光开关是集成光路上一个重要的元器件。提出了一种用在L和C波段基于硫系相变材料（Ge₂Sb₂Se₄Te₁）的片上2×2定向耦合器式的可重构光开关，可通过改变相态切换开关。利用仿真软件Lumerical中的Mode Solutions和FDTD Solutions模块设计器件，得到在1500～1625 nm内耦合长度为24.9 μm的Ge₂Sb₂Se₄Te₁非晶态下插入损耗（IL）＞−0.36 dB，串口对比度（CT）＜−24 dB；Ge₂Sb₂Se₄Te₁晶态下IL＞−0.44 dB，CT＜−30.46 dB。利用仿真软件COMSOL模拟532 nm波长激光加热Ge₂Sb₂Se₄Te₁，结果显示：一个25 ns、峰值功率45 mW的高斯短脉冲可以使材料由晶态转化为非晶态；施加多个峰值功率20 mW、周期1 μs且占空比0.03%的高斯脉冲阵列可重回晶态。仿真结果表明，设计的光开关在通信波段通过激光加热可以快速实现切换光路的作用。

Optical switch is an important component of integrated optical circuit. In this paper, an on-chip 2×2 directional coupler reconfigurable optical switch based on one kind of chalcogenide phase change materials (Ge₂Sb₂Se₄Te₁) used in the L and C bands was proposed. The switch can be switched by changing the phase state. The optical switching device was designed by means of Mode and FDTD Solutions in the simulation software Lumerical. The results showed that the insertion losses (ILs) were more than -0.36 dB and the crosstalks (CTs) were less than -24 dB in the amorphous state of Ge ₂Sb₂Se₄Te₁ with a coupling length of 24.9 μm in the band from 1500 nm to 1625 nm. The ILs were more than 0.44 dB and the CTs were less than -30.46 dB in the crystalline state. Multi-physics simulation software COMSOL was used to simulate 532 nm wavelength laser heating Ge ₂Sb₂Se₄Te₁. The results showed that a 25 ns short Gaussian pulse with a peak power of 45 mW could transform the material from a crystalline state to an amorphous state. Applying multiple Gaussian pulse arrays with a peak power of 20 mW, a period of 1 μs and a duty cycle of 0.03% could bring it to the crystalline state. Simulation results showed that the designed optical switch can quickly switch optical path in the communication band by laser heating.