Abstract: A narrow-band diode pumped alkali laser (DPAL) comprising a diode emitter assembly of broad area diode lasers arranged in a stack or array to emit longitudinally at a power level in a power range of 10-1500 W through a frequency selective element assembly aligned and positioned in an external laser cavity to the diode emitter assembly. The frequency selective element assembly comprising: an optical cell containing alkali vapor positioned between a pair of crossed polarizers; a partially reflective mirror that reflects a portion of light passing through the optical cell back toward the diode emitter assembly; and magnetic field producing components that produce a magnetic field through the optical cell that creates a 90° polarization of light passing through the optical cell at a narrow-band frequency corresponding to the absorption line of alkali atom, attenuating components of the light passing through the optical cell at frequencies outside of the narrow-band frequency.

Abstract: An optically pumped, flowing gas, alkali metal laser includes a gas passageway transporting an alkali metal vapor and a hydrocarbon buffer gas, and a laser propagation passageway intersects the gas passageway and forms a main cell at the intersection. A pump laser is directed into the main cell and produces a main laser beam in the laser propagation passageway. The flowing hydrocarbon buffer gas is disposed in the main cell with a density to induce spin-orbit relaxation in the alkali metal vapor. At least one window is disposed in the laser propagation passageway, and the window is protected from deposits of alkali metal or carbon by a heated leading edge in the laser propagation passageway that re-vaporizes alkali metal and returns it to the gas passageway via a convective gas flow. The window is further protected by a cold block that liquefies alkali metal and by a colder block that solidifies alkali metal in the laser propagation passageway.