Nano-Structured Multi Band Visible to Long-Wavelength Infrared Detectors

The aim of this proposal is to satisfy the U.S. Air Force (USAF) requirements for multi-mode sensing (spatial, spectral, polarization, etc) detectors without external components such as filters and polarizers. The main part of the work will involve the development of a four-band detector with wavelength selection capability without using optical filters based on a new device concept. The spectral bands covered are visible-near infrared (VIS/NIR: 0.5-0.9 µm), short-wave-infrared (SWIR: 0.9-2 µm), mid-wave-infrared (MWIR: 3-5 µm), and long-wave-infrared (LWIR: 8-14 µm). The approach for achieving this challenge is to use a back-to-back connected pin diode architecture with In0.53Ga0.47As/InP quantum wells embedded in it as light absorption elements, which is called npn-QWIP. This material system is capable of covering the four wavelength bands specified before and providing the selection of two wavelength bands (VIS/NIR + MWIR or SWIR + LWIR) at a time based on the applied bias polarity. In addition, we will also use metal grids (1D or 2D) as a light coupling method as well as polarization sensitive elements. BENEFIT: A major constrain associated with multi-color detectors is the inability to select response regions without using optical filters and multi-terminal electrical contacts on the detector. The use of optical filters not only reduces the radiation transmission but also makes the detector system bulky and complicated. Having multiple electrical contacts requires sophisticated processing techniques. In this work, the feasibility of four-band detectors providing wavelength selectivity based on the bias voltage polarity alternation will be demonstrated. Hence, the proposed detectors will not need external optical components or electronics for wavelength selection, giving an immense advantage over the existing detectors. Weight will be much less, providing easy maneuverability. In addition, this work will also address the possibility of covering a wide wavelength region from VIS to LWIR using a single device. In addition to the USAF which would benefit from the development of polarization sensitive detectors, the IR detector market covers a wide range, which has a market capitalization of tens of billions of dollars. Some applications include: security and surveillance, geology, agriculture, disaster relief, automobile industry, drug enforcement, and Astronomy applications.