Patent ID: 7242701

Claim:
Apparatus for controlling the operating wavelength of a laser to be substantially equal to a predetermined wavelength, the apparatus comprising: a laser means including the laser, a controllable current source coupled to said laser for varying the injection current supplied to the laser, and a controllable thermal element coupled to the laser for varying the temperature of the laser; a controller coupled to the laser means to monitor a set of one or more operating parameters selected from the group consisting of injection current supplied to the laser, operating temperature of the laser, operating wavelength of the laser, and output power of the laser, the controller for characterizing desired parameters of the laser by: characterizing a reference laser injection current I 0 as a function of the laser output power P out for a constant reference temperature of the laser T 0 ; characterizing a laser injection current I and a corresponding laser temperature T as a function of the laser output power P out at a constant operating wavelength substantially equal to a target wavelength λ 0 ; computing a ratio of the characterized laser injection current I 0 to the characterized laser injection current I in order to determine a relative efficiency η rel of the laser; determining a relationship between the change in laser temperature ΔT and a change in relative efficiency Δη rel for the laser when the wavelength of the laser is maintained substantially constant at least at the target wavelength λ 0 ; and storing characterizations of the reference laser injection current and the laser injection current.