Article
Physics, Applied
Nathalie Lander Gower, Shiran Levy, Silvia Piperno, Sadhvikas J. Addamane, John L. Reno, Asaf Albo
Summary: We conducted an experimental study on a new design for a terahertz quantum cascade laser (THz QCL) that combines two-well injector and direct-phonon scattering schemes. This design improves the performance of the lasers by using a direct phonon scattering scheme for depopulating the lower laser level and reducing the overlap with the doped region. The design also achieves efficient isolation of active laser levels and shows potential for higher operating temperatures than the current records.
APPLIED PHYSICS LETTERS
(2023)
Editorial Material
Nanoscience & Nanotechnology
Miriam S. Vitiello, Luigi Consolino, Massimo Inguscio, Paolo De Natale
Summary: QCL is the most powerful chip-scale source of optical frequency combs, allowing mode proliferation with large quantum efficiencies. THz QCL FCs have promising applications in various fields due to their high quantum efficiency and ease of integration.
Article
Physics, Applied
Li Wang, Tsung-Tse Lin, Mingxi Chen, Ke Wang, Hideki Hirayama
Summary: This study demonstrates the crucial role of compositional interdiffusion at interfaces in GaAs/AlGaAs alternating superlattices for developing high temperature terahertz quantum cascade lasers. By growing GaAs/Al0.3Ga0.7As superlattices using molecular beam epitaxy, an aluminum interdiffusion width of 0.95 nm is estimated. Incorporating this interdiffusion as a design parameter improves the maximum operating temperature of the laser by 20 K. The study also introduces an independent self-energy function based on axial correlation length to quantify the effects of interdiffusion scattering on electron dynamics.
APPLIED PHYSICS EXPRESS
(2023)
Article
Optics
Yuan-Yuan Li, Fang-Yuan Zhao, Yu Ma, Wei-Jiang Li, Jun-Qi Liu, Feng-Qi Liu, Jun-Wei Luo, Jin-Chuan Zhang, Shen-Qiang Zhai, Ning Zhuo, Li-Jun Wang, Shu-Man Liu
Summary: By integrating a suitable lens with a well-designed QCL array, multiple spatially-separated beams with controlled divergence angles and focusing efficiency are achieved. This method demonstrates excellent emission characteristics and multi-wavelength spectra at 77 K temperature.
OPTICS AND LASER TECHNOLOGY
(2021)
Article
Physics, Applied
M. Jaidl, N. Opacak, M. A. Kainz, D. Theiner, B. Limbacher, M. Beiser, M. Giparakis, A. M. Andrews, G. Strasser, B. Schwarz, J. Darmo, K. Unterrainer
Summary: This paper demonstrates terahertz quantum cascade lasers realized in ideal ring resonators without discontinuities, achieved by mounting the rings upside down on a silicon substrate using a die-bonding technique. The lasers emit light around 3.8 THz, show reduced threshold current densities, and exhibit frequency comb formation.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama
Summary: This study investigates the impact of parasitic absorption in the narrow module architecture with only two quantum wells, in the context of terahertz quantum cascade lasers utilizing the nonalignment injection scheme via direct-phonon resonance. The optical gain is found to be limited to small (or negative) values even at low temperatures. To address this issue, a strategy of suppressing parasitic absorption by increasing the injection energy is adopted, resulting in successful lasing at 194 K.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
Yunfei Xu, Yongqiang Sun, Weijiang LI, Yu Ma, Ning Zhuo, Junqi Liu, Jinchuan Zhang, Shenqiang Zhai, Shuman Liu, Lijun Wang, Fengqi Liu
Summary: This article reports on a phase-locked array scheme of terahertz quantum cascade laser (THz QCL) that utilizes Talbot effect. By adjusting the absorbing boundary width of each ridge in the array, stable operation and power amplification of THz QCL are achieved.
