Measurement of frequency sweep nonlinearity using atomic absorption spectroscopy

Abstract

A low cost scheme to determine the frequency sweep nonlinearity using atomic saturated absorption spectroscopy is demonstrated. The frequency modulation rate is determined by directly measuring the interference fringe number and frequency gap between two atomic transition peaks of rubidium atom. Experimental results show that the frequency sweep nonlinearity is ∼7.68%, with the average frequency modulation rate of ~28.95 GHz/s, which is in good agreement with theoretical expectation. With this method, the absolute optical frequency and optical path difference between two laser beams are simultaneously measured. This novel technique can be used for applications such as optical frequency sweep nonlinearity correction and real-time frequency monitor.

Determination of atomic density and collisional broadening of an alkali vapor by resonant interferometry

“…The laser used is a diode laser with a diffraction grating external-cavity emitting around the Cs D 2 line (λ=852 nm) and is scanned by simultaneously changing the grating angle and the injection current. The frequency scanning obtained by this method is nonlinear [15,16] and this must be taken into account for constructing the frequency axis of the measured spectra. To monitor the laser frequency we use a pump-probe spectroscopy set-up [17] together with a 1 GHz free-spectral range Fabry-Pérot (FP) interferometer.…”