Nonlinear gain and its influence on the laser dynamics in single-quantum-well lasers operating at the first and second quantized states

The gain nonlinearity due to spectral-hole-burning in InGaAs/InP single-quantum-well lasers operating at the first and second quantized states has been investigated by third-order perturbation solution and by strong signal approximation of the density-matrix equations, respectively. Besides the higher differential gain, a smaller nonlinear gain contribution for lasing at the second quantized state is found, as compared to the first quantized state operation; hence, these improved differential gain and nonlinear gain lead to a smaller K factor, defined as the ratio of damping rate to the square of relaxation resonance frequency, and consequently a higher maximum modulation bandwidth.<
>