Richard Utano

Crystallography, spectroscopic analysis, and lasing properties of Nd 3+ :Ba 2 ZnGe 2 O 7

Nd3+:Ba2ZnGe2O7 (BZAG) is an attractive material to be pumped by laser diodes because its fluorescence lifetime is 305 μsec and it has a broad absorption centered at 806 nm. In addition, Nd3+:BZAG has a broad fluorescence spectrum and offers the potential for tunable laser output wavelengths centered at 1.05 and 1.34 μm. Time-resolved, site-selection spectroscopy measurements revealed ten different crystal-field sites for Nd3+ in BZAG, but strong energy transfer between nonequivalent ions at room temperature results in emission from only one major site. Diode-array side pumping of 5-mm-diameter rods produced optical slope efficiencies of 22.8%. Crystal structure, Judd–Ofelt analysis, and laser performance are discussed.

Continuously tunable, 6–14 μm silver-gallium selenide optical parametric oscillator pumped at 1.57 μm

An angle tuned silver gallium selenide (AgGaSe2) optical parametric oscillator (OPO), pumped by the fixed wavelength 1.57 μm output of a noncritically phase-matched KTiOPO4 OPO, yielded radiation continuously tunable from 6 to 14 μm. Energies of up to 1.2 mJ/pulse with bandwidths of ∼5 cm−1   (full width at half-maximum) were obtained using a 6.5×6.5×35.3  mm long, type I AgGaSe2 crystal.

Crystal growth, spectroscopy, and laser performance of Nd 3+ :KYF 4

Nd3+-doped KYF4 boules (5 cm long by 2 cm diameter) have been grown by the top-seeded solution method. The broad absorption spectra near 800 nm and the long (>500 μs) fluorescence lifetime of the 4F3/2 laser state in this host are attractive diode-pump features with advantages over Nd3+:Y3Al5O12 and Nd3+:YLF4. We have investigated cw and Q-switched operation of Nd3+:KYF4 end pumped by a Ti: sapphire laser. Absorbed power slope efficiencies of 30% have been measured, but thermal effects limit input powers to 300 mW into the crystal.

Diode array side-pumped neodymium-doped gadolinium scandium gallium garnet rod and slab lasers

Gadolinium scandium gallium garnet (GSGG) was studied as a high average power laser host material utilizing diode array side pumping. Maximum optical slope efficiencies of 41.5% for Nd:GSGG in the rod geometry and 32.5% for a Nd:Cr:GSGG zig‐zag slab were obtained at 1.06 μm. Nd:GSGG and Nd:YAG have similar fluorescence lifetimes while Nd:GSGG has better energy storage capabilities due to its smaller stimulated‐emission cross section.

Improved longevities and novel wavelength generation from a solid state dye laser

Pyrromethene-BF2 (PM) complexes doped in modified polymethyl methacrylate were evaluated and show excellent laser efficiency and damage resistance when excited at 532 nm. The spectroscopy and laser performance of a new laser dye (PM511) is discussed with emission below 550 nm. In addition, the enhanced sensitization and dual wavelength operation of dyes doped in the solid-state are demonstrated between 550 - 650 nm.

8 - 12 µm generation using difference frequency generation in AgGaSe2 of a Nd: YAG pumped KTP OPO

An 1.06 μm pumped KTP optical parametric oscillator generates 8 to 12 μm by difference frequency mixing in AgGaSe2. Over 1 mJ at 8.2 μm is obtained.

Diode-array side-pumped Nd:YLiF 4 laser

A 6.3 mm diameter by 15 mm long a-axis Nd:YLiF4 (YLF) laser rod was side-pumped by a 475 W GaAlAs diode array. A 42.9 percent optical slope efficiency was achieved while pumping in a region of low absorption in the 2H9/2, 4F5/2 band at 806 nm. Findlay-clay loss analysis and pump absorption profiles are discussed.

OPO performance in the 6 - 14 µm band from 1.57 µm pumped AgGaSe2

The 1.57 μm signal output from a NCPM KTP OPO with gradient reflectivity mirror was used to pump a AgGaSe2 OPO. Continuous idler wavelength tuning was demonstrated from 6 to 14 μm, with energies up to 1 mJ/pulse and with a bandwidth of ~ 5 cm−1 FWHM.

7 - 12 µm generation using a Cr,Er:YSGG pump laser and CdSe and ZnGeP2 OPOs

2.79 μm Cr,Er:YSGG pumping of a CdSe OPO yielded a 59% slope efficiency (η) and 1.2–2.4 mJ of total idler output between 8.5 and 12.3 μm. A ZnGeP2 OPO operated with a lower threshold, η = 29%, and 0.7–2.4 mJ of forward idler output from 6.9 to 9.9 μm.