Atomic spectroscopy with violet laser diodes

Laser spectroscopy with laser diodes can now also be performed in the violet/blue spectral region. a 5 mW commercially available CW laser diode operating at 404 nm was used to perform spectroscopy on potassium atoms with signal detection in absorption as well as fluorescence when operating on a potassium vapor cell and with optogalvanic detection on a potassium hollow cathode lamp. The 4s(2)S(1/2)-5P(2)P(3/2,1/2) transitions were observed at 404.5 and 404.8 nm, respectively. The laser diode was operated with a standard laser diode driver, and with or without an external cavity. The 4s(2)S(1/2)-4p(2)P(1/2) transition at 770.1 nm was also observed with a different laser diode. Here, Doppler-free saturated-absorption signals were also observed, enabling the evaluation of the ground-state hyperfine splitting of about 460 MHz. The data recorded allows an experimental verification of the theory for Doppler broadening at two widely separated wavelengths. (C) 2000 American Association of Physics Teachers.