Automatic bias control circuit for injection lasers

摘要

An injection laser is automatically stabilized so that the laser operates above threshold when the laser current is modulated. The invention makes use of the fact that the laser junction voltage saturates at currents above the threshold. A signal which modulates the laser current and causes the laser current to fall below the threshold level therefore results in a change in the junction voltage. These changes in the junction voltage are monitored and used to increase the bias current so that the laser operates above threshold.