Micromachined Optical Matrix Switch for WDM Optical Communication Networks

本研究的目的是利用微加工技术制作用于WDM（波分复用）光通信网络的N × N光矩阵开关。该开关由芯片上的N × N个可移动反射镜和2N个用于光纤对准的v型槽组成。来自N根输入光纤的光束在适当位置被N面反射镜反射，将光束连接到N根输出光纤。通过单晶硅的湿法各向异性刻蚀，制备了垂直于衬底的薄微镜和具有精确45度角的v型槽。通过在v形槽中插入纤维，可以轻松地梳尾。由于由晶体图形取向确定的精确对准，插入损耗小于1 dB。采用干法各向异性刻蚀和湿法各向异性刻蚀相结合的方法，提高了微镜的堆积密度。由于输入和输出端口之间的距离变短，耦合损耗减小。(2)自锁式电磁致动器和阵列致动器电/永磁体联合牵引固定在动镜上的坡莫合金片。永磁体使镜子的自锁操作成为可能。由于能量耗散只发生在从一种状态切换到另一种状态时，我们可以使能量消耗最小化。制作了与阵列反射镜相匹配的阵列线圈。平面线圈直径500-800微米，厚度20-50微米。我们可以在线圈中产生足够的磁场来驱动2 A的脉冲电流。(3)光学评价制作并测试了一个2 × 2初级开关。单模光纤的插入损耗为0.8 dB，切换速度为2 ms，对比度为50 dB，使用寿命超过2000万次。

The purpose of this research is to fabricate an N x N optical matrix switch by micromachining technologies for WDM (wave division multiplex) optical communication networks. The switch consists of N x N movable mirrors on a chip and 2N V-grooves for optical fiber alignment. The optical beams from N input fibers are reflected by N mirrors at appropriate positions to connect light beams to N output fibers. We have obtained the following results :(1) Pre-aligned micromirrors and V-grooves by micromachiningThin micromirrors that are vertical to the substrate and V-grooves that have exact 45 degree angles were fabricated simultaneously by wet anisotropic etching of single crystal silicon. Easy pig-tailing was possible by inserting fibers in V-grooves. The insertion loss was less than 1 dB because of precise alignment determined by crystal graphic orientation. Higher packing density of micromirrors was achieved by combining dry anisotropic etching and wet anisotropic etching subsequently. The coupling loss decreased because the distance between input and output ports became shorter.(2) Self-latching electromagnetic actuation and arrayed actuatorA permalloy piece attached to the moving mirror was pulled by a combined electro/permanent magnet. The permanent magnet enabled the self-latching operation of the mirror. Because energy dissipation occurs only at the switching from one state to another, we could minimize the energy consumption. Arrayed coils that match the arrayed mirrors were fabricated. The planar coil was 500-800 micrometers in diameter and 20-50 micrometers in thickness. We could generate enough magnetic field for actuation with 2 A pulse current in the coil.(3) Optical evaluationA 2 x 2 elementary switch was fabricated and tested. It had insertion loss of 0.8 dB with single mode fibers, switching speed of 2 ms, contrast of 50 dB and lifetime of more than 20 million operations.