Terahertz Quantum-Cascade Lasers and Metrology: Optimization, Measurement Standardization, and Novel Applications

Terahertz (THz) technology is advancing rapidly, driven by growing demands in high-resolution imaging, non-destructive testing, and spectroscopic sensing. However, realizing reliable, high-power THz radiation sources remains a critical bottleneck. Terahertz quantum-cascade lasers (THz QCLs) represent one of the most promising compact, coherent platforms. Recent progress has focused on heterostructure band-engineering—tuning quantum well thickness and barrier profiles to tailor subband transitions and elevate operating temperatures toward room temperature. Simultaneously, emerging material platforms such as wide-bandgap GaN heterostructures and specialized low-loss THz waveguides are expanding power thresholds and spectral reach. In parallel, the absence of standardized protocols for characterizing THz pulse intensity, spatial profiles, and absolute electric fields hampers reproducibility across laboratories, making robust metrology as critical to the field's maturity as source development itself.This Research Topic aims to connect the physical design and optimization of THz QCLs with advances in experimental metrology and characterization. By bridging device physics, heterostructure engineering, and precision measurement, this collection seeks to identify structural pathways to higher operational temperatures and output powers while establishing benchmarked metrological protocols. We welcome contributions spanning quantum transport modeling, novel material integration, near-field beam diagnostics, and standardized absolute field measurements, linking nanoscale subband design directly to calibrated macroscopic device performance.This Research Topic welcomes original research articles, reviews, mini reviews, and perspective papers. Topics of interest include, but are not limited to:-Design, bandgap engineering, and subband optimization of THz quantum-cascade lasers-High-temperature operation strategies, including wide-bandgap (e.g., GaN-based) heterostructures-Near-field properties, beam profile shaping, and mode-coupling in THz QCL architectures-Low-loss waveguides and hollow-core structures tailored for THz beam delivery and coupling-Absolute measurement and characterization of THz pulse intensity, phase, and electric field distributions-Cross-laboratory standardization protocols and calibrated metrology for THz sources-High-resolution spectroscopic sensing and non-destructive diagnostic applications driven by advanced THz sources Topic editors: Yufei Ma, ABHISHEK SHARMA Source: https://www.frontiersin.org/research-topics/85996/terahertz-quantum-cascade-lasers-and-metrology-optimization-measurement-standardization-and-novel-applications