Realization system and method of optical phase-locked loop based on acousto-optic frequency shifter

Abstract

The invention provides an optical phase-locked loop implementation method based on an acousto-optical frequency shifter. According to the optical phase-locked loop implementation method, local oscillator laser devices, the acousto-optical frequency shifter, a balanced receiver and a phase frequency detector are included; output of each local oscillator laser device is modulated through the acousto-optical frequency shifter and then is divided into two output ends through a first polarization-maintaining optical fiber coupler, the first output ends and a signal light carrier wave pass through a second polarization-maintaining optical fiber coupler together and then are received by the balanced receiver, and output of the balanced receiver is connected to the phase frequency detector and a local reference signal to carry out phase discrimination; output of the phase frequency detector is divided into two output ends after passing through a loop filter, and the two output ends are used for driving the local oscillator laser devices and the acousto-optical frequency shifter respectively. The invention further provides an optical phase-locked loop implementation system of the optical phase-locked loop implementation method. According to the optical phase-locked loop implementation system and method based on the acousto-optical frequency shifter, phase changes of the two laser devices are compensated for through the frequency modulation characteristic of the acousto-optical frequency shifter, the phase coherence of the laser device with the narrow line width is transmitted to the laser device with the wide line width, heterodyne optical phase locking between the two laser devices is realized, and the line width of the laser device with the wide line width is reduced.

Description

technical field [0001] The invention relates to the field of laser technology, in particular to an implementation system and method for an optical phase-locked loop based on an acousto-optic frequency shifter. Background technique [0002] With the increasing demands of the information society for the bandwidth of optical fiber networks, the traditional optical communication technology based on intensity modulation / direct detection has gradually encountered bottlenecks due to its technical limitations, while the digital optical communication technology based on high-order modulation formats utilizes the phase of the optical carrier , frequency information for data transmission, which can obtain higher spectrum bandwidth utilization. High-order modulation formats such as Quadrature Amplitude Modularion (QAM) and Quadrature Phase ShiftKeying (QPSK) can greatly increase the symbol rate and increase the transmission capacity of existing optical fibers. Since the detection metho...

AI Technical Summary

Problems solved by technology

However, the harmonic components introduced by the modulation process will reduce the signal-to-noise ratio and spurious-free dynamic range, thereby affecting the sensitivity and dynamic range of the receiver, increasing the power cost of the system, and limiting its application in high-speed high-order modulation systems. performance

At the same time, since the frequency of the external modulation can only be the same as the baseband frequency of the modulation signal on the carrier, it greatly limits its application in microwave photonics and other related fields.

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