High-speed Resonant-Cavity Infrared Detector Arrays and Narrow-Linewidth Quantum Cascade Lasers for Free Space Communication Links

The ever-growing need for high-data rate, low-latency, secure, wireless communications driven by applications ranging from vehicle automation to ad-hoc battlefield command and control necessitate free space communication links (FSCLs) operating outside of the regulated and crowded rf-frequency bands. Intraband and NRL, working with the UW-Madison as the STTR Research Partner, propose to investigate the feasibility of FSCLs based on the UW/Intraband 2.5-W MOCVD-grown QCL technology and the NRL resonant-cavity infrared detectors (RCIDs) when optimized for modulation bandwidth > 5 GHz, transmitter power > 1 W, narrow linewidth, and link signal to noise ratio. The RCID resonant cavity reduces the absorber thickness required to achieve high quantum efficiency in the detector. This reduced thickness reduces the dark current, increases specific detectivity, and decreases carrier transit time. The ~ 50-nm optical bandwidth of the RCID also aids in rejecting background radiation but requires a QCL with narrow linewidth. Intraband will work with the UW Madison to design and model high-power, narrow-linewidth QCLs optimized for high-speed modulation. NRL will investigate the feasibility of > 5-GHz bandwidth for a MWIR RCID and provide modeled device characteristics for devices and arrays. Intraband will develop a link model with projected performance based on simulated device characteristics.