New balance detection bias control method for MZ external modulator

Abstract

The invention discloses a new balance detection bias control method for an MZ external modulator. The method comprises the following steps: sending RF (radio frequency) signals and pilot signals into a signal end of the MZ external modulator after synthesizing the RF signals and the pilot signals by a signal synthesizer, wherein modulated light signals pass through an optical splitter and part of the optical signals enter an photoelectric detector; converting the part of the optical signals into electric signals by the photoelectric detector; detecting the electric signals; detecting fundamental waves and secondary harmonics of the pilot signals or two or more harmonic components; performing division operation on a transmission function of the two harmonic components and obtaining an adjustment amount of a direct current bias according to a ratio function after the division operation; and obtaining a bias voltage according to the adjustment amount of the direct current bias and sending the bias voltage into the direct current bias end of the MZ external modulator to realize the closed-loop control of an optimal direct current bias point of the MZ external modulator. By using the method, the influence on the precision of a direct current bias control method caused by the output power of a laser and the loss of a link can be eliminated, so that the precision of a system is improved.

Description

technical field [0001] The invention relates to an optical communication external modulation technology, in particular to a new balance detection bias control method of an MZ external modulator. Background technique [0002] Due to the explosive growth of the demand for information in the information age, especially driven by the Internet's demand for information in the whole society, optical communication is becoming more and more popular due to its characteristics of large bandwidth, high reliability, low cost, and strong anti-interference ability. Capacity direction has achieved rapid development. The rapid development of optical communication systems and optical networks has also brought a new revolution to the information age. Optical communication will gradually replace traditional switching, transmission, and access technologies, and eventually realize all-optical networking. [0003] The high-speed optical communication system is mainly composed of three parts: high...

AI Technical Summary

Problems solved by technology

[0015] 1. It is greatly affected by the fluctuation of the output optical power of the laser:

[0016] The disadvantage of the above method is that it has strict requirements on the stability of the output optical power of the laser

Because the second harmonic component of the pilot signal is very small when it is close to the optimal DC bias point, if the output optical power of the laser is unstable, the second harmonic component of the pilot signal is particularly affected by the change of the laser power. In serious cases, it will overwhelm the information reflecting the DC bias point of the modulator, thus greatly reducing the DC bias control accuracy of the modulator

Although measures can be taken to stabilize the light output of the laser source, it is expensive and inevitably has certain power fluctuations

This does not fundamentally solve the problem that the accuracy of the DC bias control method is affected by the change of the optical power of the laser

[0017] 2. Greatly affected by link loss:

[0020] Since only the magnitude of the second harmonic component is detected, there is only one value reflecting the DC bias voltage at a certain moment, thus limiting the algorithm that can be adopted by subsequent microprocessors

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