US 6,324,197 B1Granted

Power controller for semiconductor laser device

AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha

InventorTadaaki Suda

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Abstract

A power controller controls a power of a laser emitted from a semiconductor laser device which includes a laser diode and an internal photodiode integrally assembled in a small substrate. The laser diode is electrically energized by an electric current power source, and the laser power is detected as a first electric current signal by the internal photodiode. An external photodiode detects the laser power as a second electric current signal. A feedback controller controls the power source on the basis of one of the first and second electric current signals. The controlling of the power source by the feedback controller is based on the second electric current signal when the operation of the external photodiode is proper and normal. The controlling of the power source by the feedback controller is based on the first electric current signal when the operation of the external photodiode is improper and abnormal.

Claims11

Dependent claims

A power controller for a semiconductor laser device including a laser diode and an internal photodiode integrally assembled in a small substrate, which comprises:

an electric current power source that electrically energizes said laser diode, an output power of said laser diode being detected as a first electric current detection signal by said internal photodiode;
an external photodiode that detects an output power of said laser diode as a second electric current detection signal;
a feedback controller that controls said electric current power source on the basis of one of said first and second electric current detection signals;
and
a determiner that determines whether an operation of said external photodiode is proper and normal,
wherein the controlling of said electric current power source by said feedback controller is based on said second electric current detection signal when it is determined by said determiner that the operation of said external photodiode is proper and normal, and
wherein the controlling of said electric current power source by said feedback controller is based on said first electric current detection signal when it is determined by said determiner that the operation of said external photodiode is improper and abnormal.

4 more elements

A power controller for a semiconductor laser device including a laser diode and an internal photodiode integrally assembled in a small substrate, which comprises:

an electric current power source that electrically energizes said laser diode, a output power of said laser diode being detected as a first electric current detection signal by said internal photodiode;
an external photodiode that detects an output power of said laser diode as a second electric current detection signal;
a feedback controller that controls said electric current power source on the basis of one of said first and second electric current detection signals;
a first determiner that determines whether an operation of said internal photodiode is proper and normal;
and
a second determiner that determines whether an operation of said external photodiode is proper and normal,
wherein the controlling of said electric current power source by said feedback controller is based on said second electric current detection signal when it is determined by said second determiner that the operation of said external photodiode is proper and normal, and
wherein the controlling of said electric current power source by said feedback controller is based on said first electric current detection signal when it is determined by said second determiner that the operation of said external photodiode is improper and abnormal and when it is determined by said first determiner that the operation of said internal photodiode is proper and normal.

5 more elements

Dependencies are inferred from the claim text.