Research On Ploymer Multi-Cladding Polymer Electro-optic Modulator Based On Long Period Fiber Grating

The modulator is one of the most important optical devices in high speed optical fiber communication system, the performance of the system directly determines the performance of the system. Compared with other types of modulator, electro-optic modulator is simple, easy to realize broadband modulation, due to its low production cost, production process which has been more attractive. In this paper, we mainly study multi-cladding polymer electro-optic modulator based on long period fiber grating, the most significant characteristic of the modulator is that multi-wave length modulation can be realized, low driving voltage under high speed modulation can be realized with long period fiber grating, due to its high sensitivity to external medium. This paper focuses on the analysis of the waveguide structure and the modulation process of the multi-cladding polymer long period fiber grating electro-optic modulator, and the main work is as follows:1. Introduced the background, progress and significance of electro-optic modulator, analyzed the working principle of different kinds of electro-optic modulators, and the properties of poled polymer materials.2. Analyzed the basic characteristics of multi-cladding polymer electro-optic modulator based on long period fiber grating, including the mode field distribution and mode effective refractive index of multi-cladding optical waveguides, the relationship of between poled polymer and electro induced index rate variation, long period fiber grating coupled mode equations, transmittance and coupling constant parameters.3. Analyzed multi-cladding optical waveguide structure, including the thickness and refractive index of each layer which affected on the propagation constants. Analyzed the period and the length of the long period grating which affected on the transmission spectrum characteristic. The theoretical basis is provided for selecting suitable multi-cladding optical waveguide structure parameters and long period fiber grating parameters.4. Analyzed modulation performance of multi-cladding polymer long period fiber grating electro-optic modulator and the multi-wave length modulation characteristics, including the eye diagram of long period fiber grating electro-optic modulator in different modulation rate. The results showed that when the driving voltage was less than 3V the modulator can be realized the single wavelength modulation, the change of output power is 19dB, when the driving voltage was less than 10V the modulator can be realized the dual wavelength modulation, the change of output power is 11dB and 45dB.