R. C. Ohlmann, K. B. Steinbruegge, and R. Mazelsky, "Spectroscopic and Laser Characteristics of Neodymium-doped Calcium Fluorophosphate," Appl. Opt. 7, 905-914 (1968)
Laser oscillations have been produced in large crystals of Nd3+-doped Ca5(PO4)3F (the mineral fluorapatite, whence the coined name FAP) at room temperature under both tungsten lamp and flash lamp excitation. The laser tests show that FAP:Nd crystals have four times greater gain per incident pump energy and over one and a half times greater differential (slope) energy efficiency than equal size YAG:Nd crystals. The fluorescence, excitation, and absorption spectra of FAP:Nd are partially polarized, as expected for Nd3+ substituting Ca ii sites of C1h symmetry. The fluorescence lifetime is 0.24 msec at 300°K. Laser oscillations occur at 1.0629 μ in π polarization (E‖c), which has 2.6 times the gain of σ polarization (E⊥c).
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From x-ray data. There are 1.91 × 1022 Ca ions per cm3.
J. A. Nelson (unpublished).
Ordinary ray (o) refers to E⊥c axis polarization; extraordinary ray refers to E‖c axis polarization.
C. Hager and J. Valentich Westinghouse Research Laboratories (unpublished). Hysteresis in the measurement prevented the detection of any anisotropy less than 5%.
D. H. Damon, R. Mazelsky, W. Kramer, and P. A. Piotrowski (unpublished), measured on FAP:Nd (2 at.%) crystals.
Δ
= (2/π) area/peak intensity, applicable to a Lorentzian line shape, was used to obtain the line width. The resolution was about 4 cm−1. s: satellite line not seen in all samples; e: probably electronic transition; ev: either electronic or vibronic; v: probably vibronic in origin.
Resolution limited.
All laser rods 6.4-mm diam × 38-mm long. FAP rods oriented with axis ⊥c direction.
Materials all have 2.1 × 1020 Nd ions/cm3; equivalent to 1.1 at. % Nd in FAP and 1.5 at. % Nd in YAG.
Measured threshold, not corrected for spectrum change of the lamp.
Using 35% reflectivity output mirror.
All FAP rods oriented so the c axis is perpendicular to the rod axis.
One resonator was 99.9% reflecting.
Initial threshold is reported first; the threshold in parentheses is obtained by extrapolation of the linear part output vs input curves to zero output.
From x-ray data. There are 1.91 × 1022 Ca ions per cm3.
J. A. Nelson (unpublished).
Ordinary ray (o) refers to E⊥c axis polarization; extraordinary ray refers to E‖c axis polarization.
C. Hager and J. Valentich Westinghouse Research Laboratories (unpublished). Hysteresis in the measurement prevented the detection of any anisotropy less than 5%.
D. H. Damon, R. Mazelsky, W. Kramer, and P. A. Piotrowski (unpublished), measured on FAP:Nd (2 at.%) crystals.
Δ
= (2/π) area/peak intensity, applicable to a Lorentzian line shape, was used to obtain the line width. The resolution was about 4 cm−1. s: satellite line not seen in all samples; e: probably electronic transition; ev: either electronic or vibronic; v: probably vibronic in origin.
Resolution limited.
All laser rods 6.4-mm diam × 38-mm long. FAP rods oriented with axis ⊥c direction.
Materials all have 2.1 × 1020 Nd ions/cm3; equivalent to 1.1 at. % Nd in FAP and 1.5 at. % Nd in YAG.
Measured threshold, not corrected for spectrum change of the lamp.
Using 35% reflectivity output mirror.
All FAP rods oriented so the c axis is perpendicular to the rod axis.
One resonator was 99.9% reflecting.
Initial threshold is reported first; the threshold in parentheses is obtained by extrapolation of the linear part output vs input curves to zero output.