The dual wavelength Bi-vertical cavity surface-emitting laser

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High-speed atomic force microscopy enables real-time visualization of molecular dynamics using small cantilevers with high resonance frequencies. To further enhance temporal resolution, cantilevers must be scaled down to achieve higher resonance frequencies while maintaining low spring constants to minimize tip-sample interaction forces and preserve sample integrity. As cantilevers shrink, conventional piezo-based actuation, relying on external actuators to drive the cantilever, becomes less effective due t

A novel concept for distributed fiber sensing has recently been introduced, in which the sensing fiber itself forms a laser cavity. This configuration yields a high-quality response that is largely independent of position, thereby enhancing measurement accuracy and acquisition speed, and opening new avenues towards higher-performance sensing technologies.

The engineering of aluminum nitride (AlN) waveguides allows for broad supercontinuum generation (SCG) within its wide transparency window (200 nm - 5.5 μm) enabling applications in precision spectroscopy and metrology fields. An efficient coverage from 500 to 3500 nm was shown by pumping crystalline AlN waveguides with a femtosecond laser centered at 1560 nm [1]. UV and visible coverage was reached by pumping around 800 nm and by chirping the waveguide [2] or by exploiting the modal dispersion of higher-ord

Lately, the use of ultrafast in-volume laser-based processing of transparent materials has gained ground as a 3D-printing method of functional materials, photonics devices and high-density storage media. In this talk, we discuss the use of wide-field third-harmonic imaging that offers a non-destructive means for investigating and characterizing laser-written in-volume complex structures. Specifically, the method is used for identifying laser-induced modifications and establishing their taxonomy over a large

With the rising need for microfabricated chip-scale atomic clocks to enable high precision timekeeping in portable applications, there has been active interest in developing miniature (

The aim of this project is to study the use of pulsed infrared laser light to stimulate the central auditory system. This novel approach may be a means to improve the efficacy of the current generation of electrically based Auditory Brainstem Implants (ABI). Infrared neural stimulation (INS) has been shown to activate peripheral nerves and other excitable cells. This method appears to achieve a stimulation that is more spatially selective than traditional electrical methods. In this project, the use of INS

We report on the micro-fabrication and characterization of a chip-scale plasma light source based on a Rubidium (Rb) vapor cell. The Rb plasma light source is intended for use as an integrated optical pump-light source in miniature double-resonance Rb atomic clocks [1, 5]. The RF plasma is capacitively coupled using external electrodes, and the light source is impedance matched to the source for frequencies between 1 and 36 MHz. Rb vapor cells have been previously developed as reference cells for atomic clo

Fibers doped with bismuth show broad luminescence bands around 750, 1100, and 1400 nm with spectral bandwidths of 100 to 200 nm at room temperature. The luminescence bands can be observed by pumping broad absorption bands in the visible or near infrared spectrum (around 500, 700, 800, 1000, and 1360 nm). Bismuth fiber laser action has been demonstrated using FBG in standard germanosilicate fibers as intra-core laser mirrors. In this work we report about the investigation of refractive index and luminescence

We demonstrate 2-mu m wavelength, wafer-fused InGa(Al)As/InP-AlGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting single-mode power of 0.5 mW at room-temperature with a threshold current of 4mA and side-mode suppression ratio of over 30 dB. Emission wavelength can be continuously tuned with current by similar to 5 nm without mode hopping with a tuning rate of 0.31 nm/mA. These features demonstrate the long wavelength VCSELs potential for gas sensing and other optical spectroscopy applicatio

An ammonia traces analyser based on photoacoustic spectroscopy is described. The system uses a CO2 laser and a properly designed resonant photoacoustic cell to achieve ammonia detection at sub-parts-per- billion (ppb) level. The instrument features unattended automatic on-line monitoring of ammonia with a detection limit of 0.1 ppb. Interferences from atmospheric CO2 and H2O are efficiently suppressed by a careful selection of the laser wavelength and a compensation of the water vapour signal made with a hi

Spatially resolved photoluminescence spectra of thin GaAs quantum wells are measured by near-field spectroscopy, and two-energy autocorrelation functions of the spectra are derived. We demonstrate distinctly different autocorrelation functions for a 3-nm-thick quantum well grown on a (311)A surface and for quantum wells grown on (100) substrates. The autocorrelation spectra of the (311)A GaAs quantum well are quantitatively described by a statistical disorder model with a single correlation length of 17 nm

A new nondestructive method for measuring the spatial distribution of chromatic dispersion along an optical fiber is presented. It is based on using Brillouin optical time-domain analysis to probe the power distribution of the four-wave mixing generated by two continuous-wave lasers. The results obtained prove that this new method is capable of providing better performance than comparable techniques. Furthermore, sensing the variations of Brillouin gain maximum produces additional information about the fibe

