Alternative Methods for Creating a Sodium Guidestar

The objective of the proposed research is to demonstrate high-power, scalable, and stable laser sources at specific wavelengths with narrow linewidth matched to the single velocity class of mesospheric atomic sodium for guide star application. The operation at tailored wavelengths, 1141 nm and 1178 nm (for 589 nm via frequency doubling) is addressed by the use of bandgap-engineered optically pumped semiconductor lasers, which are capable of producing multiple watts to multiple tens of watts per single device in diffraction-limited transverse mode. The scalable architecture is realized by employing multiple VECSEL devices in one resonator, thus allowing high saturated output power of the laser device. With multiple resonant periodic gain (RPG) structures in one laser resonator, an issue arises concerning the stability of the standing wave pattern. We will solve this issue by using the twisted-mode configuration so that the antinode of the standing wave pattern always matches the location of the quantum wells, which provide optical gain.