Regenerative similariton laser

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Non-ablative femtosecond laser processing of transparent substrates involves cumulative, multi-timescale dynamics that hinder precise control of induced structural modifications. Here, we demonstrate a feedback-compatible diagnostic based on mid-infrared transmission monitoring using a continuous-wave QCL emitting at 4.46 µm. This approach enables in situ observation of structural dynamics induced by femtosecond laser irradiation at repetition rates up to 250 kHz. The technique shows sensitivity to key tran

We demonstrate high-resolution in situ imaging of density-wave ordering induced by cavity-mediated interactions in a unitary Fermi gas. We observe long-range spatial correlations throughout the formation of density waves, both for adiabatic preparation and following a quench, with a pattern controlled by the cavity mode structure. Our single-shot microscopic images together with the real-time readout of the cavity photons provide access to atom-photon correlations. We use this capability to investigate orde

Wavelength‐tunable pulsed lasers have garnered significant research interest due to their critical role in applications requiring precise spectral matching, such as wavelength‐division multiplexing and spectroscopic analysis. Although recent hybrid architectures integrating saturable absorbers with wavelength‐selective components have enabled notable progress, these systems remain constrained by two fundamental challenges: excessive coupling losses and complex alignment procedures. Here, a compact wavelengt

Femtosecond laser offers a means to confine energy beyond the diffraction limit. Applied to glass, this high energy confinement leads to intriguing modification of the glass structure, inducing a variety of events such as nano-crystallization, amorphization or phase separation. Here, we review these structural modifications, their observations as well as means to control it and one can achieve nanoscale confinement along the laser propagation axis. Furthermore, we discuss how they can be used in the context

Purpose – Since pulsed lasers are mainly used in selective laser sintering (SLS) – contrarily to selective laser melting (SLM) – only the exterior of the powder particles is molten while their core stays solid. The purpose of this paper is to investigate the binding mechanism between two particles of titanium powder. Design/methodology/approach – A dedicated experimental setup is used to isolate the particles. They are then irradiated by the laser. SEM micrographs are taken at each step and image analysis i

Nanoparticles are interesting for biomedical imaging as novel non- fluorescent non-bleaching labels. We present the characterization of freely diffusing nanoparticles using third harmonic generation correlation spectroscopy by illumination with a focussed pulsed femtosecond laser. We present the optical system as well as first spectroscopic results on nanoparticles.

Quantitative phase images make digital holographic microscopy (DHM) an excellent instrument for metrological, but also for biological applications, where it can reveal deformations and morphological details at ultrahigh resolution in the order of a few nanometers only, while also precisely determining the refractive index across a sample (e.g. cell or neuron). On the other hand, non-linear light-matter interactions have also proved very useful in microscopy. For instance, second harmonic generation (SHG) al

We report direct absorption spectroscopic detection of ozone at ambient pressure with a pulsed, DFB quantum-cascade laser (QCL) tuned within 1044-1050 cm(-1) by temperature scanning. Wavelength calibration curves were derived from FTIR and CO2 spectra and interpreted with respect to the heat transfer from the heterostructure to the sink. The laser linewidth (similar to0.13 cm(-1) FWHM) was found to decrease with temperature, probably as a result of operation at constant current. Spurious spectral features d

A 3D imager is presented capable of computing the depth map as well as the intensity scale of a given scene. The heart of the system is a two-dimensional array of single photon avalanche diodes fabricated in standard CMOS technology. The diodes exhibit low noise equivalent power, high dynamic range and superior linearity. The 3D imager achieves sub-millimetric precision at depth-of-field of a few meters. It operates using a standard LASER source pulsed at 50MHz with 40mW peak power and requires no mechanica

Over the past decade a new family of optoelectronic devices has emerged whose performance is enhanced by placing the active device structure inside a Fabry–Perot resonantmicrocavity [P. E. Green, IEEE Spectrum 13 (2002)]. The increased optical field allows photodetectors to be made thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. We have demonstrated a variety of resonant cavity enhanced (RCE) photodetectors in compound semiconductors [B. Yang

First results and analysis of second harmonic generation with a Nd:YAG laser working in the long pulse, free running mode are presented in this paper. Second harmonic generation conversion efficiencies of up to 17.5% and pulse powers of 162W have been generated with a free running Nd:YAG laser and a KTP non-linear crystal. The conversion efficiency is limited by a saturation effect and optical damage occurring at similar to50 times lower peak intensities than in the Q-switch mode. The saturation and damage

We propose in this paper a novel method for generating the pump and probe signals for a Brillouin fibre sensor. It is based on the injection locking of two distinct semiconductor lasers, that makes possible the generation of high purity beat signals in the microwave frequency range. Such a technique can be used either in the pulsed pump-probe technique or the new correlation-based technique. Furthermore novel devices, such as laser modules presenting integrated electro-absorption modulators, can be exploite

Excimer Laser Ablation is a micro-machining method which has undergone an important breakthrough in the last twenty years. In contrast with most literature studies, dealing with Static Ablation, this PhD work focuses on the study of Scanning Ablation of poly(ethylene terephthalate) (PET) at 193 nm, using relatively high fluences of about 1 J/cm2. Here, Static Ablation means that the substrate is fixed with respect to the laser beam. In this way, the size of the machined area per set of pulses does not excee

An all-fiber phase-modulated master oscillator power amplifier for free-space coherent communication is presented. A distributed-feedback fiber laser at 1.06 μm is used as master oscillator. A novel phase modulator based on a ZnO-coated single-mode fiber modulates the single frequency communication signal. The modulated signal is then amplified in a double-clad doped fiber power amplifier. Up to 1 W cw single-frequency output power, phase modulated at 196 MHz, has been obtained.

