Study On The LNOI Optical Waveguide Rf Receiver

In the context of global information interconnection,with the rise of new applications,people’s demand for information transmission with high speed,low delay and low loss is increasing day by day.However,the traditional information transmission method based on metal coaxial cable shows obvious weaknesses in the microwave and millimeter wave bands,including high loss,large delay,limited bandwidth,serious attenuation,and so on.Optical information transmission based on optical fiber radio(ROF)system can overcome the above shortcomings,and has become the first choice for high-speed,high-bandwidth and low-loss information transmission.Even so,in view of the flexibility and convenience of wireless communication,RF signal reception still plays an important role in communication systems.However,there are some limitations in the cost and loss of RF signal receiving devices currently used.Whereas the RF signal receiver which can combine the signal receiving antenna with electro-optic modulator can not only reduce the cost,but also reduce the size of the receiving system,so it has gradually attracted people’s attention.In this dissertation,based on x cut y propagation thin film lithium niobate platform,RF signal receiver combining asymmetric MachZehnder interferometer(MZI)optical waveguide modulator and integrated microstrip patch antenna is studied.The main work of this paper is as follows:Firstly,the advantages of using optical signal to transmit information over using electrical one are described.And the significance of the RF signal receiver which can directly modulate the RF signal onto the optical carrier and combining the antenna with optical waveguide modulator on the same chip is discussed.The development history and practical application scenarios of the related devices are introduced.Secondly,the basic structure of thin film lithium niobate optical waveguide RF signal receiver is introduced.And the relevant theoretical knowledge involved in the device is analyzed and discussed,including the theory of optical waveguide,the analysis of ridge waveguide by the effective refractive index method,the electro-optical effect of lithium niobate crystal,and the working principle and transmission characteristics of thin film lithium niobate optical waveguide RF signal receiver.Thirdly,the key structures of the asymmetric MZI optical waveguide used in the RF signal receiver are designed by using Rsoft CAD software,including the phase shift arm and the multi-mode interference(MMI)coupler used for splitting light,and the performance and fabrication tolerance of the designed MMI are discussed.A microstrip patch antenna suitable for integrated optical waveguide modulator is designed by using HFSS software.The influence of structural parameters of microstrip antenna on its performance is discussed.Then,the microstrip patch antennas operating at 20 GHz and10.5 GHz are designed respectively.Finally,the fabrication method and process of the proposed device are introduced,and the test for the fabricated device is carried out,including the insertion loss test and the modulation performance test.The test results show that the insertion loss of the device is about 16.0 d B and the extinction ratio is about 11.1 d B when the working wavelength is 1550 nm.The half-wave voltage of the device is about 20.6V and the half-wave voltage length product is 10.3V·cm.