Laterally varying porous silicon optical tunable filter fabricated using a tapered etch mask pattern

We fabricated a laterally varying porous silicon (pSi) Fabry-Perot tunable filter by employing the spatially graded pSi etch technique through a tapered etch mask pattern. Reflectance measurements revealed that the tuning range can be made as wide as ~100 nm while the typical transmission bandwidth is ~3 nm in the 1550 nm wavelength range.