Review
Quantum Science & Technology
Miriam Serena Vitiello, Paolo De Natale
Summary: Quantum cascade lasers (QCLs) demonstrate the generation of artificial materials with tailor-made properties through quantum design, featuring intrinsic linewidths near the quantum limit and spontaneous phase-locking. Operating at terahertz frequencies, QCLs show important technological performances and have promising future prospects in the field of quantum technologies.
ADVANCED QUANTUM TECHNOLOGIES
(2022)
Article
Optics
Boyu Wen, Dayan Ban
Summary: This study proposes a potential and promising new quantum design scheme named the quasi one-well (Q1W) design for developing high-temperature terahertz quantum cascade lasers (QCLs). Simulation results using non-equilibrium green function and rate-equation models suggest that the Q1W design has the potential to achieve sufficient optical gain with low-temperature sensitivity.
Article
Physics, Applied
Ali Khalatpour, Man Chun Tam, Sadhvikas J. Addamane, John Reno, Zbignew Wasilewski, Qing Hu
Summary: In this paper, the maximum operating temperature of THz QCLs has been improved to approximately 261K, as a step toward the realization of compact semiconductor THz sources.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Luigi Consolino, Malik Nafa, Michele De Regis, Francesco Cappelli, Saverio Bartalini, Akio Ito, Masahiro Hitaka, Tatsuo Dougakiuchi, Tadataka Edamura, Paolo De Natale, Kazuue Fujita
Summary: This article presents the ultra-broadband THz emission obtained by intra-cavity mixing of different wavelengths, as well as the characterization and measurement methods of this emission. The new device can operate at low temperatures without the need for expensive liquid helium cooling, offering high stability and frequency accuracy.
APPLIED SCIENCES-BASEL
(2021)
Article
Optics
Ali Khalatpour, Andrew K. Paulsen, Chris Deimert, Zbig R. Wasilewski, Qing Hu
Summary: Terahertz frequencies are underutilized due to the lack of powerful and compact sources, but the invention of THz quantum cascade lasers has helped bridge this gap and expand potential applications. However, the technology is still limited by demanding cooling requirements, restricting its practical use outside of laboratory settings.
Article
Physics, Applied
P. Didier, O. Spitz, L. Cerutti, D. A. Diaz-Thomas, A. N. Baranov, M. Carras, F. Grillot
Summary: The experimental study focuses on the relative intensity noise of a multi-mode interband cascade laser at 4.1 micrometers, showing a relaxation frequency in the GHz range at room temperature. Results indicate that, above threshold current, relaxation frequency increases with bias current, with simulations matching experimental efforts. Fitting of relative intensity noise resonances provides insight into key parameters of the studied interband cascade laser.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Teppei Miyoshi, Hideki Hirayama
Summary: By implementing a relatively high impurity doping concentration, the output power of a GaAs-based terahertz quantum cascade laser was significantly enhanced.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Optics
Muhammad Anisuzzaman Talukder, Paul Dean, Edmund H. Linfield, A. Giles Davies
Summary: This study introduces a THz QCL heterostructure designed to emit two resonant photons from each electronic relaxation between two same-parity states, predicting a significant enhancement of light intensity compared to conventional THz QCL structures through simulations.
Article
Chemistry, Multidisciplinary
Alessandra Di Gaspare, Valentino Pistore, Elisa Riccardi, Eva A. A. Pogna, Harvey E. Beere, David A. Ritchie, Lianhe Li, Alexander Giles Davies, Edmund H. Linfield, Andrea C. Ferrari, Miriam S. Vitiello
Summary: This study demonstrates mode-locking in surface-emitting electrically pumped random quantum cascade lasers at terahertz frequencies by exploiting the giant third-order nonlinearity of semiconductor heterostructure lasers and the nonlinear properties of graphene. Self-induced phase-coherence between naturally incoherent random modes and phase-locked random modes are achieved using lithographically patterning a multilayer graphene film or coupling a saturable absorber graphene reflector. This milestone in the physics of disordered systems paves the way for miniaturized, electrically pumped mode-locked light sources for various applications.
