提出了一种调节液晶光子晶体光子带隙的方法。二维三角介质柱形光子晶体位于2块熔凝石英片之间，在介质柱之间填充各向同性排列的液晶，受偏振紫外光照射后，光诱导液晶分子定向排列，通过光诱导液晶分子取向改变液晶的折射率。数值模拟结果表明：通过外界光场控制所填充的向列相液晶分子的方向可以对这种二维三角形介质柱光子晶体的禁带结构进行调节。该可调光子晶体可控制波导中TM模和TE模的选择性传输，因而可应用于制作全光光开关。

A novel method to control the photonic band gap of 2-D photonic crystal is proposed.The two-dimensional photonic crystal,which composes of triangular dielectric cylinders between which liquid crystal (phenylacetylene) is filled,is placed between two vitreosil substrates. After the liquid crystal in the isotropic arrangement is illuminated by polarized UV light,the lightinduced liquid-crystal molecule arranges orientationally. Results of numerical simulation show that the structure of the forbidden band of the 2-D triangular photonic crystal can be tuned by manipulating the photoinduced direction of the nematic LC molecules by the aid of external light field. Since the selective transmission of TM-and TE-polarized modes in the waveguide can be controlled by the adjustable photonic crystal,it can be used to manufacture the all-optical switch in photonic integrated circuits.