Semiconductor laser chirping-induced dispersive distortion in high-bit-rate optical fiber communications systems

Modulation characteristics of single-longitudinal-mode semiconductor lasers are sufficiently well understood to permit meaningful modeling of high-bit-rate dispersive optical fiber communications systems. Semiconductor laser modulation dynamics are briefly reviewed with an emphasis on the interdependence of wavelength chirping and damping of relaxation oscillations. Beginning with the basic equations governing the laser optical field, computer simulations are described which evaluate the system ´eye closure´ resulting from chirping and related laser modulation constraints. The effects of laser structure, parasitics and intentional transmitter and receiver current filtering are explored. Tolerances for deviation from the zero dispersion wavelength are estimated for bit rates up to 16 Gb/s. The analysis indicates that proper choice of linear transmitter and receiver filtering can significantly reduce degradation resulting from inherently nonlinear chirping-induced dispersive distortion.<>