Showing papers on "Slope efficiency published in 1999"
TL;DR: In this article, the theoretically determined slope efficiency and threshold pump power for continuous wave (CW) operation of a Tm-doped silica fiber laser are presented, in conjunction with the published and measured spectroscopic parameters as input, the model was used to examine the fiber laser output for a variety of fiber and pump configurations.
Abstract: The theoretically determined slope efficiency and threshold pump power for continuous wave (CW) operation of a Tm-doped silica fiber laser are presented. The associated rate equations are solved using standard techniques and, in conjunction with the published and our measured spectroscopic parameters as input, the model was used to examine the fiber laser output for a variety of fiber and pump configurations. After good agreement was achieved between the model calculations and the published experimental measurements, the model was used to examine the relative performance of the fiber laser when the pump wavelength was varied over the /sup 3/F/sub 4/, /sup 3/H/sub 5/, and /sup 3/H/sub 4/ absorption bands of Tm/sup 3+/. The calculated maximum slope efficiencies were determined to be /spl sim/40, /spl sim/57, and /spl sim/84%, respectively, for each of the /sup 3/F/sub 4/, /sup 3/H/sub 5/, and /sup 3/H/sub 4/ absorption band pump schemes and the threshold pump power over the range of pump schemes was determined to vary by only 28%. The model was further used to analyze the fiber laser output when the fiber length, Tm/sup 3+/ concentration and /sup 3/H/sub 4/ energy level lifetime were varied and the consequences on the operation of the fiber laser with these variations are discussed.
302 citations
TL;DR: Room-temperature operation of an all-solid-state broadly tunable continuous-wave Cr(2+):ZnSe laser is reported, and continuous tunability from 2138 to 2760 nm is demonstrated.
Abstract: We report room-temperature operation of an all-solid-state broadly tunable continuous-wave Cr(2+):ZnSe laser. Output power of 250 mW, an absorbed power slope efficiency of 63%, and continuous tunability from 2138 to 2760 nm are demonstrated.
184 citations
TL;DR: In this paper, rare earth doped scandia and yttria have been grown from rhenium crucibles by the Czochralski technique, to the best of our knowledge.
Abstract: Rare earth doped scandia and yttria have been grown from rhenium crucibles by the Czochralski technique - to our knowledge for the first time. Spectroscopic data of Yb:Sc 2 O 3 are presented in detail and first laser experiments are reported. Despite the rather high crystal losses of about 2 % a slope efficiency of 37 % was obtained under diode pumping.
148 citations
TL;DR: An efficient pumping scheme that involves direct excitation of the upper lasing level of the Nd(3+) ion is demonstrated experimentally and the increase in optical efficiency indicates that laser material thermal loading can be substantially reduced.
Abstract: An efficient pumping scheme that involves direct excitation of the upper lasing level of the Nd3+ ion is demonstrated experimentally. The results obtained for direct upper laser level pumping of Nd:YAG R2 (869 nm) and Nd:YVO4 (880 nm) were compared with traditional ∼808-nm pump band excitation. A tunable cw Ti:sapphire laser was used as the pump source. In Nd:YAG, the oscillator slope efficiency increased by 10% and the threshold decreased by 11%. In Nd:YVO4, the slope efficiency increased by 5% and the threshold decreased by 11%. These results agree with theory. The increase in optical efficiency indicates that laser material thermal loading can be substantially reduced.
127 citations
TL;DR: 1.15 W of Gaussianlike (M(2) = 2) cw output at 2.94 mum from a diode laser end-pumped monolithic laser crystal composed of Er-doped yttrium aluminum garnet bonded to undoped YAG is demonstrated.
Abstract: We have demonstrated 1.15 W of Gaussianlike (M(2) = 2) cw output at 2.94 mum from a diode laser end-pumped monolithic laser crystal composed of Er-doped yttrium aluminum garnet (YAG) bonded to undoped YAG. The laser was pumped with two polarization-coupled 2.5-W flared laser diodes that provided a 45-mum pump waist with a low N.A. (<0.04) . Output at 2.94 mum was generated with a 34% slope efficiency and a greater-than-unity quantum efficiency.
118 citations
TL;DR: In this article, room temperature CW laser action of Yb 3+ -doped InGaAs laser diode at 1026-1044 nm has been demonstrated under pumping by 980 nm fiber-coupled InGAAs laser diodes.
