New unipolar codes allowing electrooptical correlation utilizing a semiconductor laser amplifier

This letter reports on the development of a new code allowing the use of a semiconductor laser amplifier (SLA) to execute correlation in the optical domain. Semiconductor laser amplifiers act as AND gates and can only correlate codes in the unipolar domain and therefore have been limited by the lack of unipolar codes with good autocorrelation properties. The authors propose a new unipolar code derived from bipolar Golay codes which has a high probe duty cycle (50%) and is ideal for use with an SLA based correlator. Computer modeling of an SLA correlator used to interrogate a sensor network is described, indicating crosstalk levels of less than 0.7%.