Control system and method of bias voltage of IQ optical modulator

Abstract

The invention discloses a control system of bias voltage of an IQ optical modulator and a control method of the bias voltage of the IQ optical modulator. The control system comprises a laser optical source, a polarization controller, the IQ optical modulator, an optical coupler, a photoelectric detector and a data processing module, which are connected in sequence, wherein the output of the IP optical modulator is divided by the optical coupler, and then is connected to the photoelectric detector; the output of the IP optical modulator is connected with the input of the data processing module; three outputs of the data processing module are respectively sent to the direct current bias voltage input ports of three subsidiary modulators of the IQ optical modulator. The control method comprises the steps of optimizing the bias voltage of a subsidiary phase modulator by measuring the maximum value and the adjacent minimum value of an output optical power, loading the minimum value of search optical power of a path of low-frequency square signal onto two subsidiary intensity modulators in sequence to optimize the bias voltages of the two subsidiary intensity modulators on that basis, and finally realizing the control and locking on each subsidiary modulator working point of the IQ optical modulator. By applying the control system and the control method, the perfect bias point of the IQ optical modulator can be rapidly and automatically controlled.

Description

technical field [0001] The invention belongs to the technical field of optical fiber communication, and more specifically relates to a system and method for controlling a bias voltage of an IQ optical modulator. Background technique [0002] With the widespread development of large-bandwidth services such as mobile Internet, cloud computing, 3D TV, high-definition video on demand, telemedicine, and virtual reality, as well as the continuous expansion of the number and scope of broadband network access users, long-distance networks as the backbone of modern communication networks The transmission capacity of the optical fiber communication network will still face huge growth pressure, and put forward higher requirements for the optical transmission system from the network to the device. Coherent optical communication can provide higher receiving sensitivity, apply various high-order modulation patterns, and use digital signal processing (DSP) to balance various optical domain...

AI Technical Summary

Problems solved by technology

[0005] At present, there have been many studies on the control method of modulator bias voltage, such as adding sinusoidal disturbance signals of different frequencies to the DC bias input of each modulator, performing spectrum analysis at the receiving end, and extracting multiple frequencies The relevant data processing operation is carried out to obtain the control information of each bias point. This method needs to generate multiple sinusoidal disturbance signals of different frequencies at the same time, and also needs to do more complex data processing operations, which requires high hardware. At the same time The calculation delay is large, and its practical scope of application is limited

While other reported IQ optical modulator bias point control methods such as methods based on monitoring the back optical power, methods based on differential phase monitoring, they need to add additional lasers, need to monitor complex constellation diagrams, or require lock-in amplifiers , which not only increases system complexity and cost, but also may interfere with other wavelength channels

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