Patent ID: 7012938

Claim:
A laser device comprising: a laser diode; and a controller that superimposes a low-frequency signal on a modulating signal applied to the laser diode, the low-frequency signal having an amplitude that correlates with an amplitude of the modulating signal wherein the controller comprises: an amplitude monitor part that monitors the amplitude of the low-frequency signal contained in laser light emitted by the laser diode and generates a first voltage based on a monitored amplitude of the low-frequency signal; a voltage output part that generates a second voltage that corresponds to a difference between the first voltage and a first reference voltage; a pilot signal output part that generates a pilot signal having a low frequency and an amplitude based on the second voltage; an adder part that adds the pilot signal and the second voltage with a given ratio; and a modulating signal output part that controls the amplitude of the modulating signal on the basis of the second voltage with the pilot signal being added thereto and thus supplies the laser diode with the modulating signal with the low-frequency signal being superimposed thereon.