LASER CONTROLLER FOR TUNING LASER

摘要

PURPOSE: To tune a laser to a suitable resonance frequency by selecting a suitable resonance frequency from a set of resonance frequencies of a resonator and locking the laser frequency at a suitable resonance frequency. CONSTITUTION: A controller 50 generates a tunable single-frequency output signal which is connected with an optical waveguide 52. A photocoupler 53 traps a part of a signal from the waveguide 52 and delivers it to a photoelectric unit comprising a Fabry-Perot resonator 56. A photoelectric unit 54 generates an error signal on a line 60, and a lock circuit locks the laser oscillation frequency to a suitable operating frequency. The lock circuit comprises a digital processor 75 and determines a bias current for generating a different suitable operating frequency. When the laser characteristic curve is drifted, a bias current increment is generated from an integrator 70, in response to an error signal 60 and added to a derived bias current value. The total laser bias current drives a laser to oscillate at a suitable Fabry-Perot resonance frequency, thus tuning the laser to a suitable resonance frequency.