The Investigation Of Silicon Based Integrtaed Microwave Filters And Delaylines

Integrated microwave photonics combines the advantages of integrated photonics of small size,low power consumption,high reliability,and the advantages of microwave photonics of large bandwidth,and the immunity to electromagnetic interference.It has great potential to be applicated in the fields such as wireless communications,radar,and electronic warfare systems.Among various integrated microwave photonic devices,the integrated microwave photonic filters and integrated microwave photonic delay lines are two vital devices,which are widely used to process microwave signals within optical domain and to realize the optical beamforming.For integrated microwave photonic filters,improving their radio frequency rejection ratio,realizing fine filtering,and flexible and reconfigurable filter spectra are the focus and difficulty of research.Whereas,for the integrated microwave photonic delay lines,they are required to have high tuning precisions,wide tuning ranges,high operating frequencies,and large operating bandwidths.In this dissertation,a series of innovative structures and schemes have been proposed focus on the integrated microwave photonic filters and delay lines,and those difficulties and requirements have been studied theoretically and experimentally.The main studies of this dissertation are summarized as below:1.Based on the silicon-on-insulator platform,some basic integrated photonic components,such as variable optical attenuator,multimode interference coupler,optical switch,microring resonator,etc.have been designed.Based on the self-coupling microrings assisted MZI structure,a multifunctional,flexibly reconfigurable integrated photonic filter is innovatively proposed and fabricated.The device can be reconstructed into five kinds of integrated photonic filters with different functions,which can be applied to the fields of microwave photon filters,optoelectronic oscillators,microwave photon frequency measurement,etc.,and has good application prospects.2.An integrated microwave photonic filter based on unbalanced optical double-sideband modulation is proposed to achieve a large rejection ratio and a large frequency tuning range.Making use of the RF cancellation technology,a rejection ratio exceeding 55 d B has been achieved experimentally.The filter's frequency can be tuned from 2.5GHz to 18.75 GHz,and the filtering bandwidth can be tuned from 0.65 GHz to 2.2GHz.Moreover,the spectrum of the filter can be switched from bandpass response to bandstop response.A theoretical analysis on the different performances of the filter with over-coupled microring resonator and under-coupled microring resonator has been performed.The proposed scheme provides a new idea for the design of integrated microwave photonic filters.3.A microwave photonic filter based on a tunable optical frequency comb is proposed.By controlling the frequency interval and relative intensity of each comb lines,the filter's spectrum of the microwave photonic filter can be reconfigured.We have experimentally realized a RF rejection ratio of more than 60 d B,a bandwidth tuning range of 1.16 GHz to 13.3GHz,and a small stopband fluctuation smaller than 0.56 d B.It provides a new direction for the design of reconfigurable integrated microwave photonic filters.4.To meet the requirements of the 40 GHz one dimensional optical beamforming network,a single-channel 7bit optical tunable delay line chip has been designed.In the experiment,a high delay time tuning precision of 1.52 ps is realized.Then,a four-channel optical beamforming network chip based on 5bit optical tunable delay lines has been designed for the 1×4 40 GHz optical beamforming network.It is desired to achieve a ±45° beam steering angle,which covers 7 discrete beam steering directions.The power consumption of each delay channel is about 200 m W.The insertion loss and delay time increment are 10.1d B and 3.02 ps,respectively.The results showed that the four channels of delay lines on the chip have good uniformity.Based on the measured delay times,the directional diagram has been simulated,and the result shows that the maximum deviation between the designed and the simulated radiation angle is about 3.24°.The results proved the validity of the chip.5.Finally,for a 4×4 two-dimensional phased antenna array,the optical beamforming network based on wavelength division multiplexing and the optical beamforming network based on16-channel optically tunable delay line with a delay increment of 2.083 ps have been analyzed.The16-channel optical beamforming network chip has been designed and taped out,laying the foundation for further research on the two-dimensional optical controlled phased antenna arrays.