Semiconductor laser optical output control circuit and optical device

A semiconductor laser optical output control circuit for controlling an optical output of a semiconductor laser to a desired intensity in accordance with a supplied drive current, comprising:

• an optical output detecting means for detecting the optical output of said semiconductor laser;
• a first detecting means for detecting a first level of said optical output detected by said optical output detecting means;
• a second detecting means for detecting a second level of said optical output detected by said optical output detecting means;
• a third detecting means for detecting a third level intermediate between said first level and second level of said optical outputs detected by said optical output detecting means;
• a first optical output setting means for giving a first setting value of a first level in the optical output of said semiconductor laser;
• a second optical output setting means for giving a second setting value of a second level in the optical output of said semiconductor laser;
• at least one third optical output setting means for giving a third setting value of a third level in the optical output of said semiconductor laser;
• a first switching means for switching and outputting the first, second, and third setting value signals of said optical outputs given by said first, second, and third optical output setting means;
• a fourth detecting means for detecting the first setting signal among the outputs of said optical output setting switching means;
• a fifth detecting means for detecting the second setting signal among the outputs of said optical output setting switching means;
• at least a sixth detecting means for detecting the third setting value signal among the outputs of said optical output setting switching means;
• a first comparing means for comparing the detected output of said first detecting means with the detected output of said fourth detecting means and outputting the comparison result;
• a second comparing means for comparing the detected output of said second detecting means with the detected output of said fifth detecting means and outputting the comparison result;
• at least one third comparing means for comparing the detected output of said third detecting means with the detected output of said sixth detecting means and outputting the comparison result;
• a second switching means for switching and outputting the comparison results of said first, second, and third comparing means in synchronization with the switching by said first switching means;
• and
• a current supplying means for supplying said drive current in accordance with the output signal of said second switching means to said semiconductor laser.

An optical device comprising a semiconductor laser optical output control circuit for controlling an optical output of the semiconductor laser emitted to an optical medium to a desired intensity in accordance with a supplied drive current, wherein:

• said semiconductor laser optical output control circuit comprises:
• an optical output detecting means for detecting the optical output of said semiconductor laser;
• a first detecting means for detecting a first level of said optical output detected by said optical output detecting means;
• a second detecting means for detecting a second level of said optical output detected by said optical output detecting means;
• a first optical output setting means for giving a first setting value of a first level in the optical output of said semiconductor laser;
• a second optical output setting means for giving a second setting value of a second level in the optical output of said semiconductor laser;
• a first switching means for switching and outputting first and second setting value signals of said optical output given by said first and second optical output setting means;
• a third detecting means for detecting the first setting value signal among outputs of said optical output setting switching means;
• a fourth detecting means for detecting the second setting value signal among the outputs of said optical output setting switching means;
• a first comparing means for comparing the detected output of said first detecting means with the detected output of said third detecting means and outputting the comparison result;
• a second comparing means for comparing the detected output of said second detecting means with the detected output of said fourth detecting means and outputting the comparison result;
• a second switching means for switching and outputting the comparison results of said first and second comparing means in synchronization with the switching by said first switching means;
• and
• a current supplying means for supplying said drive current in accordance with the output signal of said second switching means to said semiconductor laser.

An optical device comprising a semiconductor laser optical output control circuit for controlling an optical output of a semiconductor laser emitted to an optical medium to a desired intensity in accordance with a supplied drive current, wherein:

• said semiconductor laser optical output control circuit comprises:
• an optical output detecting means for detecting the optical output of said semiconductor laser;
• a first detecting means for detecting a first level of said optical output detected by said optical output detecting means;
• a second detecting means for detecting a second level of said optical output detected by said optical output detecting means;
• a third detecting means for detecting a third level intermediate between said first level and second level of said optical outputs detected by said optical output detecting means;
• a first optical output setting means for giving a first setting value of a first level in the optical output of said semiconductor laser;
• a second optical output setting means for giving a second setting value of a second level in the optical output of said semiconductor laser;
• at least one third optical output setting means for giving a third setting value of a third level in the optical output of said semiconductor laser;
• a first switching means for switching and outputting the first, second, and third setting value signals of said optical outputs given by said first, second, and third optical output setting means;
• a fourth detecting means for detecting the first setting value signal among the outputs of said optical output setting switching means;
• a fifth detecting means for detecting the second setting value signal among the outputs of said optical output setting switching means;
• at least a sixth detecting means for detecting the third setting value signal among the outputs of said optical output setting switching means;
• a first comparing means for comparing the detected output of said first wave detecting mean with the detected output of said fourth detecting means and outputting the comparison result;
• a second comparing means for comparing the detected output of said second detecting means with the detected output of said fifth detecting means and outputting the comparison result;
• at least one third comparing means for comparing the detected output of said third detecting means with the detected output of said sixth detecting means and outputting the comparison result;
• a second switching means for switching and outputting the comparison results of said first, second, and third comparing means in synchronization with the switching by said first switching means;
• and
• a current supplying means for supplying said drive current in accordance with the output signal of said second switching means to said semiconductor laser.