Spectroscopy with modulation sidebands

James K. Freericks, Andreas Dirks, Hulikal Krishnamurthy +1 more

David A. Holm, Murray Sargent

Treating the weak-sideband fields quantum mechanically, we study the effects of quantum noise on amplitude-modulation and frequency-modulation spectroscopy of two-level media. Our analysis demonstrates that quantum noise affects not only the intensities of the modulation sidebands but also their relative phase, which leads in particular to a quantum limit for frequency-modulation spectroscopy.

Zichao Zhou, Rong Wei, Chunyan Shi +1 more

We observe the modulation transfer spectroscopy on the D2 line of 87Rb in a rubidium cell with acoustic-optic modulator in the deep modulation regime. In this regime, the sidebands of the pump beam are involved in the four-wave mixing processes, which increase the signal gradients and the peak-to-peak amplitudes of both the absorption and dispersion components.

Wolfgang Demtröder

C. Affolderbach, W. Kemp, Svenja A. Knappe +2 more

We have performed a series of experiments demonstrating the use of a vertical-cavity surface-emitting laser for nonlinear spectroscopy on the cesium D2 transition at 852 nm wavelength. Due to the high modulation efficiency of the VCSEL sufficiently strong modulation sidebands at 9.2 GHz frequency can be produced by direct modulation of the laser injection current. Using, the carrier and one of the modulation sidebands coherent population trapping (CPT) resonances in a buffered cesium vapor can be prepared with linewidths of only 60 Hz. For application of these narrow resonances to precision magnetometry we find a sensitivity of 10 pT in 0.3 s integration time. For the use of our setup as a frequency reference a relative stability of 1 • 10 − 11 / τ is predicted. In both applications of CPT resonances the use of VCSELs as light sources helps to build compact and reliable devices.

J. I. Steinfeld, Paul L. Houston