Bias voltage control method based on double parallel Mach-Zehnder modulator

Abstract

The invention discloses a bias control method based on a double-parallel Mach-Zehnder modulator, and relates to the field of microwave photonics, optical fiber sensing or optical communication. According to the invention, low-frequency disturbance voltage with a fixed frequency is applied to three bias voltage control ends of the DPMZM; a modulator output signal is fed back to a bias control module by selecting a certain proportion, and after the signal is processed by hardware circuits such as photoelectric conversion, filtering, amplification, sampling and the like, the bias point voltage ofa branch corresponding to the DPMZM is calculated by a bias point control algorithm in the MCU. The bias point voltage and different-frequency disturbance signals of which the three fundamental wavesand the second harmonic waves are not overlapped are superposed and input to a DPMZM bias voltage control port. The three control ports use disturbance voltages with different frequencies, so that feedback information of the control ports is separated in a frequency domain, independent closed-loop control of the three control ports is realized, voltages of three bias points of the DPMZM are adjusted at the same time, and stable control of the DPMZM on any bias point is realized.

Description

technical field [0001] The invention relates to the fields of microwave photon technology, optical fiber sensing technology and optical communication technology, in particular to a bias voltage control method based on a dual parallel Mach-Zehnder modulator. Background technique [0002] The Mach-Zehnder modulator is made of LiNbO 3 (Lithium niobate) material, LiNbO3 material is easily affected by factors such as the temperature of the environment, the optical power of the input device, and the aging of the device itself, which also affects the stability of the modulator and causes the bias point of the modulator to occur. Drift, the waveform of the output signal is also affected, so the control of the automatic bias point can ensure the stable function of the modulator. [0003] Single sideband modulation is a unique modulation method of DPMZM. Through microwave modulation of the incident laser light, the working point is adjusted to suppress the optical frequency component...

AI Technical Summary

Problems solved by technology

[0004] At present, there is a time-sharing cycle control method, which is divided into three time slots, and the bias points of the upper and lower arms and the main arm are controlled in turn. However, in the time-sharing control method, it is first necessary to stabilize the working point of the main arm, and then stabilize the upper and lower arms. The working point of the arm, so in the process of stabilizing the upper and lower arms, the working point of the main arm will drift again, so the accurate stable working point cannot be achieved, especially in the control of the working state of any point of the modulator

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