Nils-Owe Hansen

Efficient green continuous-wave lasing of blue-diode-pumped solid-state lasers based on praseodymium-doped LiYF4.

We report highly efficient laser operation of praseodymium-doped LiYF(4) in the green spectral range. The influence of the crystal length and pump light focusing on the laser performance has been studied. The pump radiation was delivered by InGaN laser diodes. Optimizing the setup for a 2.9 mm long crystal with a doping concentration of 0.5% led to an electric to green laser power conversion efficiency as high as 7.4%. With 500 and 1000 mW of pump light power, output powers of 179 and 358 mW have been reached, respectively. With respect to absorbed power, slope efficiencies of up to approximately 60% have been achieved.

Femtosecond-laser-written diode-pumped Pr:LiYF 4 waveguide laser

Waveguides were fabricated in a 5 mm long Pr(0.5 at%):LiYF4 (YLF) crystal with a femtosecond Ti:sapphire laser system. Waveguiding was achieved inside a core surrounded by eight single modified tracks building a rhombic structure. The waveguide was pumped at a wavelength of 444 nm with an InGaN laser diode. Orange and deep red laser oscillation were realized. Maximum output powers of 25 mW at 604 nm and 12 mW at 720 nm with respect to the incident pump power were achieved.

Crystalline Pr:SrAl 12 O 19 waveguide laser in the visible spectral region

We fabricated waveguides in Pr:SrAl(12)O(19) crystals by direct femtosecond laser writing. The propagation losses were calculated to be as low as 0.16 dB/cm at a wavelength of 633 nm. Laser oscillation in a diode-pumped waveguide at a wavelength of 643.5 nm was realized. The output power of the waveguide laser was 28.1 mW at a slope efficiency of 8%.

Diode pumped laser operation and spectroscopy of Pr 3+ :LaF 3

We report on the first results of diode pumped laser operation of Pr3+:LaF3 in a quasi continuous wave (qcw) mode with average output powers of up to 80.0 mW (≈ 161.3 mW qcw) and a maximum slope efficiency of 37% at 719.8 nm. Furthermore it was possible to operate the laser at 537.1 nm and 635.4 nm and to tune the emission wavelength from 609 nm to 623 nm. The pump source was an InGaN laser diode with a maximum output power of 1 W at a central emission wavelength of 442 nm.

Efficient laser operation of Pr 3+ , Mg 2+ :SrAl 12 O 19

In this Letter, we report on laser operation of Pr3+,Mg2+:SrAl12O19 pumped by a frequency-doubled optically pumped semiconductor laser. By employing a V-type cavity, we demonstrate cw laser operation at room temperature in the green spectral range in a doped oxide host for the first time to the best of our knowledge. Furthermore, efficient laser operation was realized in the orange, red, and deep red spectral range with output powers exceeding 1.1 W at emission wavelengths of 643.6 and 724.4 nm.

First ceramic laser in the visible spectral range

Results for new fluoride ceramics doped with praseodymium ions in which, to the best of our knowledge, for the first time a laser in the visible spectral range (639 nm) was obtained under GaInN blue laser diode optical pumping. In our experiments, CW operation with lasing threshold less than 100 mW of absorbed pump power and slope efficiency exceeding 9% was realized.

Novel rare earth solid state lasers with emission wavelengths in the visible spectral range

Recent developments in blue emitting laser sources, in particular InGaN laser diodes (InGaN-LDs) and frequency doubled optically pumped semiconductor lasers (2ω-OPSLs), opened access both to visible laser operation with unprecedented efficiencies in the well-established praseodymium doped laser systems [1, 2] as well as to the realization of new rare earth based solid state laser systems with emission wavelengths in the visible spectral range [3].

New Visible SrF2:Pr3+ Ceramic Laser at 639 nm

For the first time to our knowledge SrF2:Pr3+ fluoride ceramics was developed and visible 639 nm wavelength oscillations were obtained in diode pumped CW mode with slope efficiency above 9%.

First visible 639 nm SrF 2 :Pr 3+ ceramic laser

During the last years the interest for RE doped fluoride ceramics has arisen due to its improved thermo mechanical properties compared to analogous single crystal. Within short period of time number of fluoride nanoceramics were developed and rather efficient diode pumped lasing was demonstrated for LiF:F<inf>2</inf>⁻ [1], CaF<inf>2</inf>-SrF<inf>2</inf>:Yb³⁺ [2], CaF<inf>2</inf>:Yb³⁺ [3], SrF<inf>2</inf>:Nd³⁺ [4]. The common feature for all these ceramics was that laser oscillations in near IR spectral region 1–1.2 µm were obtained. It is well known that the optical losses in ceramic host material (scattering on grain boundaries, pores and inclusions) should strongly increase at shorter wavelengths. From this point of view the development and the investigation of laser ceramics which can oscillate at visible wavelengths is of great important. The recent success in visible light generation with Pr³⁺ ions [5] has become possible due to development of efficient blue GaInN diodes. In this work the results on oscillation properties of new Pr³⁺ doped SrF<inf>2</inf> ceramics are firstly presented.

Continuous wave Pr 3+ :LuAlO 3 laser in the visible range

We report to the best of our knowledge the first demonstration of a continuous wave (cw) Pr3+:LuAlO3 laser. So far, only pulsed laser action has been shown [1]. Extensive spectroscopic investigations have been performed on this material in the course of scintillator research [2]. But the trivalent praseodymium ion is also interesting for visible solid-state lasers because of its energy level scheme enabling several transitions in the red, orange, green, and blue spectral range. In fluorides like LiYF4 efficient laser action has been realised, which is of interest for display applications [3,4]. However, oxides provide better mechanical and chemical properties and are easier to fabricate, mostly at lower costs. LuAlO3 is a suitable oxidic host for a Praseodymium laser due to its energetically high lying 5d-levels [5], which are the final states of detrimental excited-state-absorption that prevents laser action.