Showing papers on "Slope efficiency published in 1997"
TL;DR: Er3+-doped tellurite singlemode fiber is fabricated and signal amplification and laser oscillation are demonstrated for the first time in this article, where a small signal gain of 16 dB at 1560 nm is obtained for a pump power of 130 mW at 978 nm.
Abstract: Er3+-doped tellurite singlemode fibre is fabricated and signal amplification and laser oscillation are demonstrated for the first time. A small-signal gain of 16 dB at 1560 nm is obtained for a pump power of 130 mW at 978 nm. A laser oscillation is observed with a threshold pump power of 120 mW at 978 nm and a slope efficiency of 0.65% using this fibre.
294 citations
TL;DR: Spectroscopic properties and laser performance of Y b-doped tungstates at pulsed Ti:sapphire laser pumping are reported.
Abstract: Spectroscopic properties and laser performance of Yb-doped tungstates at pulsed Ti:sapphire laser pumping are reported. Room-temperature lasing near 1025 nm is demonstrated in Yb:KY(WO4)2 and Yb:KGd(WO4)2, with a slope efficiency as great as 86.9%.
283 citations
TL;DR: In this paper, a slope efficiency of Yb-lasers up to 78% has been obtained under pumping by both Ti-sapphire laser and InGaAs laser diodes.
Abstract: Room temperature cw laser action of Yb3+-doped KY(WO4)2 and KGd(WO4)2 crystals at 1.025 μm and Er, Yb : KY(WO4)2 at 1.54 μm has been demonstrated under pumping by both Ti-sapphire laser and InGaAs laser diodes. A slope efficiency of Yb-lasers up to 78% has been obtained.
222 citations
TL;DR: Modeling studies of quasi-three-level laser oscillators are presented, the validity of which was revealed by Ti:Al(2)O(3)-pumped Yb:YAG laser experiments, and these results are shown to be in excellent agreement with the theory.
Abstract: We present modeling studies of quasi-three-level laser oscillators, the validity of which was revealed by Ti:Al2O3-pumped Yb:YAG laser experiments, and these results are shown to be in excellent agreement with the theory. As much as 75% slope efficiency was obtained with a hemispherical laser cavity. Previous modeling calculations of laser performance have been valid only for certain special cases, restricting application to TEM00 Gaussian beam pumping and lasing profiles. This analysis may be applied to other longitudinally pumped quasi-three-level laser media in which the modes are not only TEM00 Gaussian beams but also other higher-order transverse modes, including the top-hat pumping profile that can be used to model transverse pumping schemes.
187 citations
TL;DR: In this paper, a self-frequency doubling method using GdCOB has been demonstrated with a cw Ti:sapphire pump source, where the crystal was shown to lase along its three crystallophysic axes.
175 citations
TL;DR: Significant improvements have been obtained for solid-state dye lasers with doped xerogels by using longitudinal pumping with a frequency-doubled Q-switched Nd: YAG laser, and newly prepared deoxygenated samples exhibited even greater lifetimes.
Abstract: Significant improvements have been obtained for solid-state dye lasers with doped xerogels. By using longitudinal pumping with a frequency-doubled Q-switched Nd: YAG laser, we obtained as much as 86% slope efficiency and 5 x 10(5) pulses lifetime. Furthermore, newly prepared deoxygenated samples exhibited even greater lifetimes.
125 citations
TL;DR: A CdSe optical parametric oscillator pumped by a 2.79-mum, Cr, Er:YSGG laser yielded a 59% signal-plus-idler slope efficiency (eta), a total idler output of 1.2-2.4mJ between 8.5 and 12.3 mum, and an idler beam that was 2.5 times the diffraction limit.
Abstract: A CdSe optical parametric oscillator (OPO) pumped by a 2.79-mum , Cr, Er:YSGG laser yielded a 59% signal-plus-idler slope efficiency (eta), a total idler output of 1.2-2.4mJ between 8.5 and 12.3 mum , and an idler beam that was 2.2-2.5 times the diffraction limit. A ZnGeP(2) OPO operated with a lower threshold, eta = 29% , and a forward idler output of 0.7-2.4 mJ from 6.9 to 9.9 microm . The signal and idler bandwidths were typically 4 cm(-1) for each OPO.
