At Micro-and Nano Fiber Ring Resonator Electro-optic Effect

With development of communication and sensor technology , demands for miniature photonic devices have sharply grown in recent years .Due to advantage of it own optical transmission characteristics, microfiber has become a hot research field. Due to the advantage of evanescent field, the optical light can travel around such microfiber with low transmission loss and bend loss. Those optic devices relied on microfiber have easier manuafacture process than integrated optical waveguide. With low transmission loss, high Q factor quality etc, the microfiber resonator has competence over its competitors. However, there is no research report on electrooptically tuned microfiber resonator. In this thesis, we will discuss electrooptic effect of microfiber resonator under microampere range.The main research contents include as follows:1. At the beginning of the thesis, development history of the microfiber is introduced. Several kinds of microfiber resonators are presented. By introducing the current development of tunable filters based on the electro-optic effect, the thesis's main research pot of electro-optic effect of a silica microfiber knot resonator (MKR) is presented.2. As some physical characteristics are crutial for the microfiber, we analyzed the mode field characteristics of microfiber, internal and external electromagnetic field and energy distribution of fundamental mode within and outside the core. Single mode transmission condition and the factors that affect the propagation constant are also discussed. Those factors which affect the microfiber ring resonator quality, Q factor and the full width at half maximum (FWHM) are illustrated and analysed.3. Based on illustration and comparison of several typical microfiber manufacturing process, we illustrate our manufacturing process,flame heating method and polymer solven method We use a flame heating drawing process to fabricate long free-standing silicawires with 1μm in diameters and 10~15cm in length. As polymer mirofiber has competence with microfiber relied on silica in aspect to fiber diameter and bend transmission loss, we employ both methods to fabricate polymer microfiber with 2～3μm in diameter in and 20~30cm in length. We discuss the manufacture process of the microfiber resonator. Several improvements are also presented.4. The physical model of electro-optic effect in a silica microfiber knot resonator (MKR) is established.Under current tuning, the characteristic of output optical spectrum has been studied theoretically and experimentally.The experimental results show that current tuned factors by Fe and Cu are ~500pm/A and ~510pm/A. In order to detect more exact drift inducing by thermal effect, a Fiber Bragg Grating (FBG) has been employed. It shows that the thermal drift inducing by current is 21pm/A in Cu and 23pm/A in Fe. Drifts are much smaller than that caused by the electro-optic effect.By studying the on electro-optic effect of MKR, it has potential value in developing tunable filters with high Q factor.