Experimental Demonstration of Unequally Spaced PAM-4 Signal to Improve Receiver Sensitivity for 50-Gbps PON with Power-Dependent Noise Distribution

For APD or SOA pre-amplified receivers with power-dependent non-uniform noise distributions, we demonstrate an enhanced PAM-4 modulation and detection scheme with unequally spaced signal levels, achieving improved receiver sensitivity for 50-b/s/λ PON.