High-power and highly efficient Tm3+-doped silica fiber lasers pumped with diode lasers operating at 1150 nm

An output power of 1.74 W at 2.03 microm was generated at a slope efficiency of 51% when a double-clad Tm(3+)-doped silica fiber laser was pumped with high-power 1150 nm diode lasers. Pump excited state absorption from the upper laser level populates higher energy levels allowing cross relaxation to repopulate the upper laser level at a quantum efficiency greater than unity and to limit losses relating to additional pump excited state absorption. The output power was scaled to 4.77 W when both ends of the fiber were pumped.     

Visible cw laser emission of GaN-diode pumped Pr:YAlO3 crystal

In the present work we report on spectroscopic properties and laser results of GaN laser diode pumped Pr:YAlO₃ crystal at room temperature. The polarization-resolved absorption and emission spectra have been recorded and the decay time of the ³ P ₀ manifold has been measured. Three samples with different Pr³⁺-ion concentrations in YAP matrix have been tested and compared. The best results were achieved for 0.6 at. % Pr³⁺-ion doping: an output power of 91 mW at 746.9-nm wavelength with a maximum slope efficiency of 45% with respect to the absorbed power.     

Diode pumping of a continuous-wave Pr3+-doped LiYF4 laser

We report, for the first time to our knowledge, diode-pumped cw laser oscillation of Pr3+:LiYF4 in the red spectral range. The pump power is provided by a GaN laser diode emitting a maximum output power of 25 mW at a wavelength of approximately 442 nm. The Pr3+ laser emits 1.8 mW of output power at a 639.7-nm wavelength. Threshold pump power and slope efficiency in a nonoptimized setup are determined to be 5.5 mW and 24%, respectively.     

High-power GaN diode-pumped continuous wave Pr3+-doped LiYF4 laser

A cw Pr(3+):LiYF(4) laser at 639 nm pumped by a high-power GaN laser diode (444 nm) is demonstrated. The highest laser power of 112 mW is achieved with an optical-optical conversion efficiency of 33.5%. Characteristics of this laser at elevated temperatures are also investigated for practical applications such as a laser projector.     

Low threshold Nd3+:KY(WO4)2 laser operated at 1072 nm pumped by diode

The diode-pumped Nd:KYW laser operated in the free-running mode at 1072 nm is demonstrated at room temperature. The laser output power of 102.6 mW with 12.07% optical-to-optical conversion efficiency and 13.16% slope efficiency is obtained.     

Orange,red and deep-red flashlamp-pumped Pr3+:LiYF4 laser with improved output energy and efficiency

Three laser transitions (607.2 nm, 639.5 nm, 720.9 nm) in a flashlamp-pumped Pr³⁺:LiYF₄ laser at room temperature are investigated. Cerium ions (Ce³⁺) doped into the fused-quartz envelope of the flashlamp efficiently transfer strong UV radiation from pumping light into the absorption region of Pr³⁺ ions ( = 420–480 nm), so that the slope efficiency of all three laser emissions could be increased by almost 100% compared to excitation with a pure quartz flashlamp. At a pump energy of 30 J the output energy of these three laser emissions reached 4.7 mJ, 87 mJ and 30 mJ.     

Optical transitions of Pr3+ and Er3+ ions in LiYF4

The optical absorption, emission, and excitation spectra of Pr³⁺ and Er³⁺ ions in LiYF₄ have been measured and energy level schemes established which agree with previous work. The temperature dependence of the emission lifetimes were investigated and analyzed using the Huang-Rhys and Struck-Fonger treatments of multiphonon decay. The non-radiative processes in LiYF₄: Er³⁺ were shown to follow the same “gap law” behavior as Er³⁺ in LaF₃ and MnF₂. Theoretical fits to the Huang-Rhys model allowed the construction of a configuration coordinate diagram for the Er³⁺ system. The non-exponential temperature dependence of the ¹D₂ lifetime in Pr³⁺ can be understood as a non-radiative transition from higher levels.     

