Experimental comparison of coherent versus incoherent sources in a four-user λ-t OCDMA system at 1.25 Gb/s

In optical code-division multiple access (OCDMA), the optical bandwidth is accessed simultaneously by multiple users, leading to beat noise in photodetection. The choice of the optical source can have important impact on that noise. In this paper, we compare two optical sources, a broad-band erbium-doped fiber source and a multilaser source. Experimental results for a wavelength-time OCDMA system are presented for up to four simultaneous users. Bit-error-rate curves are measured at 1.25 Gb/s with a chip rate of 10 Gchip/s. It is shown that the multilaser source outperforms the broad-band source for the design parameters of this system.