A spectroscopic Judd–Ofelt investigation has been performed on Er3+ in the doubly doped phosphate glass:Er3+, Yb3+ in order to assess its potential as a laser system. The standard Judd–Ofelt model was applied to the room-temperature absorption intensities of Er3+(4f11) transitions to determine the intensity parameters: Ω2=6.28×10−20 cm2, Ω4=1.03×10−20 cm2, and Ω6=1.39×10−20 cm2 in the phosphate glass host. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) and branching ratios of the Er3+ transitions from the excited-state J manifolds to the lower-lying J′ manifolds. The radiative lifetimes of these excited states are determined from the radiative decay rates. The predicted decay rates and radiative lifetimes are compared to those of Er3+ transitions in other glass hosts. The quantum efficiency of the eye-safe laser transition I13/24→4I15/2 (1.54 μm) of Er3+ is approximately 80% in the phosphate glass host.
Spectroscopic and laser properties of three different Er3+−doped garnet systems are characterized by employing the Judd–Ofelt (JO) analysis. The three garnet hosts are Y3Al5O12 (YAG), Y3Sc2Ga3O12 (YSGG), and Gd3Ga5O12 (GGG). The JO model has been applied to the room temperature absorption intensities of Er3+ (4f11) transitions to establish the so-called JO intensity parameters: Ω2, Ω4, and Ω6 in the three garnet hosts. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) and branching ratios of the Er3+ transitions from the excited state J manifolds to the lower-lying J′ manifolds. The predicted decay rates and branching ratios of these Er3+ transitions in YAG, YSGG, and GGG hosts are compared. From the radiative decay rates, the radiative lifetimes of the Er3+ excited states are determined in the three garnets and are also compared. We also report the spectroscopic quality factors, Ω4/Ω6, obtained for the three garnets. The quantum efficiencies of the I413/2→I415/2 Er3+ transition in YAG, YSGG, and GGG are determined to be ∼79%, 82%, and 85%, respectively.
A method for optical triggering of a Q-switched Nd:YAG laser by direct bleaching of a Cr:YAG saturable absorber is described. This method involves the bleaching of a thin sheet of the saturable absorber from a direction orthogonal to the lasing axis using a single laser diode bar, where the Cr:YAG transmission increased from a non-bleached value of 47% to a bleached value of 63%. For steady state operation of a passively Q-switched laser (PRF=10 Hz), the pulse-to-pulse timing jitter showed approximately 12X reduction in standard deviation, from 241 nsec for free running operation to 20 nsec with optical triggering.
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