An experimental investigation of two-color polarization spectroscopy (TCPS) is presented based on the cesium 6S_1/2 – 6P_3/2 – 8S_1/2 (852.3 nm + 794.6 nm) ladder-type system in a room-temperature vapor cell. The dependency of line shapes of TCPS on the power of a 852.3 nm pump and a 794.6 nm probe laser is measured in detail, and we confirm that the linewidth of TCPS in a counter-propagating configuration between the pump and probe laser beams is obviously narrower than that of a co-propagating configuration, due to the atomic coherence effect. It is helpful for laser stabilization of the excited state transition using TCPS without frequency modulation.

Atomic Doppler broadening thermometry (DBT) is potentially an accurate and practical approach for thermodynamic temperature measurement. However, previous reported atomic DBT had a long acquisition time and had only been proved at the triple point of water, 0°C, for the purpose of determination of the Boltzmann constant. This research implemented the cesium atomic DBT for fast room temperature measurement. The Cs¹³³ D1 (6S^1/2 → 6p^1/2 transition) line was measured by direct laser absorption spectroscopy, and the quantity of thermal-induced linewidth broadening was precisely retrieved by the Voigt profile fitting algorithm. The preliminary results showed the proposed approach had a 4 min single-scan acquisition time and 0.2% reproducibility. It is expected that the atomic DBT could be used as an accurate, chip-scale, and calibration-free temperature sensor and standard.

We report the observation of ultralow-power absorption saturation in a tapered optical fiber (TOF) mounted in a hot cesium (Cs) vapor in a vacuum chamber. The small optical mode area of TOF produces a great influence on optical properties, allowing optical interactions with nanowatt-level power. The comparison of transmission characteristics for the TOF system and free-space vapor is investigated at different input power and atomic density. The unique performance of the Cs-TOF system makes it a promising candidate in resonant nonlinear optical applications with ultralow power.

We propose an optical weighing technique with a sensitivity down to a single atom through the coupling between a surface plasmon and a suspended graphene nanoribbon resonator. The mass is determined via the vibrational frequency shift on the probe absorption spectrum while the atom attaches to the nanoribbon surface. We provide methods to separate out the signals of the ultralow frequency vibrational modes from the strong Rayleigh background, first based on the quantum coupling with a pump-probe scheme. Owing to the spectral enhancement in the surface plasmon and the ultralight mass of the nanoribbon, this scheme results in a narrow linewidth (～GHz) and ultrahigh mass sensitivity (～30 yg). Benefitting from the low noises, our optical mass sensor can be achieved at room temperature and reach ultrahigh time resolution.

The intensities of fluorescence spectral lines of Ca atoms and Sr atoms in two different hollow cathode lamps (HCLs) are measured by element-balance-detection technology. In the wavelength range of 350–750 nm in the visible spectral region, using the individual strongest line (Ca 422.67 nm, Sr 460.73 nm) as the bench mark, the population ratios between the excited states of Ca atoms and Sr atoms are calculated by rate equations and the spontaneous transition probabilities. The HCLs with populations at excited states can be used to realize the frequency stabilization reference of the laser frequency standard.

Vector beams with spatially variant polarization have attracted much attention in recent years, with potential applications in both classical optics and quantum optics. In this work, we study a polarization selection of spatial intensity distribution by utilizing a hybridly polarized beam as a coupling beam and a circularly polarized beam as a probe beam in Rb87 atom vapor. We experimentally observe that the spatial intensity distribution of the probe beam after passing through atoms can be modulated by the hybridly polarized beam due to the optical pumping effect. Then, the information loaded in the probe beam can be designedly filtrated by an atomic system with a high extinction ratio. A detailed process of the optical pumping effect in our configurations and the corresponding absorption spectra are presented to interpret our experimental results, which can be used for the spatial optical information locally extracted based on an atomic system, which has potential applications in quantum communication and computation.

A 1470 nm+852 nm two-color (TC) cesium (Cs) magneto-optical trap (MOT) with a 6S1/2-6P3/2-7S1/2 ladder-type system is proposed and experimentally investigated. To the best of our knowledge, it is the first report about the 1470 nm+852 nm Cs TC-MOT. One of the three pairs of the 852 nm cooling and trapping beams (CTBs) in a conventional Cs MOT is replaced with a pair of the 1470 nm CTBs. Thus, the TC-MOT partially employs the optical radiation forces from photon scattering of the 6P3/2 (F′=5) 7S1/2 (F′′=4) excited-state transition (1470 nm). This TC-MOT can cool and trap Cs atoms on both the red- and blue-detuning sides of the two-photon resonance. This work may have applications in cooling and trapping of atoms using inconvenient wavelengths and background-free detection of cold and trapped Cs atoms.

We experimentally observe polarization spectroscopy (PS) of the S01-P31 transition of mercury atom gases at 253.7 nm. The PS signal can be observed in all six richly abundant isotopes and the PS signal of six transitions for laser cooling are all clear and of a dispersive line shape. The optimized pump power and probe power are found for the PS of Hg202. We find the linearly polarized component in the pump beam will distort the original PS signal due to the use of linear PS. Consequently, the purity of the pump beam is crucial to laser frequency stabilization by PS.

Pulsed collimated blue light at 420.3 nm is generated in hot Rb vapor by upconverting the 778.10 nm pumping beam through four wave mixing process. The energy conversion efficiency exceeds 1% when a 45 cm-long, 170°C heated Rb cell is used. The influence of cell temperature, wavelength, and energy of a pumping laser are fully examined. The efficiency of the photon conversion is found to be more sensitive to the blue detuning of the pump light and less sensitive to the red detuning of the pump light. This phenomenon can be explained by stimulated hyper-Raman scattering involved in the four-wave mixing process.