Terahertz imaging using quantum cascade lasers—a review of systems and applications

Terahertz Pulse Detection Techniques and Imaging Applications

“…As such, the source is useful for many TPI applications such as long-range imaging and materials analysis. The QCL-based THz imaging approaches and their key advancements are reviewed [54]. Another example is that by utilizing a split tapered waveguide with a subwavelength aperture, near-ield THz imaging is accom-…”

Terahertz quantum cascade lasers — The past, present, and potential future

“…Initial research focused on techniques based on bolometric detection using room temperature, or cryogenically cooled, single-pixel or array detectors. But, more recently, it has been shown that the emitting QCL cavity itself can be used as a radiation selfdetector, providing system miniaturization, and absorptioncoefficient-sensitive reflection imaging (for a review, see [13]). This Ôself-mixingÕ approach has been highly successful, and it has been possible to demonstrate: displacement sensing interferometry [14]; two-dimensional imaging [15], imaging over distances exceeding 10 m [16]; and, swept frequency coherent imaging, enabling the measurement of porcine tissue [17], inter alia.…”

Extraction-controlled terahertz frequency quantum cascade lasers with a diagonal LO-phonon extraction and injection stage

“…To date, their emission frequency has covered the range from 1.2 THz to 5.2 THz [6,7], and the maximum peak output power has reached 1.01 W in pulsed mode at 10 K [8]. These improvements now establish THz QCLs as promising sources for many applications including THz spectroscopy, remote sensing and THz imaging [9,10]. However, the maximum operating temperature of THz QCLs to date is only 199.5 K [11], which limits their practical use in many applications outside the laboratory environment.…”