Patent ID: 8837539

Claim:
An optical power stabilizing device adapted to stabilize optical power of alight emitting device that has a forward voltage, the forward voltage having an inverse relationship with an ambient temperature when driven with current, said optical power stabilizing device comprising: a current generating circuit to be coupled to the light emitting device and disposed to receive a pulse-wave signal, said current generating circuit being configured to convert the pulse-wave signal into a driving current to be provided to the light emitting device, the driving current being a pulse wave in magnitude and having an average magnitude proportional to a duty cycle of the pulse-wave signal; an optical-type feedback circuit including a photodetector that is disposed to detect light emitted by the light emitting device, and that is configured to generate a photocurrent associated with optical power of the light emitting device, said optical-type feedback circuit being configured to generate a first feedback voltage according to the photocurrent; an electrical-type feedback circuit to be coupled across the light emitting device for detecting the forward voltage of the light emitting device and the driving current, and configured to generate a second feedback voltage according to the forward voltage of the light emitting device and the driving current; and a pulse wave generating circuit coupled to said optical-type feedback circuit, said electrical-type feedback circuit and said current generating circuit, said pulse wave generating circuit being configured to generate the pulse-wave signal according to one of the first feedback voltage and the second feedback voltage, the duty cycle of the pulse-wave signal being inversely proportional to magnitude of said one of the first feedback voltage and the second feedback voltage.