A key parameter underlying the efficacy of any nonlinear optical process is group velocity dispersion. In quantum cascade lasers (QCLs), there have been several recent demonstrations of devices exploiting nonlinearities in both the mid-infrared and the terahertz. Though the gain of QCLs has been well studied, the dispersion has been much less investigated, and several questions remain about its...

The interfaces of a dielectric sample are resolved in reflection geometry using light from a frequency agile array of terahertz quantum-cascade lasers. The terahertz source is a 10-element linear array of third-order distributed-feedback QCLs emitting at discrete frequencies from 2.08 to 2.4 THz. Emission from the array is collimated and sent through a Michelson interferometer, with the sample ...

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters.

The present work reports on the first application of a ring-cavitysurface-emitting quantum-cascade laser (RCSE-QCL) for sensitive gas measurements. RCSE-QCLs are promising candidates for optical gassensing due to their single-mode, mode-hop-free and narrow-band emission characteristics along with their broad spectral coverage. The time resolved down-chirp of the RCSE-QCL in the 1227-1236 cm (8....

The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters. W continuous-wave room temperature single-facet emission from quantum cascade lasers based on nonresonant extraction design approach.

Silicon integration of mid-infrared (MIR) photonic devices promises to enable low-cost, compact sensing and detection capabilities that are compatible with existing silicon photonic and silicon electronic technologies. Heterogeneous integration by bonding III-V wafers to silicon waveguides has been employed previously to build integrated diode lasers for wavelengths from 1310 to 2010 nm. Recent...

We have measured the local lattice temperature distribution and modeled the heat transport in all classes of quantum cascade lasers operating both in the mid-infrared and terahertz ranges. All relevant active regions based on GaAs/AlGaAs, GaInAs/AlGaAsSb, GaInAs/AlInAs/InP material systems have been investigated. A common feature of such complex multiple heterostructures is the strong anisotrop...

The mid-infrared spectral region can be covered by quantum cascade (QC) semiconductor lasers, where the emission wavelength is tailored by bandstructure engineering. For a detailed review on QC lasers see Ref. [1]. Their emission energy is well below the band gaps of the hosting material system. Typical GaAs QC lasers operate in the mid-infrared regime with corresponding energies of ~100 meV, w...

The development of quantum dot cascade lasers has been proposed as a path to obtain terahertz semiconductor lasers that operate at room temperature. The expected benefit is due to the suppression of nonradiative electron-phonon scattering and reduced dephasing that accompanies discretization of the electronic energy spectrum. We present numerical modeling which predicts that simple scaling of c...

Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most pow...