硅基二维光子晶体耦合器理论研究

光子晶体是一种具有光子带隙的新型人工材料，利用其具有控制和限制光子运动的特性可以制成新颖的光学器件。利用硅基二维光子晶体，提出了一种4端口耦合器。采用时域有限差分法作为研究工具，TM模作为研究对象，从理论上分析了这种器件的特性。在不同的耦合长度下研究光在输出端的功率透射率。结果表明选择适当的耦合长度可以使光在器件中呈现不同的状态。进一步研究表明，通过改变器件内部介质柱的半径，可以改变光在输出端的输出功率。从而证实了这种器件不仅具有波长选择性，而且具有潜在的可调节性，这些特性使得这种器件在全光开关的应用上具有潜在的优势。

Theoretical Study of Silicon-Based Two-Dimensional Photonic Crystal Coupler

Photonic crystal is a new artificial material. Its unique optical properties enable it to be used in fabricating novel optical devices. In this work, a 4-port coupler is proposed theoretically in silicon based on twodimensional silicon photonic crystals, The optical properties of the 4-port coupler device have been demonstrated for TM polarization by finite-difference time-domain method. Transmittivity in each output port of the device is given as a function of coupling length. Results show that propagation direction of the input light beam can be controlled by changing coupling length of the device. Further studies indicate that the output optical power in each output port of the device can be tuned by reducing the radii of the silicon rods in the photonic crystals. The properties make the device find its potential applications in all-optical switching systems with wavelength-selective and tunable properties.