ABSTRACT
Rare earth ion doped materials are means to obtain cost-effective infrared light sources, with enough brilliance for applications such as gas sensing. Within a sulfide matrix, the simultaneous luminescence of both Pr3+ and Dy3+ in the Ga5Ge20Sb10S65 glass is reported. The use of these two rare earths is giving rise to a broad continuous luminescence in the 2.2-5.5 µm wavelength range, which could be used as a mid-infrared light source for gas-sensing applications. The demonstration of CO2 and CH4 detection using a fiber drawn from these materials is reported.
ABSTRACT
Ce-Doped SiOxNy films are deposited by magnetron reactive sputtering from a CeO2 target under a nitrogen reactive gas atmosphere. Visible photoluminescence measurements regarding the nitrogen gas flow reveal a large emission band centered at 450 nm for a sample deposited under a 2 sccm flow. Special attention is paid to the origin of such an emission at high nitrogen concentration. Different emitting centers are suggested in Ce doped SiOxNy films (e.g. band tails, CeO2, Ce clusters, Ce3+ ions), with different activation scenarios to explain the luminescence. X-ray photoelectron spectroscopy (XPS) reveals the exclusive presence of Ce3+ ions whatever the nitrogen or Ce concentrations, while transmission electron microscopy (TEM) shows no clusters or silicates upon high temperature annealing. With the help of photoluminescence excitation spectroscopy (PLE), a wide excitation range from 250 nm up to 400 nm is revealed and various excitations of Ce3+ ions are proposed involving direct or indirect mechanisms. Nitrogen concentration plays an important role in Ce3+ emission by modifying Ce surroundings, reducing the Si phase volume in SiOxNy and causing a nephelauxetic effect. Taking into account the optimized nitrogen growth parameters, the Ce concentration is analyzed as a new parameter. Under UV excitation, a strong emission is visible to the naked eye with high Ce3+ concentration (6 at%). No saturation of the photoluminescence intensity is observed, confirming again the lack of Ce cluster or silicate phase formation due to the nitrogen presence.
ABSTRACT
We report for the first time the conversion of incoherent infrared light around 4.4µm into a near-infrared signal at 810nm in erbium-doped GaGeSbS fibers and bulk glass samples. This energy conversion is made possible by pumping erbium doped chalcogenide samples at 982 nm and simultaneously exciting them with a 4.4µm infrared signal. This result paves the way for the development of an "all-optical" gas sensor able to detect various gas traces using a remote detection based on commercial silica fibers.
ABSTRACT
Efficient and compact laser-diode end-pumped Nd:GGG simultaneous multiwavelength continuous-wave lasers at â¼1059, â¼1060 and â¼1062 nm were first demonstrated in a free-running 30 mm plano-concave laser cavity. The maximum output power was up to 3.92 W with a slope efficiency of about 53.6% with respect to the absorbed pump power. By inserting a 0.1 mm optical glass plate acting as a Fabry-Pérot etalon, a single-wavelength laser at â¼1067 nm with a maximum output power of 1.95 W and a slope efficiency of 28.5% can be obtained. Multiwavelength lasers, including those at â¼1054 or â¼1067 nm, were also achievable by suitably tilting the glass etalon. These simultaneous multiwavelength lasers provide a potential source for terahertz wave generation.
ABSTRACT
The polarized emission spectra for the 3P0â1G4 emission transition of the Pr3+ ion around 910 nm in the Pr3+:LiYF4 (Pr:YLF) laser crystal were registered and calibrated in unit of cross sections for the first time. Continuous-wave (CW) laser operation is demonstrated at 915 nm in π polarization by pumping the crystal with an optically pumped semiconductor laser (OPSL) at 479.2 nm. An output power of 218 mW is thus obtained with a laser slope efficiency of about 24% for an output coupler (OC) transmission of 1.9%. CW laser operation is also demonstrated at 907 nm in σ polarization by using a thin plate oriented at Brewster angle. An output power of about 89 mW with a slope efficiency of about 10% is then obtained for an OC transmission of 0.8%.The round-trip cavity losses are estimated for different experimental cavity configurations to be about 1% and the typical beam quality M2 factors measured in the transverse x and y directions are found equal to about 1.07 and 1.04, respectively. Finally, we also report on a double laser wavelength operation by using an OC with a transmission of about 0.05%, such effect resulting from joint-etalon effects inside the cavity.
