We report terahertz quantum cascade lasers operating in pulsed mode at an emission frequency of 3 THz and up to a maximum temperature of 178 K. The improvement in the maximum operating temperature is achieved by using a three-quantum-well active region design with resonant-phonon depopulation and by utilizing copper, instead of gold, for the cladding material in the metal-metal waveguides.

Over the past decade, demonstration of frequency combs has been reported in a wide range quantum cascade lasers. These have huge potential applications, including spectroscopy, sensing, imaging, and communication domains. In this perspective review, we explore modeling experimental state art on mid-infrared terahertz lasers, 10 years since first demonstrations that these devices can spontaneous...

We demonstrate measurements of the alpha factor of a distributed-feedback quantum cascade laser (QCL) by using a newly modified self-mixing interferometric technique exploring the laser itself as the detector. We find a strong dependence of the alpha factor on the injection current, ranging from -0.44 at 120 mA to 2.29 at 180 mA, which can be attributed to the inherent physics of QCLs.

We used a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier for THz time-domain spectroscopy. A THz input pulse is generated inside a QCL by illuminating the laser facet with a near-IR pulse from a femtosecond laser and amplified using gain switching. The THz output from the QCL is found to saturate upon increasing the amplitude of the THz input ...

AbstraeL Real lasers show inuinsic noise well above the standard quantum noise limit. We review the propenies of lasers and of techniques to suppress this noise. Experimental results of elenroqxic feedback techniques and of squeezing in a sewnd harmonic genenuor are presented. pinally we show that the optimum light s o w e could well be a cascade of different cavities, each one performing a spe...

A characteristic feature of quantum cascade lasers is their unipolar carrier transport. We exploit this feature and realize nominally symmetric active regions for terahertz quantum cascade lasers, which should yield equal performance with either bias polarity. However, symmetric devices exhibit a strongly bias polarity dependent performance due to growth direction asymmetries, making them an id...

Solid state terahertz (THz) lasers were made possible through the rapid progress in quantum cascade lasers (QCLs) [1]. Despite the advances in mid-infrared (MIR) QCLs [2], THz QCLs remain difficult to fabricate. The tolerances in alloy composition, layer thickness, and doping are lower for THz QCLs than their MIR counterparts. Typical THz structures can require more than a day to grow by MBE an...

ABSTRACT We show that QC laser could improve capillary Gas Chromatography Infrared spectroscopy resolution significantly, i.e. both Doppler limited and Doppler free resolution could be achieved. To achieve these goals, we report our latest efforts in characterizing the tuning and noise properties of Quantum Cascade (QC) lasers; novel schemes on modulation to gain largest tuning range as well as...