOC) can cause considerable wavelength shifts with the temperature variations. In this work, we propose a design of an all-passive athermal Mach–Zehnder interferometer (MZI) based on the SiOC-on-insulator platform. Athermal operation is achieved by using waveguides with different widths in the two MZI arms to compensate for their temperature-dependent optical-path-length variations. The device parameters were optimized over the wavelength range of 1500–1600 nm while maintaining a minimum optical confinement factor of 30%. Simulations of the device performance showed that a total temperature-sensitivity variation of 15.5 pm/K could be achieved over a 100 nm spectral range near the 1550 nm region. Furthermore, the device maintains a temperature sensitivity within ±1 pm/K at 1550 nm for common-length variations of approximately ±0.3555 mm.