A5089135298- Semiconductor Lasers and Optical Devices
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Point processes and geometric inequalities
- Probability and Risk Models
- Terahertz technology and applications
- Simulation Techniques and Applications
- Markov Chains and Monte Carlo Methods
- Advanced Fiber Laser Technologies
- Bayesian Methods and Mixture Models
- Stochastic processes and statistical mechanics
- Statistical Distribution Estimation and Applications
- Laser Design and Applications
- Advanced Queuing Theory Analysis
- Mathematical Approximation and Integration
- Probabilistic and Robust Engineering Design
- Semiconductor Quantum Structures and Devices
- Diffusion and Search Dynamics
- Scientific Research and Discoveries
- Transportation Planning and Optimization
- Optical Coherence Tomography Applications
- Financial Risk and Volatility Modeling
- Insurance, Mortality, Demography, Risk Management
- Analytical Chemistry and Sensors
- Neural Networks and Applications
The University of Queensland
2016-2025
The University of Melbourne
2021
Harvard University Press
2021
Queensland University of Technology
2015-2016
Eindhoven University of Technology
2016
University of Amsterdam
2015-2016
Sheffield Hallam University
2015
University of Leeds
2015
This tutorial presents a guided tour of laser feedback interferometry, from its origin and early development through implementation to slew sensing applications, including displacement, distance, velocity, flow, refractive index, linewidth measurement. Along the way, we provide step-by-step derivation basic rate equations for experiencing optical starting standard Lang Kobayashi model detail their subsequent reduction in steady state excess-phase equation. We construct simple framework...
The terahertz (THz) frequency quantum cascade laser (QCL) is a compact source of THz radiation offering high power, spectral purity and moderate tunability. As such, these sources are particularly suited to the application imaging across range disciplines, have motivated significant research interest in this area over past decade. In paper we review technological approaches QCL-based key advancements within field. We discuss detail number targeted areas including multiple-frequency...
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 spontaneously generate combs.
The terahertz (THz) frequency quantum cascade laser (QCL) is a compact source of high-power radiation with narrow intrinsic linewidth. As such, THz QCLs are extremely promising sources for applications including high-resolution spectroscopy, heterodyne detection, and coherent imaging. We exploit the remarkable phase-stability to create swept-frequency delayed self-homodyning method both imaging materials analysis, using feedback interferometry. Using our scheme we obtain amplitude-like...
Quantum cascade lasers (QCLs) are high-power sources of coherent radiation in the midinfrared and terahertz (THz) bands. Laser feedback interferometry (LFI) is one simplest techniques, for which emission source can also play role a highly-sensitive detector. The combination QCLs LFI particularly attractive sensing applications, notably THz band where it provides high-speed high-sensitivity detection mechanism inherently suppresses unwanted background radiation. with has been demonstrated...
This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results several pressure distributions including those progressive waves, standing well diffraction interference patterns waves. The proposed solution has distinct advantage extreme simplicity robustness thus opening way to low cost field system based on mass produced laser diodes.
Self-mixing laser sensors show promise for a wide range of sensing applications, including displacement, velocimetry, and fluid flow measurements. Several techniques have been developed to simulate self-mixing signals; however, complete succinct process synthesizing signals has so far absent in the open literature. This article provides systematic numerical approach analysis using steady-state solution Lang Kobayashi model. Examples are given how this method can be used synthesize arbitrary...
We demonstrate coherent terahertz (THz) frequency imaging using the self-mixing effect in a quantum cascade laser (QCL). Self-mixing voltage waveforms are acquired at each pixel of two-dimensional image etched GaAs structures and fitted to three-mirror model, enabling extraction amplitude phase parameters reflected field. From phase, we reconstruct depth sample surface, show that can be related reflectance. Our approach is experimentally simple compact, does not require stabilization THz QCL.
There is considerable interest in the interrogation of biological tissue at terahertz (THz) frequencies, largely due to contrast optical properties different tissues which occur this electro-magnetic radiation band. Of particular are THz biomedical images, have potential highlight information than those acquired other frequency bands, thereby providing an augmented picture structures. In work, we demonstrate feasibility interferometric imaging technique using a quantum cascade laser (QCL)...
We report a coherent terahertz (THz) imaging system that utilises quantum cascade laser (QCL) operating in pulsed-mode as both the source and detector. The realisation of short-pulsed THz QCL feedback interferometer permits high peak powers improved thermal efficiency, which enables cryogen-free operation system. In this work, we demonstrated swept-frequency interferometry experimentally. Our interferometric detection scheme not only simultaneous creation amplitude phase images, but...
Early detection of skin pathologies with current clinical diagnostic tools is challenging, particularly when there are no visible colour changes or morphological cues present on the skin. In this study, we a terahertz (THz) imaging technology based narrow band quantum cascade laser (QCL) at 2.8 THz for human pathology diffraction limited spatial resolution. was conducted three different groups unstained samples (benign naevus, dysplastic and melanoma) compared to corresponding traditional...
Quasi-static interferometric signals in lasers under feedback arise from slowly varying perturbations of the intracavity electric field resulting reinjection a portion emitted into cavity. Such are well described by steady-state solution to Lang-Kobayashi rate equation model. We give an exact series expansion for this that shows precisely how Acket's characteristic parameter C and Henry's linewidth enhancement factor α influence such signals. show coefficients can be extracted easily explain...
We demonstrate coherent three-dimensional terahertz imaging by frequency modulation of a quantum cascade laser in compact and experimentally simple self-mixing scheme. Through this approach, we can realize significantly faster acquisition rates compared to previous schemes employing longitudinal mechanical scanning sample. achieve depth resolution better than 0.1 μm with power noise spectral density below -50 dB/Hz, for sampling time 10 ms/pixel.
The cross-entropy and minimum methods are well-known Monte Carlo simulation techniques for rare-event probability estimation optimization. In this paper, we investigate how these can be eXtended to provide a general non-parametric framework based on φ-divergence distance measures. We show the χ 2 distance, in particular, yields viable alternative Kullback—Leibler distance. theory is illustrated with various eXamples from density estimation, continuous multi-eXtremal
Terahertz-frequency quantum cascade lasers (THz QCLs) based on bound-to-continuum active regions are difficult to model owing their large number of states. We present a computationally efficient reduced rate equation (RE) that reproduces the experimentally observed variation THz power with respect drive current and heat-sink temperature. also dynamic (time-domain) simulations under range currents predict an increase in modulation bandwidth as approaches peak light–current curve, mid-infrared...
We propose a self-consistent method for the analysis of granular materials at terahertz (THz) frequencies using quantum cascade laser. The is designed signals acquired from laser feedback interferometer, and applied to non-contact reflection-mode sensing. Our technique demonstrated three plastic explosives, achieving good agreement with reference measurements obtained by THz time-domain spectroscopy in transmission geometry. described this study readily scalable: replacing single small...
We provide an experimental evidence of transient instabilities (TIs) in a terahertz (THz) quantum cascade laser (QCL) under optical feedback, contrast to the widely accepted claim that THz QCLs are ultrastable against feedback. The TIs appear as periodic oscillations emitted power or terminal voltage with increasing oscillation frequency feedback increases. absence relaxation and low linewidth enhancement factor makes them platform uniquely suitable for exploring external-cavity-related...