Lasing properties of neodymium-doped calcium-niobium-gallium and calcium-lithium-niobium-gallium garnets at wavelengths of 1.06 and 1.33 μm

Abstract

Recent experiments on atom loss in ultra-cold Fermi gases all show a maximum at a magnetic field below Feshbach resonance, where the s-wave scattering length is large (comparable to inter-particle distance) and positive. These experiments have been performed over a wide range of conditions, with temperatures and trap depths spanning three decades. Different groups have come up with different explanations, including the emergence of Stoner ferromagnetism. Here, we show that this maximum is a consequence of two major steps. The first is the establishment of a population of shallow dimers, which is the combined effect of dimer formation through three-body recombination, and the dissociation of shallow dimers back to atoms through collisions. The dissociation process will be temperature dependent and is affected by Pauli blocking at low temperatures. The second is the relaxation of shallow dimers into tightly bound dimers through atom-dimer and dimer-dimer collisions. In these collisions, a significant amount of energy is released. The reaction products leave the trap, leading to trap loss. We have constructed a simple set of rate equations describing these processes. Remarkably, even with only a few parameters, these equations reproduce the loss rate observed in all recent experiments, despite their widely different experimental conditions. Our studies show that the location of the maximum loss rate depends crucially on experimental parameters such as trap depth and temperature. These extrinsic characters show that this maximum is not a reliable probe of the nature of the underlying quantum states. The physics of our equations also explains some general trends found in current experiments.

Tri-wavelength laser generation based on neodymium doped disordered crystal waveguide

“…As a new disorder laser crystal, neodymium-doped calcium niobium gallium garnet (Nd:CNGG) have attracted a continuous attention owing to its excellent properties on fluorescence and thermal properties [1][2][3][4][5][6][7]. It provides significant inhomogeneous broadening of fluorescence in the absorption and emission spectra, which is similar to the Nd-doped glass.…”

QUASI-Three-Level Laser Emissions of Neodymium-Doped Disordered Crystal Waveguides

“…A MONG the family of neodymium-doped disordered laser materials, neodymium ion doped calcium niobium gallium garnet (Nd:Ca 3 (NbGa) 2−x Ga 3 O 12 or Nd:CNGG) is an attractive gain medium. Owing to the random distribution of the niobium and gallium ions, it has lower melting point of 1460°C, broader absorption band and larger emission bandwidth compared with ordered crystals, which makes it suitable for multi-wavelength and ultra-short laser [1]- [3]. Based on the Nd:CNGG bulks, laser emissions at the wavelength of ∼930 nm [4], 1.06 μm [5] and 1.33 μm [6] have been realized.…”

Spectroscopy and energy transfer characteristics of Nd3+in CNGG

“…A characteristics of Nd3 laser emission in these crystals is the lasing at various wavelengths and onset oftimes6' 16under pulsed lamp pump either in the 1 .06 pm or 1 .33 im ranges6' 9 with different thresholds depending on Nd3 content. A comparison of Nd3 laser emission in CNGG and CLNGG laser crystals revealed differences in the emission characteristics and several advantages of the latter, such as: higher damage threshold (twofold), lower divergence and thermal lens effect at high pumping7.…”