S-FAP Laser Research Articles

Efficient blue emission of ytterbium-doped Sr5(PO4)3F under quasi-three-level intracavity pumping

We report an Yb:Sr5(PO4)3F (Yb:S-FAP) laser emitting at 985 nm intracavity pumped by a 912 nm diode-pumped Nd:GdVO4 laser. A 808 nm diode laser is used to pump the Nd:GdVO4 crystal emitting at 912 nm, and the Yb:S-FAP laser emitting at 985 nm intracavity pumped at 912 nm. With incident pump power of 17.5 W, intracavity second harmonic generation has been demonstrated with a power of 131 mW at 492.5 nm by using a LBO nonlinear crystal.

Comparison of Nd:phosphate glass, Yb:YAG and Yb:S-FAP laser beamlines for laser inertial fusion energy (LIFE) [Invited

We present the results of performance modeling of diode-pumped solid state laser beamlines designed for use in Laser Inertial Fusion Energy (LIFE) power plants. Our modeling quantifies the efficiency increases that can be obtained by increasing peak diode power and reducing pump-pulse duration, to reduce decay losses. At the same efficiency, beamlines that use laser slabs of Yb:YAG or Yb:S-FAP require lower diode power than beamlines that use laser slabs of Nd:phosphate glass, since Yb:YAG and Yb:S-FAP have longer storage lifetimes. Beamlines using Yb:YAG attain their highest efficiency at a temperature of about 200K. Beamlines using Nd:phosphate glass or Yb:S-FAP attain high efficiency at or near room temperature.

Diode-pumped Nd:YVO_4/Yb:S-FAP laser emitting at 985 and 4925 nm

For the first time, to the best of our knowledge, Yb:S-FAP crystals have been intracavity pumped by a Nd:YVO(4) laser at 914 nm. This original pumping scheme allows efficient laser action on the three-level transition at 985 nm with 1.4 W output power. Second-harmonic generation is also presented with a total output power of 120 mW at 492.5 nm.

Three-level operation of a diode-bar-pumped Yb:S-FAP laser

We present an all solid-state Yb:S-FAP laser system running on the three-level laser transition at 985 nm. The pump source was a high fill-factor laser diode bar, with the output reformatted using a two-mirror beamshaping system to produce a rectangular pump beam that focused to a square spot. A nearly on-axis multipassing system was used to obtain four pump passes through a 1.6 mm Yb:S-FAP laser crystal. Gain-switched three-level laser output was achieved with an efficiency of 4.3% with respect to incident pump power. Electro-optic Q-switching produced 0.12 mJ pulses for a pump pulse energy of 11 mJ. Intra-cavity second-harmonic generation yielded a maximum pulse energy at 492.5 nm of 12 μJ.

Diode-pumped, chirped-pulse Yb:S-FAP regenerative amplifier for laser-Compton X-ray generation

We present a diode-pumped, chirped-pulse Yb:S-FAP regenerative amplifier. This regenerative amplifier was developed as a first amplifier in an all-solid-state Yb:S-FAP laser system for laser-Compton X-ray generation. The amplifier delivers pulse energies above 24mJ at a repetition rate of 50Hz. Pulse compression reduces pulse widths to approximately 2.0ps.

Asymmetric beam shaping of a diode-bar laser for multipass pumping of a thin-crystal laser

Two-mirror beam shaping of a 94% fill-factor laser diode bar was investigated. We show that optimal output for the purposes of end pumping was achieved by configuring the beam shaper to reformat the single row of 60 emitters into an array containing several emitters in each row. A 15×4 output configuration was used to end pump a Yb:S-FAP laser. A nearly on-axis multipass pumping system was developed to demonstrate how the asymmetry of the beam-shaped pump source can be exploited.

Laser diode pumped Cr 4+:YAG passively Q-switched Nd 3+:S-FAP laser

A laser diode pumped Cr 4+:YAG repetitively and passively Q-switched Nd 3+:S-FAP laser is studied theoretically and experimentally. The pulse energies, pulsewidths and pulse repetition rates in different conditions are measured and the experimental results are in agreement with the theoretical predictions on the whole.

Diode-pumped Q-switched Yb:S-FAP laser

A diode-pumped, repetitively Q-switched 1% doped Yb 3+:Sr 5(PO 4) 3F laser has been demonstrated for the first time, pumped with a strained InGaAs continuous-wave diode laser. The maximum output energy per pulse was 125 μJ at 1.047 μm, with a pulse duration of sub-30 ns. The Q-switched average power was identical to the steady-state CW power at repetition rates over 1 to 10 kHz, consistent with a 1.26 ms emission lifetime.

Diode-laser-pumped 1328-µm Nd:Sr_5(PO_4)_3F laser and its intracavity frequency doubling

Nd:Sr(5) (PO(4))(3) F, known as Nd:S-FAP, is a new material for efficient, miniature diode-pumped solid-state lasers. By using a laser-diode pump operating at 805.4 nm, we successfully lased Nd:S-FAP at 1.328 mum. A slope efficiency of 33.5% and a laser threshold of 18.5 mW have been measured. By using KTP as an intracavity doubling crystal, we also achieved an intracavity frequency Nd:S-FAP laser at 0.664 mum with a threshold power of 18.2 mW, a TEM(00) mode red laser output power of 20.7 mW at 250 mW incident pump power corresponding to an optical efficiency of 8.3%. In addition, we discuss ways to improve efficiency by use of this material.

Continuous-wave diode-pumped Yb 3+:S-FAP laser

A continuous-wave InGaAs diode-pumped Yb 3+:S-FAP laser has been demonstrated. We report an output power of 75 mW with a slope efficiency of 78%. Power improvements of up to 2.5 times are reported with crystal cooling.

Laser characteristics of a new crystal Nd:Sr 5(PO 4) 3F at 1.059 μm

The absorption spectrum of a new crystal Nd : Sr 5(PO 4) 3F or Nd : S-FAP, was measured, its two strong absorption peaks and broad effective absorption band showed that Nd : S-FAP can be appropriately pumped at 575 nm and 805.4 nm as well as with a xenon flashlamp. By using a tunable dye-laser (570.0~600.0 nm), a laser-diode (805 nm) and a xenon flash lamp as pump sources, respectively, the performance of a low threshold and high efficiency Nd:S-FAP laser at 1.059 (μm) (including pulse run, cw run, free-run and Q-switch run) has been demonstrated. The laser characteristics, such as the emission spectrum, the output energy, the output power, the pulse width, etc, were measured. In addition, the prospect of a Nd:S-FAP crystal for low-threshold high-efficiency miniature lasers is discussed.

Laser and spectroscopic properties of Sr_5[PO_4]_3F:Yb

Sr5(PO4)3F (S-FAP) has been investigated as a new Yb-doped laser crystal belonging to the apatite structural family. The spectroscopy of the Yb3+ ion and the laser properties of the medium have been investigated. The maximum absorption cross section of Yb in S-FAP is 8.6 × 10−20 cm2, and the maximum emission cross section is 7.3 × 10−20 cm2. The measured emission lifetime of Yb3+ is 1.26 ms. An Yb:S-FAP laser has been demonstrated with a Ti:sapphire laser pump operating at 899 nm. The Yb:S-FAP laser was measured to have slope efficiencies as high as 71%. The spectroscopy and laser studies are reported, as well as certain thermal, mechanical, and optical properties.