A new ~1 <i>μ</i> m laser crystal Nd:Gd ₂ SrAl ₂ O ₇ : growth, thermal, spectral and lasing properties

Abstract Nd:Gd 2 SrAl 2 O 7 crystals were grown by the Czochralski technique; thermal, spectral and laser properties were investigated in detail. The average thermal expansion coefficients along a - and c -axis are 12.6 × 10 −6 K −1 and 14.9 × 10 −6 K −1 , respectively. At room temperature, the thermal conductivities are 4.98 and 5.24 W (m −1 * K −1 ) along the a - and c -axis, respectively. The absorption cross sections at ~808 nm are 13.7 × 10 −20 cm 2 with a FWHM of 3.3 nm for π -polarization and 11.84 × 10 −20 cm 2 with a FWHM of 3.4 nm for σ -polarization. The emission cross sections at ~1080 nm are 15 × 10 −20 cm 2 and 12.7 × 10 −20 cm 2 with a FWHM of about 5.1 nm and 12.5 nm for π - and σ -polarization, respectively. The fluorescence lifetime for the 4 F 3/2 → 4 I 11/2 transition was fitted to be 118 µ s. Pumped by a fiber-coupled 808 nm laser diode, the maximum 1.55 W continuous-wave laser output at ~1.08 µ m was achieved with a slope efficiency of 30.5%. All the results show that Nd:Gd 2 SrAl 2 O 7 crystal is a promising laser material.

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