Optical coherent receivers for 2.5 and 5 Gb/s

We present coherent optical detection with high sensitivity for fiber-optic and free-space applications. The system can operate at 840 nm, 1064 nm, 1310 nm, and in the S, L and C bands. We show the sensitivity improvement of balanced detection for non-return-to-zero on/off keying (NRZ-OOK) at 2.5 Gb/s and 5 Gb/s compared to single-ended detection.