Study On Porous Silicon-based Optical Rugate Filter Technology

The porous silicon photonic devices have potential applications due to its refractive index can be easily changed by controlling the etching conditions during the production process. Porous silicon-based rugate structures having a sinusoidal refractive index variation with depth, can improve the performance of the optical devices. Single and multiple bandgap rugate filters have been widely applied to chemical and biological sensors in the near-infrared spectral range.Based on electrochemical etching theory of silicon, Porous silicon-based rugate filters working in the near-infrared spectral range were fabricated by electrochemical anodization of p-type crystalline silicon. In order to improve the emitting light quality of filters, firstly,influence factors on reflection spectral characteristics of rugate porous silicon were investigated. Then, using the index-matching technology, boundaries of the structure were introduced the index-matching layers having a thickness of 5.1?m, it effectively reduce the strength of the interference fringes and second-harmonic peak. Finally, the extend-bandwidth rugate filters with band width of 1350 nm was prepared through combining of several rugate filters in serial method, and in the same way, a double stop band filter was also prepared.