Experimental studies of the D2 line of 87 Rb vapour at 1.5 Tesla

Abstract

An investigation into the temperature evolution of transmission and absorption coefficient spectra of Rubidium atoms in the hyperfine Paschen-Back regime was successfully undertaken for a continuous laser detuning of approximately 150 GHz. All experiments were undertaken using a 1 mm long cell of isotopically enhanced 87Rb. The magnet used had a peak field of 1.54 T. The forms of both the S0 and S1 Stokes Parameters showed excellent agreement with the theory from ElecSus at temperatures ranging from 56◦C to 160◦C, with the S0 parameter also agreeing in narrow-band spectra of up to 20 GHz.The absorption coefficient ratio of strong transitions, expected to be equal to 3.00, was measured to be within their uncertainty of this value when a possible temperature fluctuation of <1 K was taken into account. Both the strong and weak transitions were measured and compared to the theory from ElecSus, which was found to successfully predict the behaviour of 87Rb atoms in the hyperfine Paschen-Back regime. Areas of expansion and improvement of the ElecSus program were identified.The power evolution of the D2 line of Rubidium was also investigated for a narrow beam of w < 0.4 mm in both no external magnetic field and the hyperfine Paschen-Back regime. The inhomogeneous shape of the power evolution was found to not fit the data, while the χ2 analysis showed that the homogeneous shape was better. The Weak Probe regime was found to be reached at values of I/Isat up to 2 orders of magnitude higher than the 1e−3 found previously. This provides possibilities for applications such that the SNR can be increased when measuring transmission or absorption coefficients. It is unclear whether the use of a magnetic field significantly changes the intensity required to reach the Weak Probe regime. This should be investigated using a wider beam, with a different experimental cell.