Integrated 40 Gb/s DPSK receiver module for C+L band with athermal free-space delay-line-interferometer

We present a 40Gb/s DPSK receiver module with athermal free-space DLI. It offers wideband operation in the C+L band, a FSR of 43GHz, PDFS of 350MHz, TDFS (0–75°C) of 0.8GHz and a differential output voltage-swing of 600mVpp. 43Gb/s NRZ-DPSK back-to-back OSNR sensitivity is 18dB (PRBS 2 31 –1).