Article
Chemistry, Multidisciplinary
Leonardo Viti, Elisa Riccardi, Harvey E. Beere, David A. Ritchie, Miriam S. Vitiello
Summary: The on-chip integration of two-dimensional nanomaterials with terahertz quantum cascade lasers has led to wide spectral tuning, nonlinear high-harmonic generation, and pulse generation. In this study, a large area multilayer graphene (MLG) was transferred to a THz QCL to monitor its local lattice temperature during operation. The MLG's temperature dependence of electrical resistance was used to measure the local heating of the QCL chip. The results were validated through photoluminescence experiments. This integrated system provides a fast temperature sensor for THz QCLs and enables full electrical and thermal control on laser operation.
Letter
Chemistry, Multidisciplinary
Daisy Q. Wang, Zeb Krix, Oleg P. Sushkov, Ian Farrer, David A. . Ritchie, Alexander R. . Hamilton, Oleh Klochan
Summary: By imposing an external periodic electrostatic potential, the electronic properties of the confined electrons in a quantum well can be different from those in the host semiconductor. In this study, we fabricated and investigated a tunable triangular artificial lattice on a GaAs/AlGaAs heterostructure, where the band structure and Fermi surface can be transformed by altering a gate bias. Magnetotransport measurements revealed multiple quantum oscillations and commensurability oscillations due to electron scattering from the artificial lattice. Increasing the modulation strength revealed new commensurability oscillations caused by electron scattering from the artificial Fermi surface and triangular lattice. These results demonstrate the ability to form artificial two-dimensional crystals with designer electronic properties using low disorder gate-tunable lateral superlattices.
Article
Nanoscience & Nanotechnology
J. D. Fletcher, W. Park, S. Ryu, P. See, J. P. Griffiths, G. A. C. Jones, I. Farrer, D. A. Ritchie, H. -s. Sim, M. Kataoka
Summary: Coulomb forces between high-energy electrons in unscreened regime are detected and analysed using a mesoscopic electron collider. The ability to control Coulomb interactions on picosecond time scales is crucial for quantum logic devices with flying electrons. Despite previous findings, our study reveals Coulomb-dominated collisions of high-energy single electrons in counter-propagating ballistic edge states, indicating new ways to utilize Coulomb interactions for high-speed sensing or gate operations on flying electron qubits.
NATURE NANOTECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
C. P. Dobney, A. Nasir, P. See, C. J. B. Ford, J. P. Griffiths, C. Chen, D. A. Ritchie, M. Kataoka
Summary: We have fabricated a device with two lateral p-n junctions on an n-type GaAs/Al0.33Ga0.67As heterostructure. The n-type material was converted to p-type by removing dopants and applying a voltage to a gate in this region. Controlled electroluminescence from both p-n junctions was demonstrated by varying the applied bias voltages. The emitted spectrum peak width was approximately 8 units.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Applied
L. Liu, Y. Gul, S. N. Holmes, C. Chen, I. Farrer, D. A. Ritchie, M. Pepper
Summary: In this study, we systematically investigate a structure found in In0.75Ga0.25As heterostructures, and observe its stability and anisotropy in high magnetic fields. This research is important for understanding low-dimensional electronic systems with strong spin-orbit coupling.
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Abdullah M. Zaman, Yuezhen Lu, Nikita W. Almond, Oliver J. Burton, Jack Alexander-Webber, Stephan Hofmann, Thomas Mitchell, Jonathan D. P. Griffiths, Harvey E. Beere, David A. Ritchie, Riccardo Degl'Innocenti
Summary: The study investigates the polarization modulation performance of an integrated metamaterial/graphene device in the THz band. By modifying the graphene's Fermi level, the device's optical response can be modified, enabling active tuning of ellipticity and continuous modification of optical activity. Active circular dichroism and optical activity can be independently exploited by carefully selecting the transmitted frequency and relative angle between the incoming linear polarization and the device's symmetry axis. This all-electronically tuneable versatile polarization device has potential applications in polarization spectroscopy, imaging, and THz wireless generation.
