Relationship Between Carrier-Induced Index Change and Feedback Noise in Diode Lasers

An improved theoretical analysis of single-mode diode laser dynamics reveals that feedback-induced intensity pulsations and frequency modulation are consequences of the carrier-dependent modal refractive index of the laser cavity. A stability criterion based on injection-locking theory indicates that gain-guided diode lasers are more likely to exhibit feedback-induced pulsations than are index-guided devices. Numerical simulation of feedback-induced noise is shown to be in excellent agreement with previously reported experimental data.