Semiconductor laser light output stabilizing circuit and light transmitting module

Abstract

To stabilize extinction ratio of laser output light over the whole operating temperature range by suppressing the extinction ratio of laser output light from being increased more than required, by restraining an excess pulse drive current from flowing due to the saturation of the slope efficiency in an I-L characteristic in high temperature operation of a semiconductor laser. In an optical output stabilizing circuit in which a modulation current is controlled by detecting the slope efficiency in an injection current versus an optical output characteristic of the semiconductor laser 12, a temperature-compensation circuit 13 for a reference voltage of a difference amplifier 9 is added to reduce fluctuation of the extinction ratio of laser output light in high temperature operation by compensating the saturation of the slope efficiency by temperature-compensating the reference voltage in an error amplifier.

Description

technical field [0001] The present invention relates to an optical output stabilizing circuit and an optical transmission module of a semiconductor laser, in particular to a circuit that can stabilize the extinction ratio of the laser output light without using a Peltier element or the like to stabilize the temperature of the semiconductor laser, such as for use in assembly In optical transmitters using semiconductor lasers in optical fiber transmission devices. Background technique [0002] In order to stabilize the extinction ratio of the output light of the semiconductor laser, the semiconductor laser is sometimes subjected to temperature stabilization treatment using a Peltier element or the like, but in order to reduce power consumption and cost, the temperature stabilization treatment is also sometimes not performed. [0003] In this way, without temperature stabilization, conventional optical output stabilization circuits used to optimally control the bias current and...

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Problems solved by technology

[0023] In this way, there is a problem that on the high temperature side, the extinction ratio increases beyond the necessary value, and the emission line width of LD12 increases, resulting in deterioration of the dispersion compensation characteristic (which occurs when the optical signal obtained from LD12 is actually transmitted for several tens of kilometers with an optical fiber. resulting in reduced receiver sensitivity)

[0032] As mentioned above, there is a problem in the optical output stabilization circuit of the semiconductor laser in the past: when the semiconductor laser is high temperature, due to the saturation of the I-L characteristic, there is an excess pulse driving current, and the extinction ratio increases to more than the necessary value at high temperature.

[0033] In addition, the pilot signal detector in the optical output stabilization circuit of the conventional semiconductor laser has the problem that the amplitude of the pilot component must be increased beyond a certain level, resulting in the deterioration of the S / N of the emitted light and the reduction of the receiving sensitivity.

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