ABSTRACT
We present, to the best of our knowledge, the most efficient solid-state laser directly emitting in the yellow spectral range. Without any nonlinear conversion steps, a Tb3+:LiLuF4 laser operates at a wavelength of 587.5 nm with an output power of 0.5 W and a record-high slope efficiency of 25% with respect to the absorbed pump power at 486.2 nm. Despite the detrimental influence of 4f-excited state absorption, this efficiency is comparable to those obtained by complex nonlinear methods to generate yellow laser emission. Our approach, in combination with the progress in laser diodes at the required pump wavelength, paves the way for the development of cost-efficient, robust, and easily manageable diode-pumped yellow laser sources.
ABSTRACT
Eu3+-doped LiYF4 is reexamined as a laser material for the visible spectral region. Polarized absorption and emission cross sections as well as the fluorescence lifetime are determined. Branching ratios and radiative lifetime are calculated within the theory of 4f-4f transition intensities, which takes into account the influence of an excited configuration of the opposite parity 4fN-15d. Continuous-wave laser operation at 702 nm is demonstrated with a maximum output power of 15 mW and a slope efficiency of 4.6% under pumping with a frequency-doubled Ti:sapphire laser at 393.5 nm.
ABSTRACT
We report on a 2ω-OPSL-pumped passively Q-switched Pr3+:LiYF4 laser operating at the wavelengths of 523, 607, and 640 nm. For this, we utilized a Co2+-doped MgAl2O4 (MALO) crystal as a saturable absorber in the visible range for the first time, to the best of our knowledge. In the green spectral region, the pulse duration was 210 ns with a pulse energy of 3.6 µJ and a repetition rate of 125 kHz. The minimum pulse duration of 87 ns at the highest pulse energy of 8.6 µJ was obtained at a repetition rate of 110 kHz at 607 nm. The highest Q-switched average laser power of 1.4 W was obtained at an absorbed continuous-wave pump power of 3.3 W with a slope efficiency of 47% at 640 nm. Absorption saturation measurements with Co:MALO were performed, and ground and excited state absorption cross sections in the visible spectral range were determined.
ABSTRACT
An investigation of Tm-Ho energy transfer in Tm(5at.%),Ho(0.4at.%):KYW single crystal by two independent techiques was performed. Based on fluorescence dynamics measurements, energy transfer parameters P71 and P28 for direct (TmâHo) and back (HoâTm) transfers, respectively, as well as equilibrium constant Θ were evaluated. The obtained results were supported by calculation of microscopic interaction parameters according to the Förster-Dexter theory for a dipole-dipole interaction. Diode-pumped continuous-wave operation of Tm,Ho:KYW microchip laser was demonstrated, for the first time to our knowledge. Maximum output power of 77 mW at 2070 nm was achieved at the fundamental TEM00 mode.
