Improvement of Photonic ADC Based on Phase-Shifted Optical Quantization by Using Additional Modulators

An improvement of a photonic analog-to-digital converter based on phase-shifted optical quantization (PSOQ) is presented and verified. The resolution can be increased by employing an additional Mach-Zehnder modulator (MZM) to combine with the PSOQ scheme. The improved scheme with a quantization level of 32 (corresponding quantization bit number is 5 bits) is experimentally demonstrated by using two LiNbO
₃
modulators, and the experimental result with the effective number of bits 4.23 is obtained.