50-GHz-Spacing Athermal Mach–Zehnder Interferometer-Synchronized Arrayed-Waveguide Grating With Improved Temperature Insensitivity

We describe a technique designed to compensate for the residual temperature sensitivity of an athermal silica-based arrayed-waveguide grating (AWG) and its application to a 50-GHz-spacing multi/demultiplexer with a low loss and a wide passband. The device has a Mach-Zehnder interferometer (MZI)-synchronized configuration, in which the AWG and the MZI are athermalized with resin-filled grooves. The point is that we employ a temperature-dependent phase-generating coupler (TD-PGC) in the MZI to compensate for the second-order temperature dependence of the AWG passband wavelength. The fabricated device exhibits practical characteristics including a low loss of less than 3.5 dB and a wide 0.5-dB bandwidth of 24.1 GHz as well as a reduced wavelength variation of less than 10 pm in a - 5degC to 65degC temperature range.