The Design And Research Of Visible Wavelength Division Multiplexer Based On Photonic Crystal Defect Structure

Photonic crystal is a new type of artificial materials, which plays a more and more important role in the integrated technology and devices, because of two basic characteristics of photonic crystal: photonic band gap and photon localization, and its high integrated, high efficiency, low loss and small volume. Photonic crystal wavelength division multiplexer(WDM) is currently very active hot-direction in the field of optical devices of photonic crystal. Most research of photonic crystal WDM is concentrated in the communication band, and little research is concentrated on operating wavelength in visible-light band. Photonic crystal visible-light WDM is an important supplement to the research of optical integrated devices.This paper designed optical wavelength division multiplexer based on the structure of photonic crystal defects, and the main research works are as follows:1. Gallium phosphide(Ga P) was selected as the photonic crystal dielectric materials, which has large refractive index and low extinction coefficient in visiblelight band. The relationship between duty ratio and photonic crystal band gap for TE polarization was analyzed. The structural characteristics, the transmission characteristics, the band gap characteristics and local frequency of the three defect structures of photon crystal waveguide, micro-cavity and ring resonator were studied by using the plane wave expansion(PWE) and the finite difference time domain method(FDTD), providing the basis for the design of photonic crystal visible WDM.2. The theory of coupling model was used to calculate the coupling lengths corresponding to the light waves of 488 nm, 532 nm and 635 nm. We controlled the light in a cross state or direct state by reasonable design of structure parameters, while increased the medium column density of the input and output ports. Three-visible-light splitter based on photonic crystal waveguide coupling was designed, and effective partial of the three wavelengths was realized.3. The relationship between the center resonant frequency of micro-cavity and the radius of defect was analyzed by FDTD. The radii of defect corresponding to light waves of 488 nm, 532 nm and 635 nm were found. Using the direct coupling structure of waveguide and micro-cavity, we designed the photonic crystal visible-light WDM, which increased the reflection micro-cavities in the original structure, making the transmissions of the three work wavelengths over 90%.4. Three-visible-wavelength combiner based on photonic crystal waveguide, micro-cavity and ring resonator was proposed. Light wave of 635 nm entered the main waveguide through ring resonator, while light waves of 488 nm and 532 nm through corresponding micro-cavities. This combiner realized the three wavelengths of visible light combine that was very small size and very high efficiency.