115 citations
TL;DR: In this article, an array of monolithic, single-frequency-distributed-Bragg-reflector (DBR) waveguide lasers operating near 1536 nm wavelengths was demonstrated.
Abstract: We have demonstrated an array of monolithic, single-frequency-distributed-Bragg-reflector (DBR), waveguide lasers operating near 1536 nm wavelengths. The lasers were fabricated by forming waveguides in Yb/Er-codoped phosphate glass by ion exchange. The slope efficiency for each laser as a function of launched pump power is 26% and the thresholds occur at 50 mW of launched pump power. An output power of 80 mW was achieved with 350 mW of coupled pump power. Each laser exhibits stable operation on a single longitudinal mode and all have linewidths less than 500 kHz. A comb of waveguides with varying effective indices allows the selection of wavelength using a single-period grating.
102 citations
TL;DR: Room-temperature, all-solid-state, broadly tunable laser operation of Cr(2+) -doped CdSe has been demonstrated and reduced efficiency was obtained.
Abstract: Room-temperature, all-solid-state, broadly tunable laser operation of Cr2+-doped CdSe has been demonstrated. Pumping with a Q-switched Tm, Ho:YLF laser running at a 1-kHz repetition rate achieved broadband output of 500 mW at 2.6 µm with 48% absorbed power slope efficiency. With reduced efficiency, as much as 815 mW of power was obtained. With a diffraction grating, the Cr2+:CdSe laser was tuned from 2.3 to 2.9 µm with 10-nm bandwidth (FWHM) and output power up to 350 mW.
101 citations
TL;DR: In this paper, the epilayer-side mounting of a quantum cascade (QC) laser has been studied and the performance with respect to threshold current, output power, and slope efficiency is improved.
Abstract: First results on the epilayer-side mounting of quantum cascade (QC) lasers are presented. Operated in continuous-wave (CW) mode, these lasers are superior to substrate-bonded devices. The maximum CW temperature is raised by 20 K (up to 175 K), and, at comparable heat sink temperatures, the performance with respect to threshold current, output power, and slope efficiency is greatly improved for the epilayer-side mounted devices. QC-laser-specific mounting procedures are discussed in this letter, such as the high reflectivity coating of the back-facet and the front-facet cleaving after mounting. Modeling of the temperature distribution inside the QC laser shows a strong temperature gradient within the active waveguide core, which partly explains the still low maximum CW operating temperatures.
98 citations
TL;DR: In this paper, the authors reported room temperature, continuous-wave operation at 13 /spl mu/m for InGaAsN triple quantum well lasers, with a slope efficiency of 059 W/A (output per two facets).
Abstract: Room temperature, continuous-wave operation at 13 /spl mu/m is reported for InGaAsN triple quantum well lasers The layers were grown by MBE using an RF-coupled plasma source for nitrogen Large broad area lasers exhibit very low threshold current density down to 680 A/cm/sup 2/ and a slope efficiency of 059 W/A (output per two facets) Maximum output powers of 24 and 4 W are reached at 10/spl deg/C under CW and pulsed operation, respectively These values are a significant improvement over those previously published for lasers in the InGaAsN material system
90 citations
TL;DR: In this paper, a medical fiber laser oscillating at two useful wavelengths (3 and 2 /spl mu/m) was reported, and their combined output power was 3.0 W with a slope efficiency of 65%.
Abstract: A new medical fiber laser oscillating at two useful wavelengths (3 and 2 /spl mu/m) is reported. We have demonstrated highly efficient and high-power continuous-wave cascade oscillation at room temperature with a holmium ion-doped fluoride glass fiber laser pumped with a 1.15-/spl mu/m fiber Raman laser. The simultaneous oscillation wavelengths were 3 and 2 /spl mu/m, and their combined output power was 3.0 W with a slope efficiency of 65%. To our best knowledge, this is the first achievement of watt-level-output power in the mid-infrared region with ZrF/sub 4/-BaF/sub 2/-LaF/sub 3/-AlF/sub 3/-NaF (ZBLAN) glass fiber. In experiments to evaluate potential for medical applications, we tested the two wavelength beam as a laser surgical knife on soft rabbit tissues and demonstrated that it had strong cutting capability, and that the coagulation layer thickness could be controlled by varying the power ratio of the two-wavelength laser.
