Subpicosecond and continuous-wave laser operation of (F 2 + )H and (F 2 + )AH color-center lasers in the 2-μm range

We report synchronously mode-locked subpicosecond and continuous-wave color-center laser operation in the 1.8–2.4-μm wavelength range. For active materials we use (F2+)H centers in KBr:O2− and (F2+)AH centers in KBr:Na+:O2− crystals. When the lasers are pumped with a continuous-wave or mode-locked NaCl (F2+)H-center laser in a cascaded configuration, laser operation is obtained over the combined tuning range of 1.8–2.4 μm, with output powers as high as 150 mW. When synchronously mode locked with ~5-ps pump pulses, both KBr lasers yield typically ~1-ps pulse widths over the entire tuning range. Pulses as short as ~400 fs could be obtained at the expense of higher noise levels.