Modulation transfer spectroscopy (MTS) is widely used in an optical laboratory for laser frequency stabilization. There have been many theoretical and experimental papers on this spectroscopic method. However, most of the works focus on the cycling transitions like the D2 line of rubidium. In this paper, the MTS for noncycling transitions is investigated. We consider the D1 line of rubidium whose modulation transfer spectrum has been determined and compared to the polarization spectrum. It is found that the slope of the modulation transfer signal is sharper than the polarization spectrum. The performance of laser frequency locking based on the MTS method is better than that of the polarization spectroscopy method. The dependence of the signal amplitude on the temperature of the vapor cell was analyzed, and the high signal-to-noise-ratio spectra are achieved for D1 open transitions. The obtained results provide an effective spectroscopic method for the robust frequency locking of a laser at a wavelength of 795 nm.Modulation transfer spectroscopy (MTS) is widely used in an optical laboratory for laser frequency stabilization. There have been many theoretical and experimental papers on this spectroscopic method. However, most of the works focus on the cycling transitions like the D2 line of rubidium. In this paper, the MTS for noncycling transitions is investigated. We consider the D1 line of rubidium whose modulation transfer spectrum has been determined and compared to the polarization spectrum. It is found that the slope of the modulation transfer signal is sharper than the polarization spectrum. The performance of laser frequency locking based on the MTS method is better than that of the polarization spectroscopy method. The dependence of the signal amplitude on the temperature of the vapor cell was analyzed, and the high signal-to-noise-ratio spectra are achieved for D1 open transitions. The obtained results provide an effective spectroscopic method for the robust frequency locking of a laser at a wavelength of 795 nm.

Journal of the Optical Society of America BOct 8, 201830 citations

Spectroscopy with modulation sidebands

K. Takagi, Robert F. Curl, R. T. M. Su

Applied Physics AJul 1, 19759 citations

Optical pumping effect on modulation transfer spectroscopy of the D1 line of ⁸⁵Rb atoms with non-cycling transition

Jin‐Tae Kim, Shabraz Khan, Heung‐Ryoul Noh

The D_1 line of ^{85}Rb exhibits non-cycling transitions; therefore, only weak modulation transfer spectroscopy (MTS) signals could be obtained \cite{Khan2024}. In this study, however, strong MTS spectra were obtained for the D_1 line via optical pumping (OP) of the D_2 line of $^{85}$ Rb. Four linear parallel (lin \parallel lin) and linear perpendicular (lin\perplin), \sigma^+ - \sigma^+, and \sigma^+ - \sigma^- polarization configurations were investigated using an OP laser with four different polarizations such as linear horizontal (P), linear vertical (S), \sigma^+, and \sigma^- polarizations. Under the linear perpendicular configuration, the MTS signal for the F_g=3 \rightarrow F_e=2 transition of the D_1 line exhibited approximately a 41-fold increase in the signal slope in the presence of a linearly-polarized OP beam, compared with the signal slope obtained without OP. The calculated MTS spectra for the \sigma^+ \sigma^- configuration in the presence of \sigma^+- or \sigma^--polarized OP beam as an example matched well with experimental observations.The D_1 line of ^{85}Rb exhibits non-cycling transitions; therefore, only weak modulation transfer spectroscopy (MTS) signals could be obtained \cite{Khan2024}. In this study, however, strong MTS spectra were obtained for the D_1 line via optical pumping (OP) of the D_2 line of $^{85}$Rb. Four linear parallel (lin \parallel lin) and linear perpendicular (lin\perplin), \sigma^+ - \sigma^+, and \sigma^+ - \sigma^- polarization configurations were investigated using an OP laser with four different polarizations such as linear horizontal (P), linear vertical (S), \sigma^+, and \sigma^- polarizations. Under the linear perpendicular configuration, the MTS signal for the F_g=3 \rightarrow F_e=2 transition of the D_1 line exhibited approximately a 41-fold increase in the signal slope in the presence of a linearly-polarized OP beam, compared with the signal slope obtained without OP. The calculated MTS spectra for the \sigma^+ \sigma^- configuration in the presence of \sigma^+- or \sigma^--polarized OP beam as an example matched well with experimental observations.

Oct 3, 20250 citations

^{85}

Rb. Four linear parallel (lin \parallel lin) and linear perpendicular (lin\perplin), \sigma^+ - \sigma^+, and \sigma^+ - \sigma^- polarization configurations were investigated using an OP laser with four different polarizations such as linear horizontal (P), linear vertical (S), \sigma^+, and \sigma^- polarizations. Under the linear perpendicular configuration, the MTS signal for the F_g=3 \rightarrow F_e=2 transition of the D_1 line exhibited approximately a 41-fold increase in the signal slope in the presence of a linearly-polarized OP beam, compared with the signal slope obtained without OP. The calculated MTS spectra for the \sigma^+ \sigma^- configuration in the presence of \sigma^+- or \sigma^--polarized OP beam as an example matched well with experimental observations.