108 citations
TL;DR: In this paper, a simple design rule for diode-laser pumped quasi-three-level laser by using the M/sup 2/factor was presented, and the validity of this model was demonstrated by diodepumped Yb:YAG laser experiments.
Abstract: We present a simple design rule for diode-laser pumped quasi-three-level lasers by using the M/sup 2/ factor. The validity of this model was demonstrated by diode-pumped Yb:YAG laser experiments. The maximum output power of 1.33 W and optical slope efficiency of 63% were obtained in a 400-/spl mu/m Yb:YAG chip miniature laser. Using a 200-/spl mu/m Yb:YAG chip, a 70% optical slope efficiency was reached. In a coupled-cavity configuration, with a quartz birefringent tuning filter, 8.2 THz (29 nm) of tuning was obtained at room temperature. By changing to a calcite birefringent filter, single-axial-mode oscillation with an output power of 500 mW was observed.
103 citations
TL;DR: A high-repetition-rate femtosecond optical parametric oscillator (OPO) that was broadly tunable in the mid infrared and based on quasi-phase matching in periodically poled lithium niobate is described.
Abstract: We describe a high-repetition-rate femtosecond optical parametric oscillator (OPO) that was broadly tunable in the mid infrared. The all-solid-state-pumped OPO was based on quasi-phase matching in periodically poled lithium niobate. The idler was tunable from approximately 1.7 µm to beyond 5.4 µm, with maximum average power levels greater than 200 mW and more than 20 mW of average power at 5.4 µm. We used interferometric autocorrelation to characterize the mid-infrared idler pulses, which typically had durations of 125 fs. This OPO had a pumping threshold as low as 65 mW of average pump power, a maximum conversion efficiency of >35% into the near-infrared signal, a slope efficiency for the signal of approximately 60%, and a maximum pump depletion of more than 85%.
93 citations
TL;DR: Room-temperature laser action from Cr(2+)-doped Cd(0.85)Mn( 0.15)Te has been demonstrated for what is believed to be the first time, and pulsed laser operation centered at ~2.5mu m is achieved.
Abstract: Room-temperature laser action from Cr2+-doped Cd085Mn015Te has been demonstrated for what is believed to be the first time We achieved pulsed laser operation centered at ∼25 µm by pumping into the mid-infrared absorption band of Cr 2+ ions by use of the 1907-µm output of a H2 Raman-shifted Nd:YAG laser The output of the free-running Cr2+:Cd085 Mn015Te laser had a width of ∼50 nm (FWHM), and the slope efficiency was calculated to be 55% under nonoptimum conditions
91 citations
TL;DR: The lasing performance of a waveguiding layer of Ti:sapphire, of ~12-mum thickness, grown by pulsed laser deposition from a 0.12-wt.% Ti(2)O(3) Ti:Sapphire single-crystal target onto an undoped z-cut sapphire substrate is documented.
Abstract: This paper documents the lasing performance of a waveguiding layer of Ti:sapphire, of ~12µm thickness, grown by pulsed laser deposition from a 0.12 wt % Ti2O3 Ti:sapphire single crystal target onto an undoped z-cut sapphire substrate. Lasing around 800nm is observed, when the waveguide layer is pumped by an argon ion laser, running on all blue green lines, with an absorbed power threshold of 0.56W using high reflectivity (R>98%) mirrors. Using a 5% pump duty cycle and a T = 35% output coupler, a slope efficiency of 26% with respect to absorbed power is obtained, giving quasi-CW output powers in excess of 350mW.
TL;DR: In this paper, a method of providing asymmetric feedback in the triangular ring laser structure was devised through simple alterations of the waveguide shape, and two kinds of alterations were designed and implemented, one being the "optical diode" and the other being the tapered waveguide.
