NASA SBIR 2004 Solicitation


PROPOSAL NUMBER: 04 E1.01-8745
SUBTOPIC TITLE: Passive Optics
PROPOSAL TITLE: Mesoporous Silicon Far Infrared Filters

SMALL BUSINESS CONCERN (Name, E-mail, Mail Address, City/State/Zip, Phone)
Lake Shore Cryotronics Inc
575 McCorkle Blvd.
Westerville, OH 43082-8699

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Marc Christophersen
575 McCorkle Blvd.
Westerville, OH 43082-8699

This SBIR Phase I proposal describes a novel method to make optical filters based on mesoporous silicon multilayers, for use at cold temperatures in the far infrared spectral region. This type of filter consists of a lattice of different porosity layers formed in monocrystalline silicon by electrochemical means. Due to the nature of the material, mesoporous silicon filters do not suffer from thermal, mechanical, and environmental instabilities. More over, due to the high transparency of the mesoporous silicon throughout a large part of the far IR range, such filters can be made for wavelengths far longer than those that can be addressed with conventional interference filter technology. They will considerably outperform filters based on metal meshes. Such filters are expected to impact astronomical, commercial, military and scientific communities in many filter applications. In Phase I, it is proposed to demonstrate the feasibility of the method by fabricating porous multilayers with ultrahigh thickness and to evaluate a sintering technique to enhance environmental stability. In Phase II, optimized filters will be fabricated and their properties compared with design predictions. Phase III will involve product design, fabricating filter structures to meet customers' physical as well as optical needs, and marketing and sales investments.

Far-infrared imaging is a powerful technique to study the center of our galaxy and beyond. However, this wavelength range is difficult to work in. At these wavelengths, room temperature objects emit strongly. The strong Earth background causes weak signal-to-noise ratios. Far IR filters are needed to separate extraterrestrial signals from this background to build a meaningful picture. Currently used filters suffer from problems stemming from the lack of materials that are transparent, stable and compatible with each other at these wavelengths. The proposed type of filter can solve these problems.

Narrow band pass, band pass and band blocking mid and far IR filters are used in environmental monitoring, chemical and biological analysis, imaging and other areas. Customers include manufacturers of production equipment, as well as manufacturers and users of "consumer" optical components and equipment. Lake Shore proposes a new design for optical filters that has the potential to be an enabling technology. Hence, all these applications may be considered as potential markets for mesoporous filters.