A 5-bit photonic analog-to-digital conversion under a sampling rate of 10 Gs/s is experimentally demonstrated. In the experiment, the birefringence walk-off in the scheme is compensated, and 16 high-extinction ratio optical transfer functions with different phase shifts are obtained. A 1-GHz sinusoidal analog signal is sampled and quantized by optical processing, and the effective number of bits obtained is 4.17.