LASER MODE PARTITION NOISE IN LIGHTWAVE SYSTEMS USING DISPERSIVE OPTICAL FIBER

It is well known that semiconductor laser mode partition noise (LMPN) can impair the performance of high-speed digital communication links. LMPN can also impair analog optical systems, and this phenomenon has not previously been well-characterized. In this paper we present theoretical expressions for the noise spectra that result when light from a nearly single-mode or strongly multimode semiconductor laser is passed through a length of dispersive optical fiber. These results are tested experimentally. A widely used model is found to greatly overestimate the partition noise of a DFB laser; a model for the strongly multimode case is found to match experimental results for a multimode laser. It is observed that partition noise can be significant even for multimode lasers operating near the fiber dispersion minimum.