Chirp minimization and optimum biasing for current-modulated coupled-cavity semiconductor lasers.

Dynamic line broadening (chirping) of a single-frequency coupled- cavity semiconductor laser under direct current modulation is analyzed theoretically using a set of generalized rate equations. When the controller section is biased below threshold in a three-terminal device (or is passive as in an external-cavity device), the chirp is not significantly affected by the intercavity coupling. By contrast, when both sections are biased above threshold, the chirp can be reduced by a proper combination of the bias levels.