A 420nm Blue Diode Laser for the Potential Rubidium Optical Frequency Standard

We report a 420 nm external cavity diode laser with an interference filter (IF) of 0.5 nm narrow-bandwidth and 79% high transmission, which is first used for Rb optical frequency standard. The IF and the cat-eye reflector are used for selecting wavelength and light feedback, respectively. The measured laser linewidth is 24 kHz when the diode laser is free running. Using this narrow-linewidth IF blue diode laser, we realize a compact Rb optical frequency standard without a complicated PDH system. The preliminary stability of the Rb optical frequency standard is 2\times10^-13 at 1 s and decreases to 1.9\times10^-14 at 1000 s. The narrow-linewidth characteristic makes the IF blue diode laser a well suited candidate for the compact Rb optical frequency standard.