The semiconductor laser apparatus includes a semiconductor laser, a detection
element for detecting the intensity of the output light from the semiconductor
laser, an error detection circuit containing a gain controllable operation amplifying
circuit and a gain-fixed type control amplifying circuit connected to a next stage
to the gain controllable operation amplifying circuit, to which a semiconductor
laser drive control signal is input and an output signal of the detection element
is input as a negative feedback signal, for outputting an error signal corresponding
to a difference between the two input signals, a high-frequency signal generating
circuit for generating a high-frequency signal having a predetermined frequency,
a high-frequency signal superimposing circuit for superimposing the high-frequency
signal onto the output signal from the error detection circuit, and a laser drive
circuit for supplying a drive current to the semiconductor laser on the basis of
the output signal from the high-frequency signal superimposing circuit.
