Low-threshold semiconductor Raman laser

A semiconductor Raman laser using the longitudinal optical (LO) phonon mode of GaP has a very low threshold compared to the transverse optical (TO) phonon mode of GaP and even compared to simulated Raman scatterings in various kinds of liquids and insulating solid materials. The lowest threshold value of the pulsed input optical power is 8 kW (
5 \times 10^{6}
W/cm
²
) at room temperature. Far infrared radiation (24.8 μm) has been generated by placing both GaP with the LO phonon mode and GaAs with the TO phonon mode in a Fabry-Perot resonator. The maximum far infrared power has been 3 W.