Noise and chirp of tunable multisection DBR lasers

Abstract

A theoretical analysis is performed of the frequency noise, relative intensity moise and frequency chirp of tunable two-section and three-section DBR lasers (LDs), taking into account the nonlinear gain compression effect. For a two-section DBR LD the frequency and intensity noise is shown to depend significantly on the tuning current, particularly at low frequencies (below the GHz range) and for low and moderate values of the grating coupling coefficient. For high values of this coefficient the tuning dependence is generally negligible when the tuning is performed only through the DBR section, but it becomes significant when using the phase control current in a three-section device. Except in the vicinity of a mode jump, the frequency chirp of a DBR LD is shown to have a little dependence on the tuning current. The possibility to measure the effective linewidth enhancement factor from the high-frequency behaviour of the chirp is suggested.