Reduction of relative intensity noise of the output field of semiconductor lasers due to propagation in dispersive optical fiber

Abstract

The effect of dispersive, linear propagation (e.g., in single-mode optical fiber) on the intensity noise from semiconductor lasers is investigated. Relations between the frequency and amplitude noise variations of semiconductor lasers are obtained from the laser rate equations and used to calculate the change in the relative intensity noise (RIN) spectrum that occurs during dispersive propagation. Propagation in fiber with positive dispersion (D>0) over moderate distances (several km for standard single-mode fiber at 1.55 mu m) is found to reduce the RIN over a wide range of frequencies. Measurements with a 1.56 mu m distributed feedback laser confirm the main theoretical results and demonstrate reductions in RIN of up to II dB with 4 km of standard fiber.