A 42.7-Gb/s Integrated Balanced Optical Front End with Record Sensitivity

We have demonstrated a record sensitivity of -36.9 dBm (39 photons/bit) for a BER of 10-9 at 42.7-Gb/s using an integrated balanced optical front end. Results were obtained using optical preamplification of RZ-DPSK modulation and an external delay- interferometer. The OSNR requirement was measured to be 17. 0 dB in a 0.1 nm bandwidth.