Optical Coupling In Microwave Photonic Receiving

With the growing demand for optical communication, the ROF technology has been widely studied and used. The paper is mainly concerning on microwave photonic receiving technology. This new receiver is based on an electro-optic modulator which is a Lithium Niobate micro-cavity integrated with electrodes or antenna structure. Compared to conventional millimeter-wave receiver, this new receiver owns a large number of advantages:small size, light weight, simple structure, low power consumption and high sensitivity. The receiver can achieve portable wireless communication if used in the ROF system.Whispering gallery modes(WGM) are the electromagnetic field oscillations in the resonant cavity formed by the resonant field, due to inbuilt a very high Q value and small size, it has drew a lot of attentions and has been widely researched in recent years. This paper mainly studied optical coupling part in microwave photonic receiver based on WGM micro-cavity, by using a swept light source, the evanescent coupling from the rutile prism into Lithium Niobate micro-cavity is successfully realized, the output spectrum is obtained.In this thesis, the WGM is analyzed and simulated theoretically, and the principle of the Lithium Niobate micro-cavity electro-optic modulator is introduced. Two kinds of laser sources were used for optical coupling experiment, one was DFB swept laser source and the other was a swept laser driven by circuit designed and made by ourselves. Using these two lasers to implement the optical coupling experiment, we both successfully realized the evanescent coupling from the rutile prism into Lithium Niobate micro-cavity. The coupled output spectrum clearly reflects the FSR of the Lithium Niobate micro-cavity when using DFB swept source, and it has a very high Q value.Finally, a method is proposed to detect the swept laser spectrum based on Stimulated Brillouin Scattering, and the experiment is implemented to measure the laser spectrum.