High power continues wave laser diode array end pumped Nd:YAG/LBO red lasers operated at 669 nm and 659 nm

In this paper, we present using Nd:YAG as the laser media, and Brewster plate as a polarizer device to obtain the linear polarization output at the fundamental wavelength. Using LBO (LiB₃O₅) crystal as non-linear crystal to obtain intra-cavity frequency doubled red laser at 659 and 669 nm and sum frequency mixing at 665 nm. Using a thin fused silica plate as an etalon to obtain the single wavelength operation. At total pump power of 30 W at 808 nm, the output powers at two wavelengths are about 4.1 and 4.5 W, respectively, only one fundamental wavelength light is resonating. The corresponding optical to optical conversion efficiency from pump light to second harmonic generation are 13.7 and 15.0%, respectively.     

494 nm blue laser based on sum-frequency mixing of diode pumped Nd<Superscript>3+</Superscript> lasers

We report for the first time a continuous-wave (CW) blue radiation at 494 nm by intracavity sumfrequency generation of 912 nm Nd:GdVO₄ laser and 1079 nm Nd:YAlO₃ (Nd:YAP) laser. Using type-I critical phase matching LiB₃O₅ (LBO) crystal, 494 nm blue laser was obtained by 912 and 1079 nm intra-cavity sum-frequency mixing, and output power of 179 mW was demonstrated. At the output power level of 179 mW, the output power stability is better than 3.5% and laser beam quality M ₂ factor is 1.21.     

504 nm blue-green laser based on sum-frequency mixing of diode pumped Nd<Superscript>3+</Superscript> lasers

We report for the first time a continuous-wave (CW) blue-green radiation at 504 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser and 1080 nm Nd:YAlO₃ (Nd:YAP) laser. Using type-I critical phase matching LiB₃O₅ (LBO) crystal, 504 nm blue-green laser was obtained by 946 and 1080 nm intra-cavity sum-frequency mixing, and output power of 215 mW was demonstrated. At the output power level of 215 mW, the output power stability is better than 4.7% and laser beam quality M² factor is 1.21.     

Laser diode and pumped Cr:Yag passively Q-switched yellow-green laser at 543 nm

Efficient and compact yellow green pulsed laser output at 543 nm is generated by frequency doubling of a passively Q-switched end diode-pumped Nd:YVO₄ laser at 1086 nm under the condition of sup-pressing the higher gain transition near 1064 nm. With 15 W of diode pump power and the frequency doubling crystal LBO, as high as 1.58 W output power at 543 nm is achieved. The optical to optical conversion efficiency from the corresponding Q-switched fundamental output to the yellow green output is 49%. The peak power of the Q-switched yellow green pulse laser is up to 30 kW with 5 ns pulse duration. The output power stability over 8 hours is better than 2.56% at the maximum output power. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by frequency doubling of a passively Q-switched end diode pumped Nd:YVO₄ laser at 1086 nm.     

Highly efficient Tm:YAG ceramic laser resonantly pumped at 1617 nm

We report on a highly efficient polycrystalline Tm:YAG ceramic laser in-band pumped by an Er:YAG laser at 1617 nm. Lasing characteristics of 4.0 and 6.0 at.%Tm(3+)-doped YAG ceramics were investigated and compared. With an output coupler of 10% transmission, a maximum output power of 7.3 W was obtained at 2015 nm under 12.8 W of incident pump power, corresponding to a slope efficiency with respect to incident pump power of 62.3%.     

