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Recent developments in Cr{sup 2+}-doped II-VI compound lasers

Description: Transition-metal-doped zinc chalcogenide crystals have recently been investigated as potential mid-IR lasers. Tetrahedrally-coordinated Cr{sup 2+} ions are especially attractive as lasants on account of high luminescence quantum yields for emission in the 2000-3000 nm range. {sup 5}E radiative lifetimes and emission cross sections are respectively {approximately}10 {mu}sec and {approximately}10{sup -18} cm{sup 2}. The associated absorption band peaked at {approximately}1800 nm enables laser-diode pumping of the Cr{sup 2+} systems. Laser demonstrations with ZnS:Cr and ZnSe:Cr (using a MgF{sub 2}:Co{sup 2+} laser pump source) gave slope efficiencies up to 30%. Excited-state-absorption losses appear small, and passive losses dominate. Tuning experiments with a birefringent filter evidence a tuning range covering at least 2280 - 2530 nm. Cr-doped laser samples can be produced by Bridgman growth, seeded physical vapor transport, or diffusion doping.
Date: September 1, 1996
Creator: Page, R.H.; DeLoach, L.D.; Schaffers, K.I., Patel, F.D.; Beach, R.J.; Payne, S.A.; Krupke, W.F. et al.
Partner: UNT Libraries Government Documents Department

Nd3+ and Yb3+ doped phosphate glass waveguides fabricated using electric field assisted Ag+ diffusion

Description: Solid-state waveguide lasers offer several attractive features that may make high efficiency and effective thermal management possible. Due to the ability to confine pump light to high intensity over distances much longer than the Rayleigh range, as well as maintaining good overlap between the pump and Iasing modes over the entire guiding region, effcient operation with high slope efficiency should be possible, even for quasi-three level laser systems. Since the waveguide region is typically only a few microns of thickness, heat can be extracted efficiently from the structure. The effects of heating are of less significance than in bulk solid-state lasers because mode confinement is maintained by an index of refraction difference, usually much larger than tnat induced by dn/dT or stress-optic effects. Rare earth doped waveguide laser action has been reported in numerous papers [14]. The processes for fabricating waveguides include film deposition methods such as epitaxial growth, RF sputtering, and most recently, thermal bonding of precision finished crystals [5]. In addition, ion implantation, ion exchange in a molten salt and electric field assisted solid film diffusion [6] have been utilized. The ion exchange method remains the simplest, particularly for many common laser glasses that already have mobile ions, and has received considerable attention in recent years. An excellent review is found in reference [7]. Our work has focused on developing process conditions for the fabrication of waveguides in phosphate laser glasses using solid silver film diffusion. These processes are important in determining the overall structure and properties of the guiding region, such as propagation loss, modal profile, and modal overlap between the pump and laser wavelengths. Phosphate laser glass was chosen as the solid state laser medium due to the useful spectroscopic properties of rare earth ions in these materials, as well as the range of material properties ...
Date: December 17, 1997
Creator: Patel, F.D.; Honea, E.C.; Krol, D.; Payne, S.A. & Hayden, J.S.
Partner: UNT Libraries Government Documents Department

A diode-pumped channel waveguide laser fabricated in Nd: phosphate glass

Description: We report on the laser performance of a Nd:phosphate glass (Nd:IOG-1) channel waveguide laser fabricated by electric field assisted Ag{sup +} diffusion. Lasing was achieved in two different size channels, 29 x 9 {micro}m{sup 2} and 50 x 9 {micro}m{sup 2}, on a sample of length 8 mm. Slope efficiencies of {approximately} 15% with respect to incident pump power were measured. Losses in the 29 um wide channel were measured to be in the range 0.2--1.1 dB/cm and in the 50 mm channel, 0.2--0.4 dB/cm. The laser spectrum, centered about the emission peak of 1053 nm, was multimode and randomly polarized.
Date: January 29, 1999
Creator: Patel, F D; Honea, E C; Krol, D; Payne, S A & Hayden, J
Partner: UNT Libraries Government Documents Department