High-resolution spectroscopy of the 39K transitions at 770 nm and 13C2H2 saturated lines by a solid-state laser at 1.54 μm: toward an optical frequency standard in the optical communication band

A novel and compact Er-Yb:glass laser was developed and frequency doubled at 770.1 nm; the second harmonic beam was used for high-resolution saturated spectroscopy of the ³⁹K 4S_1/2 -4P_1/2 line. A second harmonic power in excess of 15 μW, with a conversion efficiency of ~220% W^-1, was achieved in a periodically poled lithium niobate waveguide. This 770 nm radiation will be used to build an optical frequency standard based on the potassium transition. In addition, saturation spectroscopy of ¹³C₂H₂ in a low-pressure gas cell inside a Fabry-Perot showed an absorption dip with 1.2 MHz linewidth