Subject(s)
Lasers, Solid-State , Energy Transfer , Equipment Design , Equipment Failure AnalysisABSTRACT
By using a high-brightness fiber pump laser, we demonstrate a pure Kerr-lens mode-locked (ML) Yb:CaF(2) oscillator. The laser delivers 68 fs pulses with 2.3 W average power at 73 MHz repetition rate and an optical-to-optical efficiency of 33% is achieved. To the best of our knowledge, this is the first demonstration of Kerr-lens mode-locking in Yb:CaF(2). Incidentally, we report here the highest average power ever achieved for a sub-100-fs active Kerr-lens ML Yb-bulk oscillator.
ABSTRACT
We report the basic luminescence properties and the continuous-wave (CW) laser operation of a Pr(3+)-doped KYF(4) single crystal in the Red and Orange spectral regions by using a new pumping scheme. The pump source is an especially developed, compact, slightly tunable and intra-cavity frequency-doubled diode-pumped Nd:YAG laser delivering a CW output power up to about 1.4 W around 469.1 nm. At this pump wavelength, red and orange laser emissions are obtained at about 642.3 and 605.5 nm, with maximum output powers of 11.3 and 1 mW and associated slope efficiencies of 9.3% and 3.4%, with respect to absorbed pump powers, respectively. For comparison, the Pr:KYF(4) crystal is also pumped by a InGaN blue laser diode operating around 444 nm. In this case, the same red and orange lasers are obtained, but with maximum output powers of 7.8 and 2 mW and the associated slope efficiencies of 7 and 5.8%, respectively. Wavelength tuning for the two lasers is demonstrated by slightly tilting the crystal. Orange laser operation and laser wavelength tuning are reported for the first time.
ABSTRACT
We report on the first observation of optical signal amplification in the visible range into praseodymium doped ZBLA glass channel waveguides obtained by ion exchange. Up to 30% signal amplification was obtained at 639 nm. This result shows the potential of rare earth doped fluoride glasses in the form of channel waveguides for integrated solid state visible laser sources.
ABSTRACT
High-power diode-pumped laser operation at 992-993 nm under a pumping wavelength of 981 of 986 nm is demonstrated with Yb:CaF2 operating at cryogenic temperature (77 K), leading to extremely low quantum defects of 1.2% and 0.7%, respectively. An average output power of 33 W has been produced with an optical efficiency of 35%. This represents, to the best of our knowledge, the best laser performance ever obtained at such low quantum defects on intense laser lines.
ABSTRACT
We present a high-power diode-pumped Yb:CaF(2) laser operating at cryogenic temperature (77 K). A laser output power of 97 W at 1034 nm was extracted for a pump power of 245 W. The corresponding global extraction efficiency (versus absorbed pump power) is 65%. The laser small signal gain was found to be equal to 3.1. The laser wavelength could be tuned between 990 and 1052 nm with peaks that correspond well to the structure of the gain cross-section spectra registered at low temperature.
ABSTRACT
To realize an electrically pumped compact mid-IR microlaser, the optical properties of a Cr(2+):ZnSe film deposited by rf magnetron cosputtering were compared with those of a single crystal. The mid-IR room temperature photoluminescence efficiency of the film appears only twice less than the one of the single crystal under direct (1850 nm) and indirect (458 nm) excitations. The smaller Cr(2+) fluorescence lifetime values of the film were attributed to the presence in the film of a large amount of chromium in a valence state different from Cr(2+) and of structural defects in the ZnSe host matrix.
