Optical stimulated emission transitions in Rydberg matter observed in the range 800-14 000 nm

The stimulated emission signal from a tunable cavity with Rydberg matter as the lasing medium is studied. The Rydberg matter is excited by heating through a non-radiative process. The emission bands are resolved by diffraction up to the fifth order using several different gratings in the cavity. The signal variation with wavelength is strong, especially in the wavelength range < 2000 nm. The wavelength variation of the signal over the range 800-14 000 nm is compared with Rydberg matter theory giving good agreement. The transitions observed are from n'' = 40-80 down to 6-21. There are no bands in the visible range, which is explained from the possible excitation levels in Rydberg matter. Reflecting some light out of the cavity gives lower gain (higher loss) and sharper bands, demonstrating that the device is indeed a working laser