TL;DR: A Raman-shifted and frequency-doubled high- power Er-fiber soliton laser for seeding an efficient high-power Yb fiber femtosecond amplifier is demonstrated.
Abstract: A Raman-shifted and frequency-doubled high-power Er-fiber soliton laser for seeding an efficient high-power Yb fiber femtosecond amplifier is demonstrated. The Raman-shifted and frequency-doubled Er-soliton laser is tunable from 1.00 to 1.070 µm and produces bandwidth-limited 24-pJ pulses at a repetition rate of 50 MHz with a FWHM pulse width of 170 fs at 1.040 µm. The Yb3+ amplifier has a slope efficiency of 52% and generates 3-ps linearly chirped pulses with an average power of 0.8 W at 1.05 µm. After pulse compression, 74-fs bandwidth-limited pulses with an average power of 0.4 W and a pulse energy of 8 nJ are generated.
TL;DR: In this article, a closed-form model was developed to characterize the spectral and spatial portions of amplified spontaneous emission in a flashlamp-pumped Nd:YAG laser with a threshold of 12 J and a slope efficiency of 0009.
Abstract: Amplified spontaneous emission can seriously degrade the Q-switched performance of a strong four-level transition such as the 1064 /spl mu/m Nd:YAG transition or can even prevent oscillation on a weaker quasi-four-level transition such as the 0946-/spl mu/m Nd:YAG transition To characterize, and thus be able to mitigate, amplified spontaneous emission, a closed-form model is developed By employing a closed-form solution, the differential equations describing both the evolution and decay of the upper laser manifold population density can be solved exactly An advantage of this model is the separation of the spectral and spatial portions of amplified spontaneous emission Gain measurements, as a function of time and pump energy, are compared with the model and good agreement is found With these principles in mind, a flashlamp-pumped Nd:YAG laser was designed to operate at 0936 /spl mu/m At room temperature, a threshold of 12 J and a slope efficiency of 0009 was achieved
TL;DR: In this paper, the thermal expansion coefficients along a- and c-axis are α 1 = 2.2 × 10 -6 /K, and α 3 = 8.4 × 10 −6/K respectively.
Abstract: Nd:YVO 4 crystal has been grown by Czochralski method. The data of thermal expansion and specific heat have been measured. The thermal expansion coefficients along a- and c-axis are α 1 = 2.2 × 10 -6 /K, and α 3 = 8.4 × 10 -6 /K respectively. The specific heat is 24.6 cal/mol K at 330 K. The large anisotropy along c- and a-axis of thermal expansion coefficients is explained by the structure of YVO 4 crystal. 921 mW output laser at 1.06 μm has been obtained with a 3 mm × 3 mm × 1 mm crystal sample when pumped by 1840 mW cw laser diode, and the slope efficiency is 55.5%.
TL;DR: In this article, a diode-pumped, self-frequency doubling (SFD) laser crystal Nd3+:YCa4O(BO3)3 was developed with a slope efficiency of 51%.
Abstract: We report efficient, diode-pumped, self-frequency doubling (SFD) in the newly developed laser crystal Nd3+:YCa4O(BO3)3. More than 350 mW of fundamental output power at 1060 nm was achieved with a slope efficiency of 51%. With one watt of absorbed pump power, 62 mW of green cw laser emission at 530 nm was observed with proper phase matching. This initial performance, and the good optical properties of the crystalline host, are encouraging for the development of a high power diode-pumped SFD visible light laser source.
TL;DR: An all-fiber 1.48-mum generator based on a laser-diode-pumped Yb-doped double-clad laser and a cascaded Raman wavelength converter and second-order Raman Stokes radiation was generated in a phosphosilicate-f fiber resonator formed by two pairs of Bragg gratings.
Abstract: An all-fiber 1.48?µm generator based on a laser-diode-pumped Yb-doped double-clad laser and a cascaded Raman wavelength converter has been developed. Second-order Raman Stokes radiation was generated in a phosphosilicate-fiber resonator formed by two pairs of Bragg gratings. A slope efficiency of the Raman converter of 48% with respect to the power emitted by the double-clad Yb laser has been achieved. We obtained an output power of 1 W at a slope efficiency of 34% with respect to the laser-diode array power, with a total optical-to-optical efficiency of 23%.
