Omnidirectional Narrow Band Pass, band Pass and Band Blocking IR Filters

This Small Business Innovation Research Phase I project will address the feasibility of narrow band pass, band pass and band blocking optical filters, with very wide acceptance angles, made from macroporous silicon. In currently available filters based on interference in a multilayer stack, the transmission spectra depend on angle of incidence. Omnidirectional filters are clearly needed to simplify optical alignment and allow simpler utilization of non-collimated light beams. A new type of optical filter is proposed as a basis for such filters. The proposed optical filter will be made of a three-dimensional, periodic structure in monocrystalline silicon. In Phase I, the feasibility of such filters will be demonstrated by fabricating a filter structure and measuring its physical and optical properties. The feasibility study will concentrate on the near infrared spectral range, although similar principles can be applied out to the mid-IR. In Phase II, filters for different wavelength ranges will be fabricated and their performance will be optimized to meet the designed bandwidth, insertion losses, and out-of-band transmission. Phase III will involve product design and fabrication of physically robust filter structures to meet customers? requirements, and will include the necessary marketing and sales investments.