Attachment-induced ionization instability has been experimentally observed in O-2 and CF4 capacitive RF discharges using time-resolved voltage probe, Langmuir probe, optical emission and mass spectrometry measurements. This instability occurs under specific conditions of power and pressure, and produces synchronized oscillations in the kilohertz range on potentials, emission intensity and positive ion fluxes. In contrast, the SF6 plasma was observed to remain stable under all experimental conditions. This c

Microcavity exciton polaritons, the fundamental optical excitations of semiconductor microcavities with quantum wells inside, have been proposed as promising candidates for observing stimulated scattering, condensation and other phenomena related to the bosonic nature of excitons. Having a light mass, quantum degeneracy of polaritons can be reached at low densities and high temperatures. But the radiative time of polaritons is very short (in the picosecond range) and usually prevents an efficient thermaliza

Exciton states in semiconductor nanostructures with disorder exhibit level repulsion, a concept known from random matrix theory. Its manifestations in time-resolved Rayleigh spectra and in the autocorrelation of optical nearfield spectra are explained, and available experimental results are critically discussed. It is proposed to investigate the intrasubband absorption in quantum wells with emphasis on the aspects of level repulsion. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An optical modulator is arranged to compensate for the thermo-optical modulating effects induced by charge-injection based phase modulators. It comprises first modulator means (3), that receive optical radiation (11, 21), direct it along an optical path, apply a first predetermined optical phase modulation by the injection of free charges into the optical path, and output optical radiation (13, 22) so modulated. Compensator means (4) apply, to optical radiation output from (13, 22), or to be received by, th

We study the subpicosecond gain dynamics in a high-finesse semiconductor microcavity containing quantum wells by means of degenerate pump-probe spectroscopy. Tuning the optical excitation in resonance with both the exciton and the cavity modes, at high pump fields the probe pulses are strongly amplified near the energy of the empty-cavity mode. At zero probe delay, integration of the probe spectrum yields a net gain of several percents. The coherent nature of the gain is demonstrated by its oscillatory beha

Diode-pumped solid body laser comprises an acoustic-optical modulator, a laser crystal, a delay plate and a crystal that doubles the frequency of the laser beam. Pulse lengthening is carried out by internal coupling of a doubler mechanism within the laser resonator Preferred Features: The end surface of the laser crystal is formed as an end mirror limiting the laser resonator. The mirror is highly reflective for the laser beam. Crystals of SiO2 or TeO2 are provided for the acoustic-optical modulator.

Photoluminescence lifetimes of the n = 2 level in a large quantum well show a clear nonmonotonic dependence on the density of optically generated carriers. Varying the power density over five orders of magnitude we prove directly the high efficiency of carrier-carrier interaction for intersubband scattering when longitudinal-optical phonon emission is suppressed. For low densities, the observed n = 2 decay times get shorter (from 40 down to 5 ps) as the density is increased. At high densities Pauli blocking

The study of semiconductor interfaces and of solid interfaces in general requires novel instrument capable to investigate the lateral fluctuations of properties on a microscopic scale. We present the first result of a major effort in that framework, whose main objective is the exploitation of the unique characteristics of free electron laser (FEL) infrared sources. The background was provided by our previous development of FEL-based techniques to measure interface barriers with high accuracy and reliability

The dual wavelength Bi-vertical cavity surface-emitting laser

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Fabrication of ultra-small bimorph cantilevers for high-speed AFM of biological samples

Towards lasing systems for distributed fibre sensing

Extending the Supercontinuum Spectrum in Fully Etched Thick Aluminum Nitride Waveguides

Wide-field third-harmonic imaging of femtosecond laser-induced in-volume modifications

Reliability characteristics of microfabricated Rb mini-lamps for optical pumping in miniature atomic clocks and magnetometers

Characterization of the auditory system responses to infrared neural stimulation of the cochlear nucleus

Microfabrication and packaging of a Rubidium vapor cell as a plasma light source for MEMS atomic clocks

ArF laser induced refractive index and luminescence changes in Bi-doped aluminosilicate fibers - INVITED

2-μm wavelength range InGa(Al)As/InP-AlGaAs/GaAs wafer fused VCSELs for spectroscopic applications

Ammonia monitoring at trace level using photoacoustic spectroscopy in industrial and environmental applications

Near-field autocorrelation spectroscopy of disordered semiconductor quantum wells

Distributed measurement of chromatic dispersion by four-wave mixing and Brillouin optical-time-domain analysis

Attachment-induced ionization instability in electronegative capacitive RF discharges

Towards a room-temperature polariton amplifier

Level repulsion of exciton states in disordered semiconductor nanostructures

An optical modulator

Net coherent optical gain in strongly pumped semiconductor microcavities

Diode-pumped solid body laser used in ophthalmology comprises an acoustic-optical modulator, a laser crystal, a delay plate and a crystal that doubles the frequency of the laser beam

Density dependence of carrier-carrier-induced intersubband scattering in GaAs/AlxGa1-xAs quantum wells

Interface applications of scanning near-field optical microscopy with a free electron laser