Laser frequency stabilization on 5P  →  5D transition by double resonance optical pumping and two-photon transition spectroscopy in rubidium

Abstract

We present a laser frequency locking scheme for the high excited transition of rubidium, which cannot be directly referenced by atomic absorption spectroscopy. Double resonance optical pumping spectroscopy and two-photon transition spectroscopy of a 5S → 5P → 5D transition are obtained in a room temperature vapor cell and employed as the reference sources. An Allan deviation of 1.71 × 10 −12 at an averaging time of 2048 s with a residual frequency fluctuation of ±0.2 MHz over 7000 s is obtained by two-photon transition spectroscopy. The case of double resonance optical pumping spectroscopy presents an Allan deviation of 4.86 × 10 −12 at an averaging time of 2048 s with a residual frequency fluctuation of ±0.4 MHz over 7000 s. One distinct advantage of two-photon transition spectroscopy method is demonstrated by the analysis of the fast Fourier transform of error signal. A narrower full width at half-maximum of two-photon transition spectroscopy and a higher zero crossing slope by using a frequency modulation method lead to a better frequency stabilization. This work provides a technical basis for the laser frequency stabilization based on atomic and molecular transition spectroscopy, and it also supplies a new frequency standard for optical telecommunication applications.

High resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency

“…Obviously, DROP loses this ability of high resolution due to the spectral complexity of pumping effect. [8,9,34,[36][37][38][39][40][41] This comparison indicates that the far frequency detuning method is a nice spectroscopic means to reveal the fine structure in spectrum. It is due to the fact that the spectral method of DROP usually concern extra optical pumping channel, which rapidly reduces the population of the excited states.…”