Bias Control Method of Electro-optic Modulator Based on Sagnac Loop

Abstract

The invention discloses a system device and method for controlling the bias voltage of an electro-optical modulator, provides an automatic bias control system based on a Sagnac ring and a direct-current power detecting algorithm and mainly relates to the field of the optical communication technology and automatic control. According to the system device and method for controlling the bias voltage of the electro-optical modulator, an optical carrier is split into two paths at the output end of a light source with a polarization controller and a polarization beam splitter and enters the Sagnac ring, wherein the clockwise optical carrier is subjected to intensity modulation, while the anticlockwise optical carrier is not modulated with radio-frequency signals due to the reverse modulation characteristic of the electro-optical modulator; optical signals output by the Sagnac ring pass through the polarization controller and the polarization beam splitter so as to make the unmodulated optical signals enter a bias control module through a photoelectric detector, judgment and compensation can be carried out on direct-current drifting with a direct-current power detection method, and thus a direct-current working point of the modulator is locked. According to the scheme, the defect that the direct-current power detection method is affected by radiofrequency signals is overcome with the Sagnac ring, and automatic bias control irrelevant to the radiofrequency signals is achieved.

Description

technical field [0001] The invention relates to the fields of optical communication technology and digital signal processing technology, in particular to a method for realizing bias voltage control of a Mach-Zehnder modulator (MZM) based on a Sagnac ring. Background technique [0002] Radio frequency communication over fiber (RoF) technology utilizes the respective advantages of optical fiber and high-frequency radio waves to realize low-cost, large-capacity RF signal optical fiber transmission and wireless access, which is an inevitable trend in the future development of broadband access. As the core device of the RoF system, the MZM based on lithium niobate material is widely used in the field of optical communication because of its advantages of large modulation bandwidth, low loss, and zero chirp. Its performance plays a decisive role in the signal transmission quality of the entire system. . [0003] Due to the limitations of modulation materials and structures, factor...

AI Technical Summary

Problems solved by technology

But the shortcomings are also obvious. The most important thing is that the DC component is affected by the RF signal, especially when it works near the minimum operating point. When the RF signal changes, the DC component will change significantly, which will affect the judgment and detection of the bias voltage.

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