We report a coherent terahertz (THz) imaging system that utilises a quantum cascade laser (QCL) operating in pulsed-mode as both the source and detector. The realisation of a short-pulsed THz QCL feedback interferometer permits both high peak powers and improved thermal efficiency, which enables the cryogen-free operation of the system. In this work, we demonstrated pulsed-mode swept-frequency laser feedback interferometry experimentally. Our interferometric detection scheme not only permits the simultaneous creation of both amplitude and phase images, but inherently suppresses unwanted background radiation. We demonstrate that the proposed system utilising microsecond pulses has the potential to achieve 0.25 mega-pixel per second acquisition rates, paving the pathway to video frame rate THz imaging.
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http://dx.doi.org/10.1364/OE.27.010221 | DOI Listing |
Phys Rev Lett
December 2024
Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom.
Many experimental platforms for quantum science depend on state control via laser fields. Frequently, however, the control fidelity is limited by optical phase noise. This is exacerbated in stabilized laser systems where high-frequency phase noise is an unavoidable consequence of feedback.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal and INESC TEC, Centre of Applied Photonics, Rua do Campo Alegre 687, 4169-007 Porto, Portugal.
Easily accessible through tabletop experiments, paraxial fluids of light are emerging as promising platforms for the simulation and exploration of quantumlike phenomena. In particular, the analogy builds on a formal equivalence between the governing model for a Bose-Einstein condensate under the mean-field approximation and the model of laser propagation inside nonlinear optical media under the paraxial approximation. Yet, the fact that the role of time is played by the propagation distance in the analog system imposes strong bounds on the range of accessible phenomena due to the limited length of the nonlinear medium.
View Article and Find Full Text PDFJ Neurosci
January 2025
Laboratory of Reproductive Neurobiology, Hun-Ren Institute of Experimental Medicine, Budapest, 1083 Hungary;
While hypothalamic kisspeptin (KP) neurons play well-established roles in the estrogen-dependent regulation of reproduction, little is known about extrahypothalamic KP-producing (KP) neurons of the lateral septum. As established previously, expression in this region is low and regulated by estrogen receptor- and GABA receptor-dependent mechanisms. Our present experiments on knock-in mice revealed that transgene expression in the LS begins at P33-36 in females and P40-45 in males and is stimulated by estrogen receptor signaling.
View Article and Find Full Text PDFCascaded Raman fiber lasers (CRFLs) with wavelength-independent feedback can provide power at any wavelength in near-IR regions. However, broad feedback leads to a broad output spectrum, decreasing spectral power density at a desired wavelength. The output characteristics of CRFLs can be controlled by controlling the feedback.
View Article and Find Full Text PDFWe experimentally demonstrate a cost-effective dual-polarization quadrature phase shift keying (DP-QPSK) coherent passive optical network (PON) system that operates at 100 Gbits/s/λ. This system utilizes distributed feedback lasers (DFBs) and a carrier recovery algorithm facilitated by a bifunctional frequency-domain pilot tone (FPT). To reduce costs in coherent PON implementations, low-cost DFBs are employed as the sole light sources, replacing the more expensive external cavity lasers (ECLs) at both the optical line terminal (OLT) and the optical network units (ONUs).
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