The Research On Arbitrary Waveform Generator Based On Microwave Photonics

Microwave photonics(MWP)theory and technology have been widely used in civil defense applications.In recent years,the microwave waveform signal generated based on photonic technique has become a very attractive research field.Nowadays the generation of triangle waves,square wave and sawtooth wave are widely used in various fields,such as all-optical signal processing systems,wire communication system,radars and sensors.So far,various solutions for generating arbitrary waveform signals have been proposed,but there are problems in many aspects.For example,the arbitrary waveforms generated by traditional electrical technology have shortcomings of low bandwidth and high noise.When electronic equipment is introduced to solve the above-mentioned problems,not only the application range is limited,but also the design cost is increased.At present,using MWP technology to generate arbitrary waveforms is a research hotspot for people from all over the world.The MWP arbitrary waveform system can not only solve the problems in electrical solutions,but also greatly enhance the quality factor and angular resolution of the generated waveform.Therefore,it is very important to propose a complete arbitrary waveform generator system.This paper describes the principle of MWP arbitrary waveform generators,and summarized the methods of the present arbitrary waveform generation.The development status of arbitrary waveform generators at home and abroad is introduced.In the meantime,the advantages and disadvantages of several schemes are briefly compared,and the important components mentioned in the generator system are briefly introduced,focusing on the principle part and usage method.At the same time,this article elaborates on the principle of stimulated Brillouin scattering employed in our schemes.In this article,an arbitrary waveform generator based on the principle of stimulated Brillouin scattering is presented.By setting the bias voltage of the Mach-Zehnder modulator reasonably,even harmonic suppression can be achieved.After theoretical analysis,the value of Brillouin frequency shift used to recover the carrier can be obtained,and the wavelength of the laser can be determined.Eventually,the triangle wave,square wave and sawtooth waveform can be successfully generated.In this paper,a research scheme of arbitrary waveform generator based on Sagnac ring is proposed.A continuous wave is sent from the tunable laser source to the Sagnac ring.Based on the principle of speed adaptation,the optical signal is modulated in clockwise and counterclockwise direction.Consequently,the carrier and the two-sided third-order sideband can be obtained.Then the first-order sideband in the lower branch is used as the pump light to attenuate the one-sided sidebands.Finally,a triangular wave,a square wave and a sawtooth wave are obtained.According to actual condition,the simulation experiment proves the feasibility of the experiment.It is certain that the stability of the arbitrary waveform system is improved when the repetition frequency is tunable.