将五光子晶体单模波导平行、邻近放置构成定向耦合器,依据自映像原理,数值分析了输入光场对称入射时,该系统中光的传播行为。基于此结构,设计了1×3光分束器,其器件长度可短至14.26 μm。仅仅通过对称地改变耦合区中两个介质柱的有效折射率,使光场在横向发生重新分布,便可实现输出能量的均分或自由分配。通过非对称地改变耦合区中的一个介质柱,可实现3个输出端的输出能量的自由分配。该光分束器具有微小尺寸和各输出端输出能量的比例可自由调制的特点,在未来集成光回路中具有广泛的应用价值。

Directional coupler can be constructed by parallelly putting five photonic crystal waveguides together. The propagation of the optical field entering this system symmetrically is analyzed numerically on the basis of self-imaging principle. 1×3 beam splitter,whose length can be as short as 14.26 μm,is designed by using this structure. By symmetrically tuning the effective refractive index of two dielectric rods in the coupler,and accordingly inducing the redistribution of the electric field,equipartition or free distribution of output energy can be achieved. By asymmetrically tuning the effective refractive index of one dielectric rod in the coupler,free distribution of output energy can also be achieved. Due to the ultracompact size and the free modulation of output energy,the device has extensive practical value in future photonic integrated circuits.