Subject(s)
Chromium/chemistry , Crystallization/methods , Membranes, Artificial , Selenium Compounds/chemistry , Zinc Compounds/chemistry , Light , Materials Testing , Refractometry , Scattering, RadiationABSTRACT
The refractive index changes which can be induced in the Nd:YVO(4), Nd:GdVO(4) and Nd:KGW high gain laser crystals, when their Nd(3+) laser active ions are pumped from their ground- to excited- energy levels, have been carefully measured and characterized. By using two complementary optical techniques based on pump-probe interferometry and transient diffraction grating, the electronic and thermal contributions to the observed refractive index variations have been accurately determined and successfully exploited to derive various parameters such as polarizability changes, thermo-optic coefficients and thermal diffusivities.
Subject(s)
Gases/chemistry , Lasers, Semiconductor , Refractometry/instrumentation , Refractometry/methods , Equipment Design , Equipment Failure AnalysisABSTRACT
Femtosecond mode-locked operation is demonstrated for the first time, to our knowledge, with a Yb:SrF(2) crystal. The shortest pulse duration is 143 fs for an average power of 450 mW. The highest average power is 620 mW for a pulse duration of 173 fs. Since Yb:SrF(2) corresponds to the longest-lifetime Yb-doped crystal with which the mode-locking operation has been achieved, a detailed analysis is carried out to characterize the quality of the solitonlike regime.
ABSTRACT
We demonstrate the generation of 99 fs pulses by a mode-locked laser oscillator built around a Yb:CaF(2) crystal. An average power of 380 mW for a 13 nm bandwidth spectrum centered at 1053 nm is obtained. The short-pulse operation is achieved thanks to a saturable absorber mirror and is stabilized by the Kerr lens effect. We investigated the limits of the stabilization process and observed a regime slowly oscillating between mode locking and Q switching.
ABSTRACT
We report an in situ thermal study of Yb-doped fluorite crystals Yb:CaF(2) and Yb:SrF(2) under high power pumping, with or without laser operation. The experiment combines simultaneously thermography and measurement of the thermal aberrations. This setup allows us to measure temperature gradients, thermal lens, and absorption coefficients. From these measurements, we evaluate the thermal conductivity, fractional thermal load, and thermo-optic coefficient. Great differences are observed between the lasing and non lasing regimes. Our measured thermal lenses are greater than what are expected from the thermo-optic parameters found in previous work. Based on this thermal study, we design a laser cavity operating with large output power and TEM(00), leading to better performances for Yb:CaF(2) than Yb:SrF(2).
ABSTRACT
We report the first observation to our knowledge of room-temperature continuous-wave laser operation of a Pr(3+):KY(3)F(10) single crystal at 644.5 nm, pumped by a blue GaN laser diode emitting at 446 nm. With a 2.5% transmission output coupler and a nonoptimized optical cavity, an output power of 39 mW was obtained at 644.5 nm with a laser threshold of 125 mW and a differential slope efficiency of 23%.
ABSTRACT
We report what is believed to be the first demonstration of a high-power passively mode-locked diode-pumped femtosecond laser based on an Yb3+:CaF2 single crystal, directly pumped by a 15-W fiber-coupled laser diode. With a 5-at. % Yb3+ -doped sample and prisms for dispersion compensation we obtained pulses as short as 150 fs, with 880 mW of average power and up to 1.4-W average output power, with a pulse duration of 220 fs, centered at 1049 nm. The laser wavelength could be tuned from 1040 to 1053 nm in the femtosecond regime. Using chirped mirrors for dispersion compensation, the oscillator provided up to 1.74 W of average power, with a pulse duration of 230 fs, corresponding to a pulse energy of 20 nJ and a peak power of 85 kW.
ABSTRACT
Results of diode-pumped cw laser operation of an Yb3+:CaF2 single crystal are reported for what is to our knowledge the first time. With a 5-at.% Yb3+ -doped sample we obtained 5.8-W output power at 1053 nm for 15 W of incident power at 980 nm. The laser wavelength could be tuned from 1018 to 1072 nm, and a small-signal gain as high as 1.8 was achieved, showing the great potential of Yb3+:CaF2 as an amplifier medium for femtosecond pulses.
