Francesca Moglia

High-power red, orange, and green Pr 3+ :LiYF 4 lasers

Laser experiments with Pr(3+):LiYF4 under excitation with a frequency doubled optically pumped semiconductor laser emitting 5 W at 479 nm were performed at seven different laser wavelengths of 523, 546, 604, 607, 640, 698, and 720 nm. At all these wavelengths the output power exceeded 1 W. The best performance at 523 nm with an output power of 2.9 W at a slope efficiency of 72% and an optical-to-optical efficiency of 67% with respect to the incident pump power represents the highest efficiency ever reported for a praseodymium-doped laser material.

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.

Wide wavelength tunability and green laser operation of diode-pumped Pr 3+ :KY 3 F 10

We report on wide spectral tunability of a quasi-continuous wave Pr(3+):KY(3)F(10) laser under InGaN laser diode excitation at 445 nm. The total tuning range exceeded 100 nm in the visible spectral range on several intervals between 521 nm and 737 nm. The broadest continuously tunable region of almost 50 nm extended from 688 nm to 737 nm. Furthermore we present what is to the best of our knowledge the first demonstration of continuous wave laser operation in Pr(3+):KY(3)F(10) on three transitions in the green spectral region. The highest output power of 121 mW was achieved at an emission wavelength of 554 nm with a slope efficiency of 27%.

Prospects of Holmium-doped fluorides as gain media for visible solid state lasers

In this paper we report on the suitability of Ho3+:LiLuF4 and Ho3+:LaF3 as active media for solid state lasers emitting in the green spectral region. The ground state absorption spectra were measured and employed to calculate the emission cross section spectra via the reciprocity method. These allowed to derive the gain characteristics for various inversion ratios. The decay dynamics of the 5F4,5S2 multiplet, which would act as upper laser level, were investigated to estimate the quantum efficiency. Measurements of the excited state absorption were conducted which showed that stimulated emission is the dominating effect around 550 nm. Laser operation was demonstrated in the green spectral region by employing Ho3+:LaF3 as gain medium. Laser oscillation occurred in a self-pulsed regime with a maximum average output power of 7.7 mW, a repetition rate of 5.3 kHz, and a pulse duration of 1.6 μs. To the best of our knowledge this constitutes the first green laser emission of a Ho3+-doped crystal at room temperature.

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].

Photoluminescence of (YGd)2O3:Eu phosphors produced by nanoparticle-seeded flame-assisted spray pyrolysis

We report on synthesis of europium-doped (Y1?xGdx)2O3 by flame-assisted spray py-rolysis in premixed propane/air flames. Phosphor powders with an average particle size on the order of 0.5 ?m were obtained from 0.2 M aqueous solutions of the corresponding metal salts. Relative concentration of gadolinium (x) was varied in the range 0 to 1. For excitation at a wavelength of 254 nm, the highest intensity of photoluminescence was achieved for x = 0.2 (110% of brightness of the samples without gadolinia). Doping pure yttria and gadolinia with nanoparticles of Y2O3:Eu (dBET = 24 nm) was tested. Addition of nanoseeds (up to 50 mol.% in the obtained powders) noticeably decreased surface roughness of phosphor particles.

Er:LiLuF 4 upconversion waveguide laser with femtosecond-laser written circular cladding structures

The common scheme of femtosecond-laser inscription of waveguides in fluorides is a cladding geometry. The first crystalline Er:LiLuF4-upconversion waveguide laser is reported somewhere else. The poor stability and efficiency of the green emission were caused by nonoptimized cavity and fabrication parameters. In this paper, the mentioned drawbacks were tried to be overcome and an improvement in stability and output power is shown by the application of a circular cladding geometry. An output power of 10 mW at 552.6 nm could be achieved, with an incident pump power on the crystal of 1.5 W at 974 nm.

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

In this paper, we present spectroscopic investigations and first diode pumped quasi continuous wave (qcw) laser oscillation of Pr³⁺:LaF₃ in the visible spectral range.

Er3+:LaF3 as Potential Material for Upconversion Lasers

We have grown an Er3+:LaF3 crystal and present the spectroscopic analysis in order to confirm the possibility to realize an excited state absorption pumped upconversion laser in the green spectral range via near-infrared pumping.

Diode Pumped Laser Oscillation at 750 nm and Excited State Absorption Measurements of Ho 3+ :LiLuF 4

We present the first demonstration of laser oscillation of Ho3+:LiLuF4 in the visible spectral range. Furthermore, we investigated the spectroscopic properties with regard to its potential as an active medium for diode pumped solid state lasers.