TL;DR: In this paper, a 3-W CW laser-diode pumping was used to obtain a 760 mW 2.01 μm Tm:YAG laser under CW operation.
Abstract: Eye-safe solid-state lasers that operate at 2 μm wavelength have many applications in medical, remote sensing and military technologies. With a 3-W CW laser-diode pumping, we obtained 760 mW 2.01 μm Tm:YAG laser under CW operation. The slope efficiency was 44% and the optical to optical efficiency reached 36%. In the acousto-optic Q-switched operation, laser pulses with the energy of 1.2mJ and 380 ns FWHM width have been achieved.
TL;DR: In this article, an experimental study of the influence of the Nd 3+ concentration on scaling diode-pumped Nd:YVO 4 1.34 μm laser to higher power was conducted.
TL;DR: In this article, the laser action of the Yb:YCOB crystal has been demonstrated when it is pumped by a fiber-coupled laser diode at the wavelength of 976.4nm.
Abstract: Yb:Ca4YO(BO3)3 (Yb:YCOB) crystal with good quality and large size has been grown by the Czochralski method. The polarization absorption and fluorescence spectra have been measured. The laser action of the Yb:YCOB crystal has been demonstrated when it is pumped by a fiber-coupled laser diode (LD) at the wavelength of 976.4 nm. The pumping threshold is 55 mW, the light-light conversion efficiency is 58.7%, and a slope efficiency of up to 73% is thus calculated.
TL;DR: In this article, the distribution coefficient of Ce 3+ was determined to be 0.01, and a foreign material adhering to the surface of the crystals was investigated, which indicated that the material was not a foreign substance.
TL;DR: In this article, the authors investigate loss mechanisms in 1.55-/spl mu/m InGaAsP-InP multiquantum-well ridge-waveguide laser diodes at room temperature.
Abstract: We investigate loss mechanisms in 1.55-/spl mu/m InGaAsP-InP multiquantum-well ridge-waveguide laser diodes at room temperature. The common method of measuring light versus current curves and plotting the inverse slope efficiency versus laser length is employed to extract the internal optical loss /spl alpha//sub i/ and the differential internal efficiency /spl eta/. This method neglects the dependence of both the parameters on the laser cavity length L. We analyze physical mechanisms behind these loss parameters and their length dependence using the commercial laser simulation software PICS3D. Internal optical losses are dominated by carrier density dependent absorption. The differential internal efficiency above threshold is found to be mainly restricted by carrier recombination losses within the quantum wells, i.e., Fermi level pinning is not observed. Both loss mechanisms are enhanced with shorter cavity length due to the higher quantum well carrier density. For the shortest device measured (L=269 /spl mu/m), we extract /spl alpha//sub i/=20 cm/sup -1/ and /spl eta//sub i/=66%. With increasing cavity length, the loss parameters approach /spl alpha//sub i/=15 cm/sup -1/ and /spl eta//sub i/=70%. From the inverse slope efficiency versus cavity length plot, we obtain /spl alpha//sub i/=14 cm/sup -1/ and /spl eta//sub i/=67% independent of laser length.
TL;DR: In this article, a diode-laser-array end-pumped efficient CW Nd:GdVO4 laser at 1.06μm has been developed, achieving an optical conversion efficiency of 55% and an average slope efficiency of 62%.
Abstract: A diode-laser-array end-pumped efficient CW Nd:GdVO4 laser at 1.06 μm has been developed. A low-order-mode output power of 14.3 W was obtained at the maximum available pump power of 26 W, giving an optical conversion efficiency of 55% and an average slope efficiency of 62%. The laser output beam quality factor at full pump power was determined to be M2<1.8. It is also shown that only lightly doped Nd:GdVO4 crystals are suitable for high-power end-pumped lasers.
Patent•
25 Jan 1999
TL;DR: In this article, a vertical cavity surface emitting laser (VCSEL) with variable tuning layer for adjusting the slope of the laser and method for manufacturing the same are disclosed, where an optical subassembly and optical transceiver incorporating the improved VCSELs are also disclosed.
