Agile InAlAs/InGaAs Multi-Quantum Well Fabry-Perot Filter

Band-gap-resonant optical non-linearities in III-V compound semiconductor materials provide the basis for novel components, allowing advances in optical signal processing. Of particular interest to future Air Force efforts are electrically tuned multi-element spectral filters, which can be utilized in spectral imaging and automated target recognition (ATR) systems. Other applications for this technology would be optical interconnects, computing, communications, and logic circuits. We propose to prepare a tunable Fabry-Perot spectral filter using MOCVD crystal growth. An advanced InAlAs/InGaAs multi-quantum-well structure will be developed which will exhibit the lateral electric-field-induced refraction (LEFIR) effect, leading to a tunable filter. The lightwave propagates transverse to a stack of layers, while the electric field, applied in the lateral direction, induces changes in the refractive index of the active region containing the quantum wells. The index change results from the removal of a two-dimensional electron gas, which is supplied by planar doping. Configured as a Fabry-Perot interferometer using two stacks of Bragg mirrors, the transmissive modes are shifted in wavelength when the effective refractive index of the active region is altered by the applied field, creating the filter. In Phase II, the work will be expanded to create fully operational two dimensional arrays of these tunable optical filters.