Off-resonance laser frequency stabilization using the Faraday effect

Abstract

We present a simple technique for stabilization of a laser frequency off resonance using the Faraday effect in a heated vapor cell with an applied magnetic field. In particular we demonstrate stabilization of a 780 nm laser detuned up to 14 GHz from the 85 Rb D 2 5 2 S 1/2 F = 2 to 5 2 P 3/2 F ′ = 3 transition. Control of the temperature of the vapor cell and the magnitude of the applied magnetic field allows locking ∼6-14 GHz red and blue detuned from the atomic line. We obtain an rms fluctuation of 7 MHz over one hour without stabilization of the cell temperature or magnetic field.

Stabilization of a laser on a large-detuned atomic-reference frequency by resonant interferometry

“…Notice that this is a frequency stability similar to that obtained in [10] where a variation of 200 MHz/…”

“…Specifically, using a 1mm-thick cell and atomic densities around 2 × 10 14 atoms/cm 3 , we were able to lock the laser frequency in a range (deviations of 4 MHz) for an integration time of 300 s. The main source of instability of the reference signal is fluctuation of the atomic density through modifications of the temperature of the Cs reservoir. We estimate a displacement rate due to fluctuations of the reservoir temperature of 0.05δ/ • C, similar to the technique reported in [10]. The higher Fractional Frequency deviation that we have obtained relative to [10] is attributed to two factors: i) to the fact that the electronic feedback circuit is slow (an integrator with time constant of tens of seconds scales) and ii) to drift of the locking point due to fluctuation of the reservoir temperature of the order of 3 Mhz in a time scale of 100s.…”

“…We estimate a displacement rate due to fluctuations of the reservoir temperature of 0.05δ/ • C, similar to the technique reported in [10]. The higher Fractional Frequency deviation that we have obtained relative to [10] is attributed to two factors: i) to the fact that the electronic feedback circuit is slow (an integrator with time constant of tens of seconds scales) and ii) to drift of the locking point due to fluctuation of the reservoir temperature of the order of 3 Mhz in a time scale of 100s. Our theoretical model indicates that the range of stabilization can be extended by using, for example, either higher atomic densities or thicker cells.…”

“…Marchant and co-authors [10] used a high magnetic field to induce a Faraday rotation in a laser beam that is transmitted through an atomic vapour. The imbalance of the transmitted power in two orthogonal polarization components is used as the reference signal.…”

Continuous Faraday measurement of spin precession without light shifts

“…As a spectroscopic tool, the effect has been exploited for ultranarrow optical filters [15,16], ultrasensitive spectroscopy [17], laser stabilization [18] and optical frequency standards [19]. Resonant Faraday probing * lincoln.turner@monash.edu of spins undergoing Larmor precession results in the polarization angle of transmitted light oscillating at the Larmor frequency.…”