Research Of Optical Arbitrary Waveform Generator Based On XPM

Optical arbitrary waveform generator(OAWG)synthesizes optical pulses with high speed and broad bandwidth.Waveform,delay,width and repetition of the generated pulse can be flexibly changed by using OAWG,which could find applications in numerous fields,such as coherent control over quantum mechanicalprocesses,the generation of attosecond pulses,the generation and transformation of various complex patterns in communication systems,and photonically enabled generation and processing of ultrabroadband radiofrequency signals.In this paper,two OAWGs based on cross phase modulation(XPM)are proposed.The main novelties compared with previous OAWG are listed as follows: the spectrum is separated by arrayed waveguide grating(AWG).The amplitude and phase of each line is changed by the control light power according to the theory of XPM.And then the required arbitrary waveform is synthesized consequently.The generated waveform can be dynamically updated when the control light power is dynamically changed.In this structure,the adjustment of each line is independent and the operation is simple and flexible.The AWG has relatively small loss,high stability and is easy to integration.Furthermore,the XPM effect has ultrafast response rate,which can be used to update the waveform dynamically.The main work in this thesis includes the following parts:An OAWG based on XPM is proposed.The input optical frequency comb is separated by AWG.The amplitude and phase of each line is changed by the control light power according to the theory of XPM.And then the required arbitrary waveform is synthesized consequently.The generated waveform can be dynamically updated when the control light power is dynamically changed.Both of static and dynamic waveforms are synthesized by simulation and the factors that affect the system performance are analyzed.In order to reduce control light power and simplify system structure,an OAWG based on nonlinear ring resonator(NRR)is proposed.According to the characteristics of XPM,the phase of each line can be changed along with control light power in NRR.Therefore,the amplitude and phase of each line can be controlled by two variable optical attenuator(VOA)arrays.The phase adjustment of NRR is verified and various waveforms are synthesized by experiment and simulation.In order to increase the amount of spectral lines,the spectrum of femtosecond laser is used to generate optical frequency comb and the OAWG based on XPM is verified experimentally.40 spectral lines are adjusted independently and various waveforms with high fidelity are generated by experiment and simulation.