Double-resonance Optical-pumping Spectroscopy Of Rubidium Atoms And Its Application

Doppler-free laser spectroscopy for the transitions between atomic excited states, not just plays an important role in the field of high-resolution spectroscopy, multi-photon laser cooling and trapping of atoms, but also has great significance for the research of practical second-order frequency standards. But it difficult to acquire a laser spectrum in the transition between atomic excited states due to the lower thermal equilibrium population in excited states. The optical-optical double-resonance (OODR) method as a sophisticated technique has been widely utilized to approach a spectrum for transitions between atomic excited states; it has been widely studied and used in many theoretical and experimental researchers. However, the signal-to-noise ratio (SNR) of OODR spectrum is inadequate in atomic system with large spontaneous emission rates, which hampers its development. The main idea of DROP, a novel optical pumping spectroscopic technique, is to monitor the population of the atomic ground state under the condition of two-photon and optical pumping instead of the excited state. Compared with the traditional OODR spectrum, double-resonance optical-pumping (DROP) spectrum has advantage in flat base line and high-resolution spectrum. This paper focuses on the following aspects for research.(1) In order to get the high-resolution spectra of excited states for 87Rb 5P3/2-4D3/2(4D5/2) transition, we investigated and comparable the spectra for 87Rb 5P3/2-4D3/2(4D5/2) transition by use of the DROP and OODR techniques.(2) The influence of polarization combination, the laser power, and the alignment of coupling and probe laser beams (co-propagating and counter-propagating configurations) on the properties of DROP spectrum was discussed. On this basis, high-SNR and narrow line-width DROP spectra of 87Rb 5P3/2-4D3/2(4D5/2) transition is achieved under a proper condition.(3) The frequency of a 1529nm external- cavity diode laser (ECDL) is locked to 5P3/2(F'=3)-4D3/2(F"= 3)hyperfine transition by modulation-free frequency. When using DROP technique of counter-propagating configuration which coupling and probe laser beams counter-propagate along the Rb vapor cell. The result of residual frequency jitter after being locked is～650kHz within 300 s. This result is clearly much better than that in case of frequency stabilization by using OODR and DROP techniques of co-propagating configuration. We explore to establish a frequency reference in the vicinity of 196THz which belong to C-band of Dense Wavelength Division Multiplexing (DWDM) systems of optical telecommunication, which is expected to calibrate the optical channels.(4) It's difficult to measure hyperfine splitting of excited states of rubidium atoms by using common spectroscopic technology due to it's hyperfine splitting are usually small. On the basis of obtaining a high SNR and narrow line-width DROP spectra, employing the integrated guided-wave phase-type electro-optic modulator (EOM) and the spectral analysis technique of optical cavity, the hyperfine splitting of 4D3/2 and 4D5/2 states are measured precisely.