Neodymium ground state depleted laser characterization and demonstration

A recently proposed class of rare earth doped solid state lasers is described. These ground state depleted (GSD) lasers are characterized by a low laser ion doping density (5--10 x 1018 ions/cc) and a large fractional excited population inversion density (4--8 x 1018 ions/cc). For efficiency, these lasers must be pumped by narrow-band (10--50 kW/cm2) sources. Four level operation at room temperature is obtained and efficient lasing to the ground electronic state manifold is achieved. The design domain of GSD lasers is dominated by the pump transition cross section (2--10 x 10- 20 cm2) and the associated saturation fluence/flux (2--10 J/cm2 and 10--50 kW/cm2). The GSD laser gain element is typically optically thick (Lambert law) at the pump wavelength, but is substantially bleached at the working pump intensity