侧链型聚合物DANS-PMMA脊形条波导的制备

Fabrication of Ridge Channel Waveguide for DANS-PMMA Side-chain Polymer

有机聚合物的紫外漂白 ,经过一系列复杂的光化学反应 ,会使聚合物薄膜的折射率和厚度降低。在此基础上 ,利用金属掩模对聚合物薄膜进行选择性紫外漂白 ,制备出聚合物脊形条波导。紫外漂白不需要对聚合物薄膜进行光刻和腐蚀便可获得边缘和表面比较整齐和光滑的脊形条波导 ,对减少波导的散射损耗十分有利。本文介绍了利用紫外漂白和金属掩模方法制备侧链型聚合物DANS( 4 dimethylamino 4’nitro stlibene) PMMA( polymethylmethacrylate)脊形条波导的工艺过程 ,并对关键工艺进行了讨论。

Organic nonlinear optical materials have stimulated much interest for their large nonresonant nonlinearities, high speed response, ease of fabrication and low cost. There are a number of different ways to fabricate polymer channel waveguides, such as reactive ion etching and groove filling etc. This paper reports a simple technique of UV photobleaching which can be used to prepare ridge channel waveguide with DANS (4 dimethylamino 4'nitro stlibene) PMMA (polymethyl methacrylate) side chain polymer film. UV photobleaching is an attractive method for fabricating polymer optical waveguides because the process is simple and exposure time can be adjusted easily, so as to control the refractive index changes of the polymer film. The corresponding main technique is discussed in the paper. The complicated photochemical reaction will happen when DANS PMMA side chain polymer film is exposed to the high pressure Hg lamp. We can notice that both the refractive index and the thickness of the DANS PMMA film are reduced after photobleaching. This process is usually called UV photobleaching of the polymer film. For DANS PMMA film, we have processed a series of UV photobleaching experiments. Under appropriate UV photobleaching condition, combined with metal covered technique, a new type of DANS PMMA polymer ridge waveguide was prepared. First, the Al film was deposited on the surface of DANS PMMA film and formed pattern of waveguide by photolithography and etching. Second, the sample was exposed to the high pressure Hg lamp for some time. Then, the new type of ridge waveguide is formed. Besides, the technique does not require photolithography or etching on polymer film, so very flat waveguide side walls can be formed. With the microscope we can observe the perfect shape of the DANS PMMA ridge waveguide . The smooth walls of the ridge waveguide are helpful to reducing the scattering losses and improving the quality of the waveguide. The experiment proved that UV photobleaching process depended on time, distance and temperature of bleaching. The rate of UV photobleaching will increase when environment temperature is risen.