Abstract: A method of providing asymmetric feedback in the triangular ring laser structure was devised through the simple alterations of the waveguide shape. Two kinds of alterations were designed and implemented, one being the “optical diode,” the other being the tapered waveguide. Unidirectional operation was achieved for the ring lasers, with a single-beam slope efficiency of 0.23 W/A, which was the highest single-beam slope efficiency reported for semiconductor ring lasers.
TL;DR: By pumping with a cw diode-pumped Nd:YAG laser operating at 946nm laser operation of a new Yb-doped phosphate glass with 440mW cw output power and a slope efficiency of 48% with respect to the absorbed pump power was achieved at room temperature.
TL;DR: In this article, a 2µm laser operation of a diode-pumped Tm-doped YAG planar waveguide was reported, and the fabrication and characterisation of such layers grown by liquid phase epitaxy were described.
TL;DR: In this article, a Ti:sapphire-pumped Er 3+ :YLF laser is built and compared with a commercially available Er 3 + :LYF laser.
TL;DR: A scheme whereby the self-pulsation that commonly occurs in an erbium-doped fiber laser can be suppressed by the addition of a low-power laser as an auxiliary pump is proposed.
Abstract: We propose a scheme whereby the self-pulsation that commonly occurs in an erbium-doped fiber laser can be suppressed. The scheme consists of the addition of a low-power laser as an auxiliary pump. The required auxiliary pump power is only a few percent of the output lasing power. There is reasonable agreement between experimental and theoretical results.
TL;DR: A demonstration of low propagation loss combined with the fact that these waveguides have a very high numerical aperture (0.75) makes pulsed-laser-deposited thin films attractive for high-power diode-pumped devices.
Abstract: We report the laser performance of a low propagation loss neodymium doped Gd3Ga5O12 (Nd:GGG) waveguide fabricated by pulsed laser deposition. An 8µm thick crystalline Nd:GGG film grown on an undoped Y3Al5O12 (YAG) substrate lases at 1.060µm and 1.062µm, when pumped by a Ti:sapphire laser operating at 740nm or 808nm. Using a 2.2% output coupler a 1060nm laser threshold of 4mW and a slope efficiency of 20% were observed. Laser action has also been achieved, we believe for the first time in Nd:GGG, on the quasi-three level 937nm transition. With a 2% output coupler at this wavelength a laser threshold of 17mW and a 20% slope efficiency were obtained. This demonstration of low propagation loss combined with the fact that these waveguides have a very high numerical aperture, make pulsed laser deposited thin films attractive for high power diode pumped devices.
TL;DR: An efficient, simple, and scalable diode side-pumping configuration of a solid-state rod laser using a diffusive cavity and diode powers are transferred by a thin plate into the cavity is proposed.
Abstract: We propose an efficient, simple, and scalable diode side-pumping configuration of a solid-state rod laser. The rod is excited in a diffusive cavity and diode powers are transferred by a thin plate into the cavity. In multitransverse-mode cw operation, 40 W of laser power was generated with an optical-to-optical slope efficiency of 52.2% at a diode output power of 135.1 W and an electrical input power of 327.3 W into the diodes. These values correspond to an optical-to-optical total efficiency of 29.6% and an electrical-to-optical total efficiency of 12.2%. The electrical-to-optical slope efficiency was 30.3%.
TL;DR: Periodically poled lithium niobate has been used in a singly resonant optical parametric oscillator pumped by a cw mode-locked Ti:sapphire laser.
Abstract: Periodically poled lithium niobate has been used in a singly resonant optical parametric oscillator pumped cw mode-locked Ti:sapphire laser. A tuning range of 1.15 to 2.4µm was achieved when the pump was tuned, and this range was limited only by the mirror reflection bandwidth. Thresholds as low as 18 mW and an overall slope efficiency of 44% were observed, with average output powers of 130 mW (70 mW) for the signal (idler).
TL;DR: In this article, the authors reported room-temperature (RT) continuous-wave (CW) photopumped operation of long-wavelength vertical-cavity surface-emitting lasers (VCSELs) employing a Ga/sub 0.7/In/Sub 0.993/-GaAs multiple-quantum-well (MQW) active layer grown directly on a GaAs-AlAs distributed Bragg reflector (DBR).
