I am particularly interested in the applications of THz QCLs. The goal is to build a sensitive and compact coherent THz heterodyne transmitter/receiver (transceiver) system based on THz QCLs and Schottky diode balanced mixers. In order to advance in development of a compact THz QCL-based transceiver system, some THz QCL parameters (spatial and temporal coherency) still need to be addressed. Such systems will find new applications and replace existing sources and receivers, whose deficiencies include size, complexity and cost. The University of Massachusetts in Lowell is in a unique position having MBE growth, device fabrication, and characterization facilities in the same place to complete the proposed THz transceiver project.