Vacuum ultraviolet gain measurements in optically pumped LiYF4:Nd3+

 We present measurements of the net-induced gain on the 5d–4f transition at 186 nm in LiYF₄ : Nd³⁺ optically pumped by radiation from a molecular fluorine laser. It is found that for LiYF₄ : Nd³⁺, one of a series of potential continuously tunable VUV lasers, relatively strong excited-state absorption results in net-induced loss. The prospects for VUV laser operation being realised in other rare-earth-doped fluorides is discussed. Received: 4 March 1996/Revised version: 10 July 1996     

Q-switch operation of a c-cut 2132-nm Tm, Ho:YAP laser pumped by a laser diode of 794.3 nm

Q-switch operation of a c-cut Tm (5 at %), Ho (0.3 at %):YAP laser at 2132 nm wavelength were reported in this paper. In the temperature of 77 K, the Tm, Ho:YAP crystal was double end-pumped by a 21.4-W fiber-coupled laser diode (LD) at the center wavelength of 794.3 nm. A 5.29-W Q-switch output power was acquired at pulse repetition frequency (PRF) of 10 kHz, corresponding to an optical-optical conversion efficiency of 24.7% and a slope efficiency of 28.1%. The energy per pulse of 3.57 mJ in 38 ns was achieved at 1.25 kHz with the peak power of 93.9 kW.     

CW green laser at 520 nm based on sum-frequency mixing of diode pumped Yb:YAG laser

We report for the first time a continuous-wave (CW) green laser emission by sum-frequency mixing in Yb:YAG crystal. Using type-I critical phase-matching LBO crystal, a green laser at 520 nm is obtained by 1030 and 1048 nm intracavity sum-frequency mixing. The maximum laser output power of 269 mW is obtained when an incident pump laser of 17.8 W is used. At the output power level of 269 mW, the output stability is better than 3.2%.     

Highly efficient CW intracavity frequency-doubled Yb:YAG-LBO laser at 515 nm under 968 nm diode laser pumping

We describe the output performances of the 1030 nm transition in Yb:YAG under in-band pumping with diode laser at the 968 nm wavelength. An end-pumped Yb:YAG crystal yielded 1.93 W of continuous-wave (CW) output power for 9.1 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 23.6%. Furthermore, 205 mW 515 nm green light was acquired by frequency doubling, resulting in an optical-to-optical efficiency with respect to the absorbed pump power of 2.7%. Comparative results obtained for the pump with diode laser at 940 nm are given in order to prove the advantages of the in-band pumping.     

Pulsed Nd:YAP laser at 1432 nm pumped with high power laser diode

LD end pumped Nd:YAP laser operation in the eye safe spectrum region at 1432 nm is reported. With pump energy of 256 mJ, maximum linearly polarized output of 26 mJ is obtained. The optical-to-optical overall efficiency is around 10%, and the slope efficiency is around 18%. The laser beam operates with spiking mode with a total emission period of less than 300 µs at 10 Hz. The stimulated emission cross section is estimated at around 0.85 × 10^− 20 cm².     

Quasi-three-level Nd:YVO<Subscript>4</Subscript> laser operation at 914 nm under 879 nm diode laser pumping

We present experimental investigation on quasi-three-level Nd:YVO₄ laser operation at 914 nm under 879 nm diode pumping directly into emitting level. A maximal output power of 3.0 W under an absorbed pump power of 13.4 W was got, corresponding to an optical conversion efficiency of 22.4% and a slope efficiency of 40.3%. To the best of our knowledge, this is the first report on a Nd:YVO₄ laser at 914 nm using rod-type single crystal as the gain medium and end pumped by diode directly into the emitting level.     

1064 nm Nd:YVO4 laser intracavity pumped at 912 nm and sum-frequency mixing for an emission at 491 nm

We present for the first time a Nd:YVO(4) laser emitting at 1064 nm intracavity pumped at 912 nm by a Nd:GdVO(4) laser. We carried out a model to design the system properly, and laser performance was experimentally investigated. Intracavity sum-frequency mixing at 912 and 1064 nm was then realized in a BiBO crystal to reach the blue range. We obtained a cw output power of 155 mW at 491 nm with a pump laser diode emitting 20 W at 808 nm.