Heterojunction GeSn based Photonic Devices

ABSTRACT: Si photonic devices based on GeSn materials will be very important for the MWIR. The Air Force recognizes the need for next-generation high-performance photonic materials in the SWIR to MWIR infrared spectrum, due in part to the atmospheric high transmissive windows in this wavelength ranges. Due to materials limitations, silicon based photonic devices have not been utilized in this wavelength region. The development of cost effective large area SWIR-MWIR focal plane arrays would be very important for Department of Defense applications for night time surveillance, missile acquisition and tracking, and imaging through the atmosphere. Also there is strong interest in this technology for applications of airborne imagery for detecting gaseous effluents in the atmosphere. Molecular gases have exhibit unique spectral signatures in the IR allowing for detection and identification. Many absorption lines of gas molecules lie in this IR spectral region such as the distribution of different gases for explosives and bio-agent detection. Mid-IR lasers for enhancing performance of directional infrared countermeasures (DIRCM), which can defeat missile IR seekers with laser-jamming wavelength-blocking countermeasures. Silicon based emitters and detectors will allow for the development of lower cost, large area photonic devices required for these applications. BENEFIT: Mid-infrared (mid-IR) wavelength lasers and detectors can be used for molecular spectroscopy and telecommunications, and have many applications including both civilian and military due to the high transparency atmospheric windows (chemical detection, LIDAR, infrared countermeasures, secure communications). Si lasers and detectors for the computer applications, inter-chip and intra-chip communications are important as problems of routing which keep silicon circuits two dimensional could be avoided and ultra dense chips using 3-D architectures where light transmits data throughout the chip could be achieved. Medical applications related to the high absorption in tissues at these wavelengths, and the flexible delivery by fiber optics would be important for medical diagnostics. Environmental monitoring of green house gases is increasingly important. Measuring atmospheric gas concentrations and the high sensitivity detection of these gases in the mid-IR allows for more portable and sensitive spectroscopic detection equipment. Sensors could be built to protect miners, to monitor industrial processes gas sensing include pollution monitoring of factory and automobile emissions. Astronomical commercial applications include analyzing meteorites, galaxy mid-IR emissions, etc. Large focal plane development results in greater telescopic throughput, and can dramatically multiply the data output for astronomical observation.