Microwave Receive And Transform Device Based On LiNbO₃ Microdisk

The technology including computer and communication networks has promoted the human society to the Information-Age, mobile communication has become as a widespread communication tool. As the bandwidth of the information transmission is highly demanded day by day, the frequency of the transmission carrier are also rising.This paper relate to a method to achieve the high-bandwidth high-frequency transmission by transfering the RF signal through fiber (ROF), which uses electro-optic modulation to achieve the conversion of microwave signals to optical signal. The core of the conversion is based on a very high Q electro-optic diskmodulator, which is made of LiNbO₃------a kind of electro-optic material with veryhigh conversion coefficient. Simultaneous resonance of the microwave stripline ring resonator and the whispering gallery disk optical resonator are used to achieve very high conversion resolution.The study of the high-resolution microwave converter can be divided into two big parts, including the part of microwave properties and the part of optical properties. In this paper, we gave the emphasis on the second part—optical properties of the converter. First of all, we theoretically analyse the incentive condition of the whispering gallery mode. After comparison and analysis of a variety of LiNbO₃ disk WGM coupling methods, we advanced a brand new scheme which use LiNbO₃ substrate waveguide to incent the WGM in the LiNbO₃ disk. Under this scheme, we can expediently made a M-Z modulator on the LiNbO₃ substrate to reduce the volume of the converters (We tried this scheme for a Nation Patent, Application NO. 200710066897.8). The M-Z modulator on the LiNbO₃ substrate can have both of its arms coupled to LiNbO₃ disk as a solution to the optical path difference compensation, which synchronously engender a Push-Pull structure. As a result, microwave modulation voltage can be debased and the converter symmetry can be improved. Based on this, we preliminarily built a platform for the verification experiments of the LiNbO₃ disk coupling with both prism and LiNbO₃ substrate waveguide, and observed some phenomena from the experiment. We successfully coupled the LiNbO₃ substrate waveguide optical signal to LiNbO₃ disk. Transmission loss before and after contact can be achieved around 4dB, which made a good foundation for the further study.