FRONTIERS IN NANOTECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
P. M. T. Vianez, Y. Jin, W. K. Tan, Q. Liu, J. P. Griffiths, I. Farrer, D. A. Ritchie, O. Tsyplyatyev, C. J. B. Ford
Summary: Determining the bare electron mass (m0) in crystals is challenging due to many-body effects. By using a one-dimensional geometry, the interaction effects can be separated from m0, and the measured value is (0.0525 +/- 0.0015)me in GaAs. The value of m0 remains constant with varying density, and it is approximately 22% lighter than observed in higher-dimensional GaAs structures, consistent with the quasiparticle picture of a Fermi liquid.
Article
Materials Science, Multidisciplinary
M. J. Rendell, S. D. Liles, A. Srinivasan, O. Klochan, I. Farrer, D. A. Ritchie, A. R. Hamilton
Summary: In two-dimensional systems with a spin-orbit interaction, magnetic focusing is utilized to separate particles with different spins spatially. We conducted measurements on hole magnetic focusing under two different magnitudes of the Rashba spin-orbit interaction. We discovered that the attenuation of a focusing peak, conventionally linked to a change in spin polarization, is actually caused by a change in the scattering of a spin state in hole systems with a k3 spin-orbit interaction. Additionally, we found that the change in scattering length determined through magnetic focusing is consistent with the results obtained from Shubnikov-de Haas oscillations measurements.
Proceedings Paper
Engineering, Electrical & Electronic
J. Holstein, M. Horbury, N. North, H. Godden, A. Krysl, A. Lisauskas, L. H. Li, A. Valavanis, J. R. Freeman, E. H. Linfield, H. G. Roskosl
Summary: Researchers propose a new design for a terahertz detector, using a matrix of 8x8 monolithically integrated patch-antenna-coupled TeraFETs as the pixels and combining the output signals of all elements in a parallel read-out circuit. This design offers a larger effective detector area, easier beam alignment, and reduced resistance, leading to reduced noise and improved time resolution in measurements of dynamic processes.
2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
M. D. Horbury, N. K. North, J. Holstein, H. Godden, L. H. Li, J. R. Freeman, E. H. Linfield, H. Roskos, A. Lisauskas, A. Valavanis
Summary: Here, we have demonstrated the potential of using terahertz (THz) spectroscopy to probe chemical reactions by observing distinct transitions in methanol and deuterated methanol (CH3OD) in specific THz frequency regions.
2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
C. Kidd, M. C. Rosamond, T. B. Gill, L. H. Li, E. H. Linfield, A. G. Davies, J. R. Freeman
Summary: An improved large area design has been developed for LT-GaAs photoconductive antenna arrays on sapphire substrates, resulting in higher field terahertz radiation.
2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
N. K. North, J. Holstein, M. D. Horbury, H. Godden, L. H. Li, J. R. Freeman, E. H. Linfield, H. Roskos, A. Lisauskas, A. Valavanis
Summary: This study demonstrates real-time analysis of the emission from a 3.4-THz quantum-cascade laser using an array of nanoscale field-effect transistor devices. The results show that THz power can be directly detected up to a modulation bandwidth of 500 kHz, and indirectly through a change in the device threshold up to a bandwidth of 100 MHz.
2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
M. Salih, S. S. Kondawar, N. Brewster, L. H. Li, E. H. Linfield, H. Wang, P. G. Huggard, J. R. Freeman, D. Gerber, A. Valavanis
Summary: This study demonstrates the integration of a 2.1-THz quantum cascade laser into an IEEE standard rectangular metallic waveguide for the first time, resulting in single-mode continuous-wave laser emission.
2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
T. B. Gill, A. D. Burnett, C. Towler, C. Kidd, A. Dunn, L. Li, J. R. Freeman, E. H. Linfieldl, A. G. Davies, P. Dean
Summary: High field terahertz spectroscopy measurements demonstrate that the features of lactose monohydrate at certain frequencies saturate with increasing THz field strength, indicating the potential of dynamically distorting the crystal structure at sufficiently high fields.
2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ
(2023)
