Security and coding performance of spectral phase coding

Spectral phase coding by using 0/π-phase-shift and ±π/2-phase-shift are thoroughly studied. The security vulnerability and improvement are analysed by evaluating the encoded signal. ίπ/2-phase-shift spectral phase coding can guarantee the security by hiding the optical code in the encoded signal. In addition, coding performance of both spectral phase coding techniques is investigated by measuring auto-correlation and cross-correlation properties when using a set of 7-chip and 31-chip optical codes. ±π/2-phase-shift spectral phase coding presents better coding performance. It is for the first time revealed that the coding performance of spectral phase coding is irrelevant to the properties of the optical codes.