A "dual", feed-forward + feed-back frequency control for efficient and convenient diode laser line narrowing

Poster # 163International audienceDFB diode lasers have linewidths in the MHz range. Narrowing the linewidth can be obtained by locking the diode to a frequency discriminator (Michelson interferometer,...). But the lock bandwidth has to reach 10 MHz or higher.The current-to-frequency transfer function of DFB lasers is complex: thermal effects at low frequency, carrier physics at high frequency, and a [1MHz-20MHz] transition zone in which the phase and amplitude show variations that prevent from locking in the MHz range.Adding a phase modulator in feed-forward (FF) configuration allows convenient control of the laser frequency, in excess of 15MHz, and convenient+efficient line narrowing with commercial, off the shelf components of the telecom industry