Advances in Front-end Enabling Technologies for Thermal Infrared ‘THz Torch’ Wireless Communications

Abstract

The thermal (emitted) infrared frequency bands (typically 20-40 THz and 60-100 THz) are best known for remote sensing applications that include temperature measurement (e.g., noncontacting thermometers and thermography), night vision and surveillance (e.g., ubiquitous motion sensing and target acquisition). This unregulated part of the electromagnetic spectrum also offers commercial opportunities for the development of short-range secure communications. The ‘THz Torch’ concept, which fundamentally exploits engineered blackbody radiation by partitioning thermally-generated spectral radiance into pre-defined frequency channels, was recently demonstrated by the authors. The thermal radiation within each channel can be independently pulsemodulated, transmitted and detected, to create a robust form of short-range secure communications within the thermal infrared. In this paper, recent progress in the front-end enabling technologies associated with the ‘THz Torch’ concept is reported. Fundamental limitations of this technology are discussed; possible engineering solutions for further improving the performance of such thermalbased wireless links are proposed and verified either experimentally or through numerical simulations. By exploring a raft of enabling technologies, significant enhancements to both data rate and transmission range can be expected. With good engineering solutions, the ‘THz Torch’ concept can exploit 19th century physics with 20th century multiplexing schemes for low-cost 21st century ubiquitous applications in security and defence.