Near-infrared laser operation of Cr3+ centers in chromium-doped LiInGeO4 and LiScGeO4 crystals.

Laser action has been demonstrated in two new tunable Cr3+-doped crystals. Absorption, emission, and excitation measurements for various crystal orientations have been performed for chromium-doped LiInGeO4 and LiScGeO4 single crystals. From the spectroscopic measurements, two optical active centers were identified: tetrahedrally coordinated Cr4+ and octahedrally coordinated Cr3+. Gain-switched, tunable laser operation of Cr3+ centers has been demonstrated in both crystals. An ultrawide tuning range from 1150 to 1480 nm for LiInGeO4 and 1220-1380 nm for LiScGeO4 has been achieved. To our knowledge this is the widest bandwidth and the most near-infrared shifted wavelength range for lasing ever demonstrated for Cr3+ ions.