Broadband Distributed-Feedback Quantum Cascade Laser Array Operating From 8.0 to 9.8 $\mu$m

Abstract

Abstract-An ultra-broadband distributed-feedback quantum cascade laser array was fabricated, using a heterogeneous cascade based on two bound-to-continuum designs centered at 8.4 and 9.6 m. This array emitted in a range over 220 cm 1 near a 9-m wavelength, operated in pulsed mode at room temperature. The output power of the array varied between 100-and 1100-mW peak intensity.Index Terms-Distributed-feedback (DFB) lasers, infrared spectroscopy, mid-infrared, quantum cascade lasers (QCLs), semiconductor lasers.

Broadly tunable terahertz generation in mid-infrared quantum cascade lasers

“…Cherenkov DFG scheme allows for efficient extraction of THz radiation along the whole length of the QCL waveguide at any THz frequency 12 . As mid-infrared frequencies in a QCL can be tuned well over 5 THz 15,16 and optical non-linearity for intracavity THz DFG is not expected to change significantly over several THz of tuning 17 , Cherenkov DFG-QCLs are uniquely suited to be operated as broadly tunable THz sources for applications such as spectroscopy, microscopy and drug or explosives detection.…”

“…An alternative approach to generate THz radiation in QCLs are sources based on intracavity difference-frequency generation (DFG) in dual-wavelength mid-infrared (l ¼ 3-15 mm) QCLs designed to have giant optical non-linearity in the active region [10][11][12][13][14] . Not only can these sources operate at room temperature [11][12][13][14] , but they are also uniquely suited to provide THz output over a wide range of frequencies, as the mid-infrared frequencies in a QCL can be tuned well over 5 THz 15,16 and the optical non-linearity for intracavity THz DFG is not expected to change significantly over several THz of tuning 17 . The current challenge that must be addressed is their limited THz power output due to low mid-infrared-to-THz conversion efficiency.…”

Broadly tunable monolithic room-temperature terahertz quantum cascade laser sources

“…Recent demonstrations of monolithic single-mode mid-IR QCL tuners based on sampled gratings with over 230 cm À 1 (nearly 7 THz) tuning range 37 indicate that future monolithic THz DFG-QCL sources may achieve spectral coverage of the entire 1-6 THz frequency window and beyond. The devices reported here may also be integrated into arrays of lasers, similarly to that demonstrated in mid-IR 38 , to provide continuous spectral coverage over a broad THz spectral range.…”

High-performance midinfrared quantum cascade lasers

“…The tuning range of this source was recently increased to 220 cm −1 using a 24-laser array. 24 Tunability over a much broader range than what a typical DFB QCL can offer is a highly desirable feature for trace gas analysis, for it enables the parallel detection of multiple chemicals and allows mapping of very broad absorption lines, such as those of liquids. In this section we analyze the most effective device design strategies to achieve such a goal.…”

“…In recent work, 24 the range of frequencies covered by a single DFB QC laser spectrometer was greatly increased to cover the available gain spectrum. The emission spectrum of the array (Fig.…”