We achieve a compact ultra-stable 420 nm blue diode laser system by immediately stabilizing the laser on the hyperfine transition line of Rb atom. The Allan deviation of the residual error signal reaches 1 Hz-level Allan deviation within 1 s averaging time, and the fractional frequency Allan deviation is 1.4 × 10 −15 ∕ √ , which shows the best result of frequencystabilized lasers based on the atomic spectroscopy without Pound-Drever-Hall (PDH) system. The signal-to-noise ratio of the atomic spectroscopy is evaluated to be 3,000,000 from the Allan deviation formula, which is the highest record, to the best of our knowledge. The frequency noise suppression characterization is demonstrated and the maximal noise suppression can be near 40 dB at 6 Hz. As a good candidate of pumping source, the ultra-stable 420 nm diode laser is successfully used in our Rb four-level active optical frequency standard system. The method can be easily extended to other wavelengths ultra-stable lasers with a Allan deviation of 10 −15 level retaining an atomic reference with low cost and low complexity while in the absence of an expensive and complicated PDH system.

Nonlinear spectroscopy has become a useful tool in laser cooling, frequency stabilization and so on. We use the 455.5 nm light beam output of an external cavity diode laser to perform the saturation spectroscopy signal and polarization spectroscopy signal on the 6𝑆 1/2 → 7𝑃 3/2 transition in cesium. The measured linewidth of the 𝐹 4 → 4, 5 transition is as narrow as 1.40 MHz and that of the 𝐹 3 → 2, 3 transition is 1.67 MHz. Both of them are very close to the natural linewidth of about 1.2 MHz. Our result is the narrowest measured linewidth of Cs 455 nm saturation spectroscopy signal to our knowledge.

The intensity of fluorescence spectral lines of Rb atoms in the region of 350-1110 nm is measured in eletrodeless discharge lamp. The population ratio between the excited states is calculated according to the spontaneous transition probabilities with rate equations. At the same time, the population density of energy level is also obtained. The results provide the potential applications of electrodeless discharge lamp in atomic filter and optical frequency reference at higher excited states without a pumping laser. electrodeless discharge lamp, population ratio, population densityCitation:

We realize an experimental facility for cooling and trapping strontium (Sr) atoms and measure the Landé g factor of 3D1 of 88Sr. Thanks to a novel repumping scheme with the 3P2 → 3S1 and 3P0 → 3D1 combination and the permanent magnets based self-assembled Zeeman slower, the peak atom number in the continuously repumped blue magneto-optical trap is enhanced by a factor of 15 with respect to the non-repumping case, and reaches ∼1 billion. Furthermore, using the resolved-sideband Zeeman spectroscopy, the Landé g factor of 3D1 is measured to be 0.4995(88) showing a good agreement with the theoretical value of 0.4988. The results will have an impact on various applications including atom laser, dipolar interactions, quantum information and precision measurements.

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