Power level controlled optical sweep oscillator using a GaAs semiconductor laser

A frequency-tunable semiconductor laser having a power level controller has been developed. The laser frequency is locked to a piezoelectrically modulated interferometer having a free spectral range of 5 GHz and tuned by varying its mirror gap. A servoloop for this purpose is connected to the injection current source of the laser diode. The level of the output power is stabilized by a second servoloop connected to the temperature controller of the laser diode. The relations between the parameters of the servoloops and the characteristic of the laser diode to get a good system response are discussed.