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

We present a hybrid integrated 40 Gb/s DPSK receiver module with athermal free-space delay-line-interferometer (DLI) as well as the opto-electric dc-characterisation algorithm based on the Müller-Matrix analysis. It offers wideband operation of 100 nm in the C+L band, a FSR of 43 GHz, PDFS of 350 MHz, TDFS (0 – 75°C) of 0.8 GHz and a saturated differential output voltage-swing of 600 mVpp. 43 Gb/s NRZ-DPSK back-to-back system experiments demonstrated an error-free transmission and an OSNR sensitivity of 18 dB (BER=10
⁻⁹
, PRBS 2
³¹
−1).