Abstract: We report room-temperature (RT) continuous-wave (CW) photopumped operation of long-wavelength vertical-cavity surface-emitting lasers (VCSELs) employing a Ga/sub 0.7/In/sub 0.3/N/sub 0.007/As/sub 0.993/-GaAs multiple-quantum-well (MQW) active layer grown directly on a GaAs-AlAs distributed Bragg reflector (DBR). Evidence for laser oscillation includes spectral linewidth narrowing, clamping of spontaneous emission, and a distinct increase in slope efficiency at threshold. By taking advantage of lateral growth rate nonuniformity, we obtained laser emission over an extremely broad 110-nm wavelength range, from 1.146-1.256 /spl mu/m. Equivalent threshold current density over this range was estimated at 3.3-10 kA/cm/sup 2/.
TL;DR: In this paper, the authors used tunneling for injection of electrons into a quantum well active region to increase the electronic confinement and improve the lasing performance for small active areas, achieving a lasing threshold of 36 μA with a slope efficiency of 23% and a 52% slope efficiency for a 4 μm device with a 92 μA threshold.
Abstract: Data are presented on vertical-cavity surface-emitting lasers that use tunneling for injection of electrons into a quantum well active region. The tunneling injection scheme increases the electronic confinement and improves the lasing performance for small active areas. A lasing threshold of 36 μA with a slope efficiency of 23% is achieved for a 2.5 μm device, and a 52% slope efficiency is achieved for a 4 μm device with a 92 μA threshold.
TL;DR: An upconversion cascade laser in an erbium-doped ZBLAN fiber emitting simultaneously on the three transitions is reported on, representing more than 90% of the theoretical slope efficiency.
Abstract: We report on an upconversion cascade laser in an erbium-doped ZBLAN fiber emitting simultaneously on the three transitions 4S3/2 -> 4I9/2 at 1.7 um, 4I11/2 -> 4I13/2 at 2.7 um, and 4I13/2 -> 4I15/2 at 1.6 um. At moderate pump powers, the laser transition at 1.6 um supports 2.7-um lasing and permits a slope efficiency at 2.7 um of 15% versus launched pump power. Above the threshold of upconversion lasing at 1.7 um, the slope efficiency at 2.7 um increases to 25.4%. Taking pump excited-state absorption into account, this value represents more than 90% of the theoretical slope efficiency. A transversely single-mode output power of 99 mW is achieved at 2.7 um.
TL;DR: In this article, an intracavity frequency-doubled 10% LaSc3(BO3)4 (Nd : LSB) laser was investigated in different resonator configurations and in different operation modes under continuous wave (cw) and quasi-cw laser-diode pumping with a Cr4+ : YAG passive modulator and a KTP crystal.
Abstract: An intracavity frequency-doubled 10%Nd : LaSc3(BO3)4 (Nd : LSB) laser was investigated in different resonator configurations and in different operation modes under continuous wave (cw) and quasi-cw laser-diode pumping With a Cr4+ : YAG passive modulator and a KTP crystal the second-harmonic output power at 531 nm amounted to 190 mW in Q-switched TEM00 mode at 750 mW of pump power In a sandwich resonator, when all the optical elements were in direct contact with each other, 08 W of green output power was obtained in cw mode under 27 W of pump power with a slope efficiency of 44% In the same setup under fiber-coupled diode-laser array pumping (56 W of incident power), 12 W of green output power was achieved in cw mode and 14 W in quasi-cw mode
TL;DR: In this paper, the effect of various types of spatial nonuniformities on the performance of semiconductor diode lasers was examined, and it was shown that the non-uniformity of the nonradiative lifetime has little effect on the slope efficiency at high injection levels, but produces a signature softening of the threshold abruptness.
