Control circuitry in optoelectronic modules for laser crossing point adjustment

Abstract

A laser and a monitor photodiode providing a monitor signal. Laser driver circuitry has a data input terminal, a laser bias output terminal, a laser modulation output terminal, and a bias control input terminal. A processor having a bias control output terminal coupled to the bias control input terminal through an adjustable resistance for controlling the monitor signal from the photodiode, a modulation control output terminal coupled to a modulation setting input terminal through an adjustable resistance for controlling amplitude of modulation of the laser, and a modulation crossing point control output terminal coupled to a power adjustment input terminal of the laser driver circuitry through an adjustable resistance for adjusting modulation of the laser to achieve a desired crossing point in the optical output.

Description

technical field [0001] The present invention relates to optoelectronic modules, and more particularly to the cooperation between lasers and power monitoring photodiode circuits in optical communication systems. Background technique [0002] In optoelectronic modules for various communication fields, one of the most difficult problems that must be solved is the efficient transmission of light between the light generating device and the optical fiber. It should be understood by those skilled in the art herein that the term "light" is a general term that includes any electromagnetic radiation capable of being modulated and transmitted through an optical fiber or other optical transmission line. [0003] Typically, the optical power of a semiconductor laser is monitored and used in a feedback loop to control the laser to ensure constant output from individual devices and to ensure standard output between similar devices. Throughout this disclosure, lasers are used as the primar...

AI Technical Summary

Problems solved by technology

The problem that arises is that the laser turn-on and turn-off times may not be the same and the crossing point between the operation of the laser and the photodiode drive loop may be skewed or shifted from the nominal crossing point to a higher or lower crossing point, thereby Changing the eye quality

Also, temperature can affect laser turn-on and turn-off times or other operating characteristics, thereby changing eye pattern quality

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