Carrier heating effects in dynamic-single-frequency GaInAsP-InP laser diodes

The fully self-contained model of a laser diode (LD) under the carrier heating conditions based on the description of a nonequilibrium carrier-phonon-photon system excited by an injection in a p-i-n double heterostructure (DHS) is presented. It combines the microscopic approach to the light-carrier interaction with the macroscopic treatment of the device characteristics and does not for example involve any empirical formulation of nonlinear gain. This model is used to investigate the carrier heating effects in the CW operation, small-signal modulation response and nonlinear picosecond (ps) dynamics of a single-frequency GaInAsP-InP laser. The carrier heating induced suppression of the material gain and enhancement of the intracavity losses are shown to be important for all operational modes. In the CW performance, these effects are found to cause the saturation of lasing and blue shift of the generation wavelength. In the high-frequency response, they are established to ensure an additional mechanism of dynamical carrier-photon coupling and therefore modify the modulation behavior of an LD. For nonlinear dynamics, the carrier heating induced perturbation of the gain and losses are shown to lead to deep pulse modulation on a ps time-scale. All the numerical estimations and modeling examples are given for 1.55 μm distributed feedback (DFB) laser operating at room temperature. It is concluded that carrier heating effects are unwelcome phenomena for CW operation, but they can be engaged to improve the modulation behavior of an LD