Subwavelength grating waveguide-integrated athermal Mach-Zehnder interferometer with enhanced fabrication error tolerance and wide stable spectral range

We propose an athermal Mach-Zehnder interferometer (MZI) with a subwavelength grating waveguide implemented in one of the arms to increase its fabrication error tolerance. The design is demonstrated with a CMOS compatible fabrication. In this work we will discuss the design principles of the subwavelength grating, loss mechanism, fabrication procedure and experimental results obtained. The fabricated devices have a temperature sensitivity of less than 10 pm/K over a spectral range from 1.5μm to 1.64μm. Also, the fabricated devices have a stable performance within the aforementioned specifications even with fabrication linewidth variations from -20 nm to 40 nm.