Theoretical Study On Characteristics Of Propagation And Switching In Microresonator System

For the rapidly increasing of information quantity and the improved requirements of people oncommunication, the existing network has been unable to support various increasingtelecommunication service. Then, we need a new network to solve the problem of electronicbottleneck. In the present, the all-optical-network is the best choice. It doesn’t needoptical-to-electronic conversion, and all the transmission and exchange will perform in the opticaldomain. As a consequence, it can solve the problem of bandwidth limitation in existing network.However, the realization of all-optical-network depends on various kinds of optical devices whichhave different performance. And the microresonators have attracted considerable attention in theresent year due to their various advantages, such as small size, simple structure and stableperformance.The specific research works and results are as follow:1. This paper explains the basic principle of optical fiber coupler. And the derivation process ofcoupling matrix of fiber coupler is introduced according to the coupled-mode theory. The couplingmechanism between microresonator and straight waveguide is similar to the optical coupler’s, andthey all follow the same rules of coupling. As a consequence, the theoretical models of single-ringmireoresonator and through/drop microresonator are established based on the optical fiber coupler.Utilizing the coupling matrix of fiber couples, thesis derives the output signal transmissivity ofsingle-ring mireoresonator and through/drop microresonator. In addition, the paper analyzes thepropagation performance of those two systems, and the curves of the propagation performance areshowed in the paper, which contain output signal transmissivity, transmitted phase shift andtransmitted time delay.2. For the single-ring mireoresonator system, this paper mainly studies the influence ofcoupling coefficient on the resonance performance of microresonator. When increasing the couplingcoefficient, the slope of curve of phase shift around the resonance will decrease, and the output timedelay at resonance points will also decrease. At the same time, the bandwidth of output slow light isbroadened. And in the presence of the gain within microresonatot, one simulates the curve betweengain and output time delay. The investigation reveals that the increase of gain leads to an increase ofthe output time delay at the resonance points. Furthermore, the adjustable range of time delay isrelative to the coupling coefficient. What’s more, the schematic of the double-ring micreresonatorsystem is introduced. After introducing its working principle, the propagation performance of double-ring micreresonator system is centered on in this paper. The research reveals that the numberof resonance points depends on the coupling coefficient between two microresonator. The originalresonance point will split into multi resonance points with the increasing the coupling coefficient.And the gain within microresonator will influence the output time delay of system. The increasingof gain lead to a decrease of the time delay of transmitted wave at the resonance points, and anincrease of the time delay of reflected wave. Thus, it can be seen that one can utilize gain todynamically control the group delay in active microresonator system no matter single-ring ordouble-ring, which lays the theoretical foundation for optical buffer.3. The paper analyses the propagation performance of the through/drop microresonator systemin the nonlinear case. Inputting one continuous wave, the nonlinear effect of self-phase modulationwithin microresonator will induce the shift of resonance frequency. Making use of that property, thechange of input power can lead to the nonlinear switching between two output ports of through/dropmicroresonator system at various frequencies. And the decrease of the detuning frequency of inputsignal results in the decrease of threshold power of nonlinear switching. Furthermore, the steepnessof switching is depending on the coupling coefficient. When the input power is not big enough, weuse frequency modulation to turn on the nonlinear switching. And the microresonator system needsa large modulation depth if the input power is small. What’s more, this paper proposes afrequency-tunable filter based on micro-ring resonator. The characteristic of this filter is that themicro-ring consists of the electro-optic (EO) polymer materials, where the left and right electrodesare placed at the same electric potential. By adjusting the electric potential in the left and rightelectrodes, the effective index of refraction of the waveguides consisting of OE polymers undergoesa change, which leads to the modification of resonance wavelength and to frequency tunablefiltering. And our research reveals that the increase of applied voltage leads to an increase of theFSR and the finesse of the resonator system. Furthermore, time delay in the resonance point of dropport will increase gradually with increasing the voltage.