Optical pickup apparatus, integrated circuit, and method for controlling laser output of optical pickup apparatus

An optical pickup apparatus comprising:

• a first laser light source including
• a first laser diode configured to emit a laser beam having a first wavelength, and
• a back monitor photodetector configured to receive the laser beam emitted from the first laser diode in a backward direction, which is not a direction of an optical disc, and output a first monitor signal corresponding to a current signal flowing through the back monitor photodetector;
• a second laser light source including a second laser diode configured to emit a laser beam having a second wavelength;
• a light-receiving circuit including
• a front monitor photodetector configured to receive the laser beam emitted from the second laser diode in a forward direction, which is a direction of the optical disc, and output a second monitor signal corresponding to a current signal flowing through the front monitor photodetector,
• a switch circuit configured to be inputted with the first and the second monitor signals, and output one of the first and the second monitor signals according to a switch signal,
• a current/voltage converter circuit configured to convert into a voltage signal one of the first and the second monitor signals outputted from the switch circuit, and output the voltage signal,
• a resistor to which the first monitor signal is supplied, and
• a voltage/current converter circuit configured to convert a voltage generated across the resistor into a current signal in the same direction as a direction of the second monitor signal, and input the current signal to the switch circuit;
• a first drive circuit configured to drive the first laser diode according to the first monitor signal outputted from the light-receiving circuit;
• and
• a second drive circuit configured to drive the second laser diode according to the second monitor signal outputted from the light-receiving circuit.