Materials for Terahertz Frequencies

We propose to develop a novel source of THz radiation based on monolithic integration of dual wavelength Quantum cascade laser (QCL) and intersubband difference frequency generator (DFG) with Cerenkov phase-matching. In addition we propose to demonstrate a novel 3-frequency coherent heterodyning detection scheme using a QWIP as a mixer/detector element with an estimated NEP of 10-17W/Hz(1/2). The THz source will use electrical pumping, incorporate monolithic integration, exhibit room temperature operation, and have a wall plug efficiency of up to 1%. In addition it will have a compact size (determined only by a power supply) and is potential tunable. The key features of our approach for the THz source are: (1)The use of a room temperature dual-wavelength QCL laser for intra-cavity pumping; (2) The use of intra-cavity asymmetric coupled QW’s for difference frequency generation in the THz range; (3) The use of Cerenkov -type phase matching for efficient out-coupling of THz radiation; (4) Achieving tunability of the THz radiation based on frequency tuning of the QCL. Key features of the detection scheme is the use of 2 individual mid-IR QCLs as heterodyning sources and a QWIP as a combined mixer/detector element.