Abstract: We examine the effect of various types of spatial nonuniformities on the performance of semiconductor diode lasers. Light versus current (L-I) characteristics are modeled by solving the coupled rate equations for the carrier density, photon density, carrier temperature, and lattice temperature. In cases of macroscopic nonuniformities, that is, when the fluctuation correlation length (/spl Lambda//sub F/) is longer than the carrier diffusion length (L/sub D/), the cavity is divided into a large number of segments, and separate rate equations are solved for each segment. Type-II antimonide quantum wells are used as the model diode laser system. Macroscopic nonuniformities of the nonradiative lifetime are shown to have little effect on the slope efficiency at high injection levels, but produce a signature softening of the threshold abruptness if the nonuniformity is large enough. This results from the nonuniformity of the carrier concentration and consequent mixture of gain and loss regions. For the case of microscopic bandgap fluctuations (L/sub D//spl Gt//spl Lambda//sub F/), inhomogeneous broadening of the gain spectrum leads to an increase of the threshold current density, which is accompanied by only a small reduction of the efficiency. However, in the complementary limit of macroscopic bandgap fluctuations (L/sub D/
TL;DR: In this paper, a CaGdAlO4 laser crystal was investigated, which was grown by the Czochralski method and the atomic concentration of Nd3+ in the melt was 2%.
Abstract: A new Nd3+-doped CaGdAlO4 laser crystal was investigated. This crystal was grown by the Czochralski method. The atomic concentration of Nd3+ in the melt was 2%. The absorption and luminescence spectra were analysed and the Stark structure of the upper and lower active levels was determined. The lifetime of the upper level was ~140 μs. The stimulated emission cross section at the 1078 nm wavelength was 1.1 × 10-19cm2 for the E∥c polarisation. A GaAlAs diode, with an output power of 3 W emitting at the wavelength 806.5 nm, was used as the pump source. The slope efficiency was 37% at the 1078 nm wavelength when the output mirror transmission was 5%. The output radiation power of the crystal laser was 360 mW when the absorbed pump power was 1.29 W.
TL;DR: In this article, an Er3+:LiYF4 laser was demonstrated with pulsed Ti:sapphire pumping at 973 nm, where the upconversion rate is negative at threshold but increases strongly with rising pump pulse energy, thus enhancing the slope efficiency.
Abstract: A slope efficiency of 40% from an Er3+:LiYF4 laser is demonstrated under pulsed Ti:sapphire pumping at 973 nm. With reduction of the pump-pulse duration a significant decrease of the slope efficiency and an increase of the threshold is observed in the experiment and confirmed with high accuracy in a computer simulation. This behavior is due to interionic upconversion from the lower laser level, which leads to energy recycling into the upper laser level. The upconversion rate is negative at threshold but increases strongly with rising pump pulse energy, thus enhancing the slope efficiency. The conditions are derived that are necessary for achieving the high slope efficiency of the energy-recycling regime.
TL;DR: A 1.55 μm multiple quantum well laser heteroepitaxially grown on Si substrate operates under the severe aging condition of the light output of 5 mW/facet at 50 °C as mentioned in this paper.
Abstract: A 1.55 μm multiple quantum well laser heteroepitaxially grown on Si substrate operates under the severe aging condition of the light output of 5 mW/facet at 50 °C. The laser has been operating for more than 7000 h. The threshold current and the slope efficiency of the laser on Si at 20 °C are 32 mA and 0.19 W/A, respectively. The maximum operation temperature is above 80 °C.
TL;DR: In this article, an efficient high power cw Nd:YAG slab laser, partially end-pumped by diode laser stacks, and a novel beam shaping technique are reported.
TL;DR: In this article, a pulsed laser irradiation technique, using multiphoton absorption, was used to promote quantum-well intermixing in double-quantum-well GaAs-AlGaAs laser structures.
Abstract: We report the use of a pulsed laser irradiation technique, using multiphoton absorption, to promote quantum-well intermixing (QWI) in double-quantum-well GaAs-AlGaAs laser structures. The process requires neither ion implantation nor the deposition of dielectric caps. Differential bandgap shifts of up to 40 meV have been obtained between the control and the laser irradiated samples. Bandgap tuned lasers were fabricated from the intermixed samples and exhibited negligible changes in slope efficiency and only small increases (15%) in threshold current compared to as-grown devices.
TL;DR: In this article, a versatile high-power Nd:YAG laser system that combines the ease of end pumping with the stability and scaleability of symmetric multirod resonators was presented.