Bias working point automatic control system based on temperature drift compensation

Abstract

The invention discloses a bias working point automatic control system based on temperature drift compensation. A method comprises the steps: monitoring and recording the output optical power of the modulator through a feedback loop module; calculating the ratio of the output optical power to the maximum output optical power to serve as the measurement value of a bias working point at the initial temperature and monitoring the fundamental wave and second harmonic components of a pilot signal; performing calculating to obtain a modulator bias phase coefficient and a phase coefficient corresponding to each power ratio, taking the phase coefficient at the moment as a direct-current bias phase coefficient standard value, completing initialization work of a modulator bias working point, and closing the pilot signal; enabling the temperature monitoring module to detect the real-time temperature of the modulator, and sending a control signal to the feedback loop module when the temperature changes; enabling the feedback loop module to receive the control signal, starting a pilot method to correct the working point, and continuously adjusting the bias voltage until the standard value driftsclose to zero, so the stability of any bias working point is realized, and the influence of temperature change is basically avoided.

Description

technical field [0001] The invention relates to the technical field of modulator control, in particular to an automatic control system of a bias operating point based on temperature drift compensation. Background technique [0002] Microwave photonic links have important applications in radar systems, radio frequency optical fiber transmission, microwave signal generation, optical fiber sensing and other fields. Among them, radio frequency optical fiber transmission (ROF) is a method that modulates radio frequency signals to optical carriers and transmits them using optical fibers. Compared with coaxial cable transmission, ROF has the advantages of light weight, low loss, high speed and large capacity. A basic ROF link based on an external modulator is composed of a laser, an external modulator, and a photodetector. The external modulator is an important device for realizing electro-optic conversion, compared to directly loading a radio frequency signal to a laser to achieve...

AI Technical Summary

Problems solved by technology

However, in practical engineering applications, the operating point of the Mach-Zehnder modulator is easily affected by environmental changes, such as temperature, pressure, and mechanical vibration, which will cause the shift of the operating point of the modulator, resulting in the deterioration of link performance.

The existing methods for stabilizing the MZM operating point mainly include the pilot method and the optical power control method, but the pilot method cannot achieve the stability of any operating point and the pilot will cause intermodulation near the carrier, which will affect the phase purity of the signal

The optical power control method is affected by temperature changes, and the control accuracy is not high, so the existing two methods are difficult to meet the stable requirements of high-precision arbitrary bias operating points

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