All optical analog-to-digital converters (ADC) are key devices in high speed signal processing. The frequency response characteristic of all optical ADC based on polarization-differential interference and phase-shifted optical quantization (PSOQ) is experimentally demonstrated. Different frequency sinusoidal signals are quantized by a 4 bit photonic ADC. The frequency spectra of digital signals are obtained and analyzed by discrete Fourier transform. The results show that the rang of frequency response is from 74.07 dB to 74.22 dB. The fluctuation of the frequency response is less than 0.15 dB. Then a 1 GHz triangular waveform is sampled and all-optical quantized, and the effective number of bits (ENOB) of 3.31 bit is obtained. The experimental results show that the frequency response of the PSOQ is better, and the application of PSOQ in arbitrary waveform is feasible.