Low-threshold, transversely excited NdP5O14laser

We have measured the room-temperature lasing behavior of NdP5OI4(NdPP) transverselypumped at 058-wm wavelength by a CW dye laser in an excitation geometrysimulatingthat of an LED or laser diode. For acrystal 760 Nm long, the lowest transversethreshold was 4 mW. From thisthresholdandatheoreticalrelationshipbetween excitation efficiency andpump wavelength, we predict that a threshold of approximately 8.5 mW should be possible for excitation by an edge-emitting 0.8-wm wavelength LED. Usingthin NdP P samples with reflecting back surfaces for better excitation efficiency should lower this threshold by -60 percent, andgiveminimumoptical-to-optical con- version efficiencies of - 3.5 percent.