All-optical processing of RZ-DPSK signals using counter-propagating pulses in a saturated SOA

We demonstrate three novel all-optical signal processing methods for RZ-DPSK signals using a saturated SOA. The two logically opposite pulse streams from a demodulated noisy RZ-DPSK signal counter-propagate in the SOA. This configuration decreases the fluctuations in the demodulated marks while preventing the spaces from getting amplified. Photonic balancing provides functionality analogous to electrical balanced detection by reducing the required OSNR, and saturated asymmetric filtering removes the in-band ASE noise before detection. These methods are demonstrated experimentally by observing eye diagrams and BER measurements at 10.7 Gb/s and 22.3 Gb/s.

Research Highlights
► Three all-optical signal processing techniques using a saturated SOA are demonstrated.
► Amplitude restoration is achieved using the SOA limiting amplification capability.
► Photonic balancing provides a 3-dB decrease in the required OSNR.
► Saturated asymmetric filtering provides an additional 2.7-dB sensitivity improvement.