Ring Laser Gyroscopes by MEMS Technology

在本研究项目中，我们建立了基于MEMS的环形激光陀螺(MEMS RLG)的基本技术。首先，我们提出了一种基于(111)面湿法各向异性刻蚀单晶硅(110)面的光学闭环镜。对最佳刻蚀条件、错位效应等进行了研究，发现在最佳刻蚀条件下得到的(111)面反射镜具有足够的光学质量。用光敏环氧树脂实现了透镜、棱镜等光学元件，并对它们的光学特性进行了测试，证实了它们在光学器件中的应用。此外，还用该树脂制作了激光二极管芯片的对准和结块结构。然后，我们将镜面制造工艺和基于环氧树脂的工艺批量地结合在一起，实现了批量生产和低成本。为了提高反射镜的反射率，我们开发了硅表面直接镀金技术。这项技术省去了通过溅射或蒸发在每个反射镜上沉积金属薄膜的复杂过程。上述许多技术不仅对MEMS激光陀螺，而且对许多光学MEMS领域的器件都是非常有用的。现在，我们有计划与一些行业合作，开发可以投放市场的MEMS激光陀螺仪。

In this research project, we have established basic technologies for MEMS-based Ring Laser Gyroscope (MEMS RLG). At first, we newly suggested an optical closed-loop by (111) mirror which results from wet anisotropic etching of single crystalline silicon-wafer with (110) surface orientation. The optimum etching condition, effect of miss-alignment, etc. were investigated and we found that the (111) mirror have sufficient quality for an optical mirror at the optimum conditions. Other required optical elements such as lenses and prisms were realized by photo-sensitive epoxy resin and their optical characteristics were examined and confirmed that they are useful for optical-devices. Moreover, alignment and clumping structures for laser diode chip were also constructed by this resin. Then, we combine the mirror fabrication-process and epoxy-resin based process in batch manner, which enables mass production and low cost. In order to improve reflectance of the mirror, we developed direct gold-electroplating technique for silicon surface. This technique eliminates the complicated process to deposit a metal film to the each mirrors by sputtering or evaporation. Many numbers of techniques mentioned above are very useful not only for MEMS RLG but for many devices in optical MEMS field. Now, we have a plan of collaboration with some industries to develop the MEMS RLG which can be put on the market.