Monolithic Integration of CMOS Temperature Control Circuit and Si3N4 Microring Filters for Wavelength Stabilization Within Ultra Wide Operating Temperature Range

Microring resonators are widely used for both active and passive devices for their small footprint and low- power consumption. However, it is very challenging to achieve precise control of stability of the resonant wavelength, as the microring is very sensitive to fabrication imperfections and temperature variations. In this paper, we propose and demonstrate a new method of monolithic integration of complementary metal-oxide-semiconductor (CMOS) temperature control circuit and Si ₃ N ₄ microring filters for resonant wavelength stabilization. Through CMOS back-end process, Si ₃ N ₄ photonic layer is formed vertically above the CMOS circuit chip. Due to the automatic temperature control, the integrated Si ₃ N ₄ microring filters are almost immune to environment temperature change. The temperature-dependent wavelength shift (TDWS) is decreased from 21.43 pm/°C to 1.43 pm/°C with the environment temperature tuning range from 30 °C to 65 °C.