View article

We present double resonance optical pumping (DROP) spectra for the 5 P 3∕ 2–4 D 3∕ 2 transition and the 5 P 3∕ 2–4 D 5∕ 2 transition of R 87 b and we use these spectra for frequency stabilization in the 1.5 μ m region. The spectra, compared to the conventional double resonance spectrum, show a good signal-to-noise ratio and a narrow spectral linewidth for laser frequency stabilization. The different intensities of the hyperfine states were attributed to the different rates of double resonance optical pumping into the other ground state. When we stabilized the frequency of a 1.5 μ m laser diode to the DROP spectrum, the best frequency stability was 1× 10− 11 after 100 s⁠.