For future divertor studies on TCV measurements of electron temperature and density and their spatial gradients along open flux surfaces will be of major interest. A Thomson scattering system is proposed for this purpose, which takes advantage of the good access via horizontal ports on three vertical levels. The modular design of the existing Thomson scattering diagnostic on TCV offers the possibility to modify it for simultaneous measurements in the main plasma and in the divertor region using the same las

Photoluminescence intensity and emission wavelength of InAsP/InGaAsP and InGaAs/InGaAsP multi-quantum well (MQW) laser structures grown by chemical beam epitaxy (CBE) at 460 degrees C and V/III ratio of 2 are considerably affected by annealing at temperatures 600-650 degrees C which prevents lasing of these structures fused on GaAs substrates. It is shown that the degradation of luminescence characteristics can be decreased by increasing the growth temperature to 480 degrees C and V/III ratio to 4. InAsP/In

We report on studies of extended defects in electron-beam-pumped Zn1-xCdxSe/ZnSe blue and blue-green laser structures. To establish a direct correlation between the local luminescence properties and the presence of structural defects, the same thin foil samples were sequentially examined by transmission electron microscopy (TEM) and cathodoluminescence (CL) microscopy. The majority of the non-radiative defects were found to have one or more threading dislocations in their vicinity. Stacking faults, as a rul

Degradation defects induced by electron-beam bombardment in Zn1-xCdxSe/ZnSe (001) graded-index separate-confinement blue-green laser structures have been characterized by transmission electron microscopy. Most defects appear as tree-like arrangements of small extrinsic and intrinsic dislocation loops opening in +/-[100] or +/-[010] directions and are located within the quantum well or at its boundaries. The Burgers vectors of the loops were identified as b = 1/2[01(1) over bar] and b = 1/2[10(1) over bar] f

A 2 + 1 double-resonance laser-induced fluorescence technique is described in which the high power of a pulsed laser is combined with the narrow bandwidth of a single-mode cw ring dye laser. The combination of these laser systems allows the study of highly excited states with MHz resolution. This double-resonance technique has been applied to the study of the B-1 Sigma(+)(upsilon' = 0)

We have recently shown that in II-VI/III-V heterojunctions and related devices fabricated by molecular beam epitaxy, the II/VI flux ratio employed during the early stages of II-VI growth can be used to control the local interface composition and the band alignment. Here we demonstrate that the local interface composition in pseudomorphic, strained ZnSe/GaAs(001) heterostructures as well as lattice-matched ZnSe/In0.04Ga0.96As(001) heterostructures also have a dramatic effect on the nucleation of native stack

Regenerative similariton laser

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Laser-based in situ monitoring of femtosecond-laser in-bulk processing of glass

Microscopy of Cavity-Induced Density-Wave Ordering in Ultracold Gases

Wavelength Tunable Pulsed Lasers Enabled by a Versatile Metafiber Functioning as Both Saturable Absorber and Filter

Functional integration through femtosecond laser-induced nano-structuration of glass

Study of the inter-particle necks in selective laser sintering

Characterization of Nanoparticles Using Non-linear Correlation Spectroscopy

Digital holography for second harmonic microscopy

Ozone detection by differential absorption spectroscopy at ambient pressure with a 9.6 mu m pulsed quantum-cascade laser

Toward a 3-D Camera Based on Single Photon Avalanche Diodes

High-speed Si resonant cavity enhanced photodetectors and arrays

Second harmonic generation with free running Nd : YAG laser

2-laser injection-locking configuration for Brillouin fibre sensors

Scanning excimer laser ablation of poly(ethylene terephthalate) (PET) and its application to rapid prototyping of channels for microfluidics

All-fiber phase-modulated master oscillator power amplifier for coherent communication

A Thomson scattering diagnostic for measurements in the divertor region of TCV

Thermal Stability of InP-Based Structures for Wafer Fused Laser Diodes

Transmission electron microscopy and cathodoluminescence studies of extended defects in electron-beam-pumped Zn1-xCdxSe/ZnSe blue-green lasers

Degradation defects in electron-beam-pumped Zn1-xCdxSe/ZnSe graded-index separate-confinement heterostructure (GRINSCH) blue and blue-green lasers

High resolution pulsed-cw double-resonance spectroscopy on the B-1 Sigma(+)(v'=0)

Local interface composition and extended defect density in ZnSe/GaAs(001) and ZnSe/In0.04Ga0.96As(001) heterojunctions