TUNABLE FREQUENCY-CONTROLLED LASER SOURCE IN THE NEAR-ULTRAVIOLET BASED ON DOUBLING OF A SEMICONDUCTOR DIODE-LASER

Continuously tunable ultraviolet laser radiation at 397 nm was generat ed by doubling the output of a semiconductor diode laser. The fundamen tal radiation was provided by a 150 mW AlGaAs laser diode injected by a low-power AlGaAs laser diode which was frequency stabilized by optic al feedback using a new scheme of a miniature external cavity. Second- harmonic generation was produced in a lithium-triborate crystal placed in a compact enhancement cavity. The fundamental radiation was used f or sub-Doppler spectroscopy of the Ar I 4s(3)P degrees(0)-4p(1)P(1) tr ansition at 795 nm; the second-harmonic radiation was used for spectro scopy of the Ca II 4(2)S(1/2)-4(2)P(1/2) transition at 397 nm.