Search results for "Far-infrared"
showing 10 items of 34 documents
Er3+-doped GeGaSbS glasses for mid-IR fibre laser application: Synthesis and rare earth spectroscopy
2008
International audience; With an infrared transparency extended to 10 µm, low multiphonon relaxation rates and suitable rare earth solubility, sulphide glasses in the Ge-Ga-Sb-S system allow radiative emission from rare earth ions in the mid-IR range. The Er3+ ion, widely studied in glass fibres for optical amplification at 1.5 µm, presents an interesting transition for mid-IR applications around 4.5 µm (4I9/2→ 4I11/2). Thus, the aim of this work is to evaluate the Er3+-doped Ge20Ga5Sb10S65 glass as a potential fibre laser source operating in the 3-5 µm mid-IR spectral region. For that purpose, absorption and emission spectra were recorded from visible to mid-IR and the radiative lifetimes o…
MICRO- AND NANO-STRUCTURES OF NOMINALLY PURE STOICHIOMETRIC LITHIUM NIOBATE SINGLE CRYSTAL IN RAMAN SPECTRA
2009
ABSTRACT The authors show that bandwidths in Raman spectra of ferroelectric photo-refractive single crystals may depend on wavelength of laser radiation exciting the spectrum. Raman bands of lithium niobate single crystals are broader if the spectrum is excited by laser radiation in visible as compared with the spectrum excited by infrared laser radiation. Local microscopic structural heterogeneities of altered index of refraction are shown to appear in parts of the crystal under laser irradiation. Under visible radiation the structural heterogeneities provide additional contribution to broadening of Raman bands. Similar microscopic heterogeneities are practically absent at laser irradiatio…
Infrared pulsed laser deposition of niobium nitride thin films
2011
We have successfully fabricated superconducting niobium nitride thin films on single crystals of magnesium oxide using a pulsed laser deposition technique where 1064 nm (photon energy ~1.16 eV) laser pulses from an Nd:YAG laser were used for ablation. A correlation between the superconducting transition temperature, the nitrogen base pressure during deposition and the lattice parameter of the produced NbN films was observed. Superconductor-insulator-normal metal junctions fabricated using these NbN films as the superconductor revealed nonlinear electrical characteristics at 4.2 K associated with quasiparticle tunneling.
Tunable Dual-Wavelength Thulium-Doped Fiber Laser Based on FBGs and a Hi-Bi FOLM
2017
A tunable dual-wavelength thulium doped fiber laser is demonstrated experimentally. For the first time for the 2- $\mu \text{m}$ wavelength band we propose the independent tuning of the generated laser lines based on fiber Bragg gratings and the use of a Hi-Bi fiber optic loop mirror for the fine adjustment of the cavity losses to obtain stable dual-wavelength operation. Dual-wavelength laser generation with the laser lines separation in the range from 0.3 to 6.5 nm is obtained. The laser emission exhibits an optical signal-to-noise ratio better than 56 dB. Improved stability with output power fluctuations less than 1 dB is observed in dual-wavelength generation with equal power of lines.
Changes in Amorphous Hydrogenated Carbon Films by Ultraviolet and Infrared Laser Irradiation
2013
Amorphous hydrogenated carbon lms were formed on the Si (100) wafers by a direct-ion beam deposition method from pure acetylene and acetylene hydrogen gas mixtures. The lms were irradiated with a nanosecond Nd:YAG laser working at the rst harmonics (λ1 = 1064 nm), the fourth harmonics (λ4 = 266 nm) or with a Nd:YVO4 laser working at the third harmonic (λ3 = 355 nm). The lms were studied by the Raman scattering, micro-Fourier transform infrared and Fourier transform infrared spectroscopies, null-ellipsometry, optical and scanning electron microscope, and Vickers hardness method. Irradiation by the wavelength λ1 = 1064 nm leads to graphitization and formation of the silicon carbide, because o…
50 mJ/30 ns FTIR Q-switched diode-pumped Er:Yb:glass 1.54 μm laser
2001
Abstract 50 mJ Q-switched output at 30 ns pulse duration was demonstrated with a transversely diode-pumped bulk Er 3+ :Yb 3+ :glass 1.54 μm laser system of uncomplicated and compact design, using a piezoelectrically driven FTIR shutter. In long-pulse operation, 360 mJ output was obtained for 2.65 J incident optical pump energy. Maximum optical slope efficiencies of 20.5% and 5.4% were measured in long-pulse and Q-switched operation, respectively. Optimum Q-switch timing was studied taking into account the Yb 3+ →Er 3+ energy transfer process and was correlated with free-running delay parameters.
Raman Studies of Photorefractive Lithium Niobate Single Crystals
2014
A study of Raman spectra of lithium niobate single crystals: stoichiometric, ostensibly pure congruent LiNbO3, and congruent LiNbO3 containing admixture of yttrium is reported. Raman bands observed in spectra excited by visible laser radiation are thoroughly compared to the same bands excited by infrared laser radiation. The broadening of Raman bands excited by radiation of shorter wavelengths is attributed to photo-refraction induced by visible radiation (514 nm) while being absent under infrared radiation (1064 nm). Attributing the effect of photo-refraction to radiation-induced structural changes in the illuminated part of the crystal lattice the authors interpret the observed broadening…
Efficient pulsed 946-nm laser emission from Nd:YAG pumped by a titanium-doped sapphire laser
2008
Efficient pulsed room-temperature laser emission at 946 nm is obtained from a Nd:YAG rod pumped by a Ti-doped sapphire laser in the free-running mode. Three bonded YAG rods of 3-mm diameter with different Nd concentrations and active lengths were tested. A maximum output energy of 83.5 mJ at 3 Hz was obtained with a slope efficiency of 32.3% in an end-pumping configuration.
Continuous-wave dual-wavelength operation at 1062 and 1338nm in Nd3+:YAl3(BO3)4 and observation of yellow laser light generation at 592nm by their se…
2009
Abstract We report simultaneous oscillation in continuous wave at 1062 and 1337 nm in a Nd 3+ :YAl 3 (BO 3 ) 4 nonlinear crystal associated to the infrared laser channels 4 F 3/2 → 4 I 11/2 and 4 F 3/2 → 4 I 13/2 of Nd 3+ . Generation of yellow laser light at 592 nm produced by Type I self-sum-frequency-mixing of both fundamental infrared laser waves is observed under non-optimal phase matching conditions.
Large area strip edgeless detectors fabricated by plasma etching process
2007
This work presents the last results from large area edgeless detector, fabricated by Plasma Etching Process to reduce the conventional width of the terminating structure of position sensitive detectors to the detector rim.. A current terminating ring is used to decouple the electrical behavior of the surface from the sensitive volume within a few tens of micrometers. The detectors have been illuminated using an infrared laser and their surface scanned in order to understand their collection behavior at the cut edge. The detectors have very high efficiency up to the insensitive area which is located about 60 mum from the detector edge.