Research On Optical Receiving Technology

Whispering Gallery Mode is the resonant mode field in cylindrical or spherical cavity. People realized its importance, because of its high-Q value, small mode volume and other characteristics. WGM finds its applications in a broad area from basic physics to optical communication among which the WGM cavity and microstrip line based technology for optical receiving is a recent breakthrough. In this dissertation, firstly we introduce the history, theory and applications of WGM resonator in detail. Then we discuss the experimental design and adjustment techniques of a prism coupled WGM resonator. The input and output of the light beam are realized by two collimators. We studied the change of optical spectrum under different gap sizes, incident angles, receiving positions and receiving angles. Especially we find that by changing the receiving position and receiving angle, not only the Q-value of the reflected spectrum is different, but also the resonant frequencies change accordingly, which means we find a new method to realize a tunable filter. This phenomenon is explained using couple mode theory together with high level WGM theory. Our study of WGM resonator is for the realization of a WGM resonator based optical receiver, therefore we also pay attention to some problems in the design of microstrip line for optical receiving technology. Based on the analysis of the work of predecessors, we proposed two optimization strategies in order to make sure there is only a half wavelength of pure standing wave of RF field on the WGM resonator: extend the mirostrip line outside the WGM resonator area, and shorten the part of the line on top of the WGM resonator.