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A previous paper [D. K. Sardar et al., J. Appl. Phys. 93(5), 2602 (2003)] has reported Judd–Ofelt (J–O) spectroscopic properties of Er3+ in garnets Y3Al5O12, Y3(Sc2Ga3)O12, and Gd3Ga5O12. In that paper, the possible magnetic-dipole contribution to the oscillator strength, which is non-zero for the 4I13/2 ↔ 4I15/2 (1.5 μm) transition of Er3+, has been erroneously omitted in their J–O calculation, resulting in incorrect results of relevant spectroscopic parameters. In this Comment, we point out the error, perform correct J–O analysis, and report correct results. [ABSTRACT FROM AUTHOR]

Refractive index of optical material of powder is measured not as easily as a bulk material. Here, the prism coupling technique in combination with the immersion method is proposed to measure the refractive index of an optical material of powder. First, the powder material to be measured was dispersed in α-bromonaphthalene (C10H7Br) liquid to form a suspension mixture. The refractive index of the mixture, together with that of pure C10H7Br, was then measured at the wavelengths of 632.8, 1311, and 1553 nm using a commercial prism coupler. From the measured index values of pure C10H7Br and powder-dispersed mixture, the refractive index of the powder material was obtained on the basis of the Maxwell-Garnett model. Microcrystal powder from a LiNbO3 single-crystal, which has the known refractive index values, has been exemplified to demonstrate the method. The results show that the method is feasible with an accuracy of ±0.05. [ABSTRACT FROM AUTHOR]

A number of Li-deficient MgO-doped LiNbO 3 (LN) crystals with different Li 2 O contents ranging from 43.4 mol. % to 44.5 mol. % were prepared by carrying out the Li-poor vapor transport equilibration treatment on 5 mol. % (in growth melt) MgO-doped LN crystals. Unclamped electro-optic (EO) coefficients γ 13 and γ 33 of these crystals were measured by Mach-Zehnder interferometry. The results show that γ 13 (γ 33 ) increases linearly by ∼14% (11%) as the Li 2 O content decreases from 44.5 mol. % of the as-grown state to 43.4 mol. % of the Li-deficient state. This feature is desired for the EO application of the Li-deficient MgO:LN crystal.