Nonlinearity correction method for external cavity tunable semiconductor laser based on FPGA

Abstract

The invention discloses a nonlinearity correction method for an external cavity tunable semiconductor laser based on FPGA. The method realizes DA output of a PZT driving signal based on FPGA and drives sweeping motion of a flexible hinge, the FPGA samples a PZT displacement signal through an AD module and analyzes by algorithm to obtain a displacement nonlinearity error, the error signal feedbacksuperimposes the initial signal to obtain a new driving signal, and such cycle is repeated until the PZT piezoelectric ceramic nonlinearity is eliminated. The nonlinearity correction method provided by the invention realizes data real-time acquisition through the AD module based on the FPGA control system, real-time processes and analyzes the collected signal through the FPGA controller to obtaina real-time system error signal, and loads the error signal as a feedback amount into the driving signal to make real-time correction to the control signal. Therefore, the system provided by the invention replaces the traditional offline acquisition and analysis system, can realize real-time closed-loop correction control, and has high system precision and good control effect.

Description

technical field [0001] The invention belongs to the technical field of semiconductor lasers, and in particular relates to a non-linear correction method of an external cavity tunable semiconductor laser based on FPGA. Background technique [0002] The PZT nonlinearity of FPGA-based external cavity tunable semiconductor laser means that the change of optical frequency in the same time interval is not a constant value. The reasons for this nonlinear phenomenon are the hysteresis characteristics of PZT piezoelectric ceramics, temperature drift, nonlinearity of the inner cavity and other factors, and the hysteresis characteristics of PZT piezoelectric ceramics are the nonlinearity of the optical frequency output of the external cavity tunable semiconductor laser. the main reason. The hysteresis characteristic of PZT piezoelectric ceramics refers to the nonlinear relationship between the input voltage and output displacement of piezoelectric ceramics. [0003] At present, the r...

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Problems solved by technology

[0012] These control methods do not require an inverse model, do not require complex calculations, and some do not even need to consider the object model, such as neural network and sliding mode variable structure control methods, but these control methods also have the problem of local optimal solutions, resulting in inconsistencies in the system. Stable, adaptive control method is prone to misoperation, and the control accuracy of digital PID is not as good as that based on hysteresis inverse model control system

In short, there are certain problems in the actual use of the methods based on the above-mentioned various models, especially the use of the above-mentioned schemes in the laser nonlinear correction system is too complicated and redundant, and some control schemes need to be implemented offline, which does not conform to the actual system Usage

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