Abstract: A vertical cavity surface emitting laser (VCSEL) with variable tuning layer for adjusting the slope of the laser and method for manufacturing the same are disclosed. In practice, a VCSEL wafer is grown by any conventional technique, and fabricated into discrete lasers while maintained in wafer form. The initial lasers are then tested to determine characteristics, such as the slope efficiency distribution. A variable thickness dielectric layer is then deposited which is calculated to tune the slope efficiency distribution to within a target specification by altering the phase of the top facet reflectivity of the initial lasers. The resulting change in transmission directly changes the laser slope in a predictable fashion. The tuning step may be repeated, if necessary, to further refine the slope to the desired value. The method produces VCSELs with similar or consistent slopes from a plurality of wafers. Also disclosed are an optical subassembly and optical transceiver incorporating the improved VCSELs.
TL;DR: The laser performance of bulk samples with various ErF(3) contents was investigated with respect to the optimum doping concentration, which is estimated to be higher than 8 mol.
Abstract: We report on the laser emission of erbium-doped fluoride glasses in the spectral range from 2.7 to 2.8 mum . The pump source was a fiber-coupled InGaAs semiconductor laser emitting near lambda(p)~970 nm . The laser performance of bulk samples with various ErF(3) contents was investigated with respect to the optimum doping concentration, which is estimated to be higher than 8 mol. %. A maximum output power of P(out) > 160 mW and a slope efficiency of eta = 10% were achieved. Results are compared with previously published data on erbium-doped ZBLAN fiber and LiYF(4) crystal lasers.
TL;DR: Tunability of the Yb:GdCOB laser from 1035 to 1088 nm with a 1.7% output coupler and 100-nm tunability with a low-transmission output coupling is achieved and temperature does not significantly affect the laser performance.
Abstract: A
Yb3+:Ca4GdO(BO3)3
(Yb:GdCOB) crystal has been diode pumped for the first time to our
knowledge. We obtained 47.5% slope efficiency at 6 °C,
producing 191 mW of power at 1050 nm, with a 2.4% output
coupler. Temperature does not significantly affect the laser
performance: At room temperature we still obtained 180 mW of power
for the same cavity. We achieved tunability of the Yb:GdCOB laser
from 1035 to 1088 nm with a 1.7% output coupler and 100-nm tunability
with a low-transmission output coupling (T =
0.03%).
TL;DR: A novel short-length diode-pumped cw fiber laser with high output power at a wavelength of 2.8mum is reported, which combines continuous-wave diode pumping at 970 nm, a high doping concentration, and an annular geometry of the laser medium, an M-profile fiber.
Abstract: We report a novel short-length diode-pumped cw fiber laser with high output power at a wavelength of 2.8 µm. The system combines continuous-wave diode pumping at 970 nm, a high doping concentration (5-mol.?% ErF3) of the active fiber, and an annular geometry of the laser medium, an M-profile fiber. Output powers in excess of 1 W with a slope efficiency of 25% were obtained.
TL;DR: In this paper, a ytterbium-doped, glass, channel waveguide laser, fabricated by ion exchange, is reported, using broad-band 4% output couplers, lased in the vicinity from 1020 to 1030 nm when pumped by a Ti:sapphire laser operating at 910 nm.
Abstract: A ytterbium-doped, glass, channel waveguide laser, fabricated by ion exchange, is reported. The 2.2 cm long device, using broad-band 4% output couplers, lased in the vicinity from 1020 to 1030 nm when pumped by a Ti:sapphire laser operating at 910 nm. A lasing threshold of 50 mW (launched pump) and a slope efficiency of 5% were measured. Device parameters, including fluorescence lifetimes, emission and absorption cross sections, propagation losses, and mode profiles were experimentally determined and laser performance was analytically modeled using this data.
TL;DR: In this article, the laser performance of a range of solid state dye lasers based on rhodamine 590-doped co-polymers of 2-hydroxyethyl methacrylate (HEMA) and MPMMA has been investigated.
TL;DR: In this paper, the authors show that high internal quantum efficiency and low internal loss results in very high slope efficiency at a long cavity length, and consequently, extremely high total power conversion efficiency at high continuous-wave power output.
Abstract: 808 nm lasers grown by molecular beam epitaxy show extremely high internal quantum efficiency and low internal loss, which results in very high slope efficiency at a long cavity length, and consequently, extremely high total power conversion efficiency at high continuous-wave power output.
TL;DR: In this article, the authors investigated the continuous-wave power performance of an efficient diode-pumped Nd:YVO 4 laser at 1342 nm by employing four different end pumping configurations.