Working point control device and working point control method applied in MZ (Mach-Zehnder) modulator

Abstract

The invention discloses a working point control device and a working point control method applied in an MZ (Mach-Zehnder) modulator. The working point control device comprises a light modulator, a transimpedance amplifier, a low noise amplifier, a high-Q bandpass filter, a first level conditioner, a microprocessor and a second level conditioner, wherein the transimpedance amplifier is used for converting current output from PD (potential difference) of the modulator into a voltage signal; the low noise amplifier is used for detecting a low frequency signal and amplifying the low frequency signal so as to increase the signal to noise ratio of a system; the high-Q bandpass filter is used for detecting an error signal and amplifying the error signal so as to increase the signal to noise ratio; the first level conditioner is used for conditioning the level of the error signal of a phase position, so that the signal output can meet the input range of the A / D (alternative current / direct current); the microprocessor is used for generating a low-frequency signal, and accomplishing the software synchronous wave detection and the proportional-integral PI conditioning algorithm; and the a second level conditioner is used for accomplishing the D / A (direct current / alternative current) output voltage conditioning, so that the D / A output can meet the voltage range of the direct current offset full control range of the optical modulator. By applying the invention, the problems that in the existing MZ modulator, the hardware control circuit at an offset point is more complex, and the control precision is not high can be solved.

Description

technical field [0001] The invention relates to optical transmission network technology, in particular to a working point control device and method applied to a Mach-Zehnder (MZ) modulator. Background technique [0002] In high-speed and long-distance communication transmission, it is difficult to meet the requirements by using intensity modulation. At present, in the long-distance transmission in the field of optical fiber communication, phase modulation technology needs to be used. The current photoelectric phase modulation is generally realized by using a Mach-Zehnder (MZ) electro-optic modulator (may be referred to as “MZ modulator” for short). However, the heat generated by the MZ modulator during operation, ambient temperature changes, and long-term aging will affect the strength of the electric field and easily change the characteristics of the electro-optic modulator, so that the ideal control point of the modulator will drift from the preset point. . The result ...

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Problems solved by technology

[0004] In view of this, the main purpose of the present invention is to provide a working point control device and method applied to the MZ modulator, to solve the problem that the hardware control circuit of the bias point of the existing MZ modulator is relatively complicated and the control accuracy is not high

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