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Updated: May 31, 2026
A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Polarization insensitive 25-Gbaud direct D(Q)PSK receiver based on polymer planar lightwave hybrid integration
Jin Wang1, Crispin Zawadzki, Nelson Mettbach
1Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut, Einsteinufer 37, D-10587 Berlin, Germany. jin.wang@hhi.fraunhofer.de
Abstract:
We report a direct DPSK receiver based on polymer planar lightwave circuit technology, which incorporates a 2x25 GHz photodiode (PD) array hybridly integrated via 45° mirrors. In this direct DPSK receiver, a half-wave plate and heating electrodes are implemented to eliminate the polarization-dependent frequency-shift (PDFS) of the delay-line interferometer (DLI). By applying a proper heating current, a residual PDFS of practically zero at 1550 nm and within ±125 MHz was achieved over the full C-band. Integrated with the PD array, the peak responsivity is ~0.14 A/W for orthogonal polarizations over the C-band. To characterize this direct receiver, we introduce an adapted common-mode rejection ratio (CMRR), which takes into account the unequal responsivities of the PDs, the uneven split of the input power by the DLI, the phase error and the extinction ratio of the DLI. The measured CMRR under DC condition is below -20 dB over the C-band.
