Study On Integrated Photonic Microwave Arbitrary Waveform Generation With High Updating Rate

Microwave arbitrary waveform generation can find widespread applications in the fields such as high-speed communication,radar and electronic countermeasures.Compared with the traditional electronic methods,where microwave signals with high frequency and large bandwidths are difficult to generate due to the “electronic bottleneck”,photonic methods exhibit inherent advantages,and have become a focus of research.The silicon-on-insulator(SOI)-based photonic integration technique has attracted a lot of interest due to its small size,low weight,low power consumption,high stability as well as the compatibility with the CMOS technology.Focusing on the photonic integration-based microwave arbitrary waveform generation,we have done the following work.First,an integrated arbitrary waveform generation scheme with high updating rate was presented,which included a waveform switcher and multiple waveform generators.Different waveforms generated by the waveform generators were subsequently switched by the waveform switcher at a high speed.In our design,the electro-optic switch was chosen as the waveform switcher,and the microring-resonator based spectral shaper was chosen as the core of the waveform generator.Based on the analysis of the working principles,combining the transfer matrix method and the coupled mode theory,the two devices were designed.An electro-optic switch with a 7ns response time,and a tunable spectral shaper were obtained numerically.Based on the simulation of the system output,the microwave waveforms could be updated at a high speed.Second,an on-chip wavelength-to-time mapping scheme was presented based on the linearly chirped waveguide Bragg grating(LCWBG).The effects of the structural parameters on the Bragg wavelength,bandwidth,and the time delay were analyzed.Two LCWBGs were designed with different dispersions and apodization was employed to optimize the reflection spectra and the delay characteristics.The spiral LCWBG was further designed to minimize the effect of the waveguide thickness inhomogeneity.According to the simulation results,two microwave bursts were obtained using the presented LCWBGs,with frequencies of 37.8GHz and 54.4GHz,respectively.The use of the electro-optic switch was also suggested to enable the high updating rate of the presented on-chip SS-WTT.