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26 September 2007 Development of components for cost effective terahertz measurement system: terahertz quantum cascade laser and terahertz quantum well infrared photo-detector
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Proceedings Volume 6772, Terahertz Physics, Devices, and Systems II; 67720R (2007)
Event: Optics East, 2007, Boston, MA, United States
Terahertz imaging and spectroscopy have attracted a lot of attention in recent years, because monocycle terahertz radiation can be generated using an ultra-short pulse laser and semiconductor device technologies. The availability of monocycle terahertz radiation sources has encouraged innovative research and development activities worldwide in an extremely wide range of applications, from security to medical systems. However, the fundamental device technology, namely the semiconductor emitter, amplifier, modulator, focal plane array detector, and optical thin film among others, in the terahertz frequencies has not yet been fully established. Therefore, a measurement system in the terahertz range remains a costly alternative. We report in this paper our recent developments of a terahertz quantum cascade laser (THz-QCL) and a terahertz quantum well photo-detector (THz-QWIP). We believe that the combination of a semiconductor emitter (THz-QCL) and a semiconductor detector array (THz-QWIP) is a good choice for developing a cost-effective measurement system for a given terahertz range (from 1.5 THz to 5.0 THz), because both of these items are based on mass-production semiconductor fabrication techniques. We fabricated the THz-QCLs using a resonant longitudinal-optical phonon depopulation (RPD) scheme, which is made up of both a GaAs/AlGaAs material system and a GaSb/AlGaSb material system. The GaAs/AlGaAs THz-QCL has already successfully demonstrated a high peak power (about 30 milliwatts in pulsed operation) operation at 3.1 THz and a high operating temperature (123K). On the other hand, we have fabricated a THz-QWIP structure consisting of 20 periods of GaAs/Al0.02Ga0.98As quantum wells with a grating coupler on the top of detector devices, and successfully operated it at 3 THz with a responsivity of 13mA/W. We now believe we are ready to make a cost-effective measurement system, although both of the devices still require cryogenic coolers.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Iwao Hosako, Norihiko Sekine, Mikhail Patrashin, and Hiroaki Yasuda "Development of components for cost effective terahertz measurement system: terahertz quantum cascade laser and terahertz quantum well infrared photo-detector", Proc. SPIE 6772, Terahertz Physics, Devices, and Systems II, 67720R (26 September 2007);

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