Athermal Polysilicon Mach-Zehnder Interferometer in Bulk CMOS

This study demonstrates the first athermal polysilicon Mach-Zehnder interferometer (MZI) based on strip and subwavelength grating waveguides in commercialized bulk CMOS without any process modification. As-fabricated MZI exhibits a temperature sensitivity of ±4 pm/°C over 1500~1600 nm wavelength range with a slope of -0.055 pm/°C/nm. This wavelength filtering device is therefore immune from the temperature gradient issue arising from the nearby electronic circuits, thus is promising for practical on-chip optical interconnect and sensor applications in bulk CMOS.