It is pointed out that atoms placed in the presence of a static magnetic field undergo shifts of their energy levels and changes in their transition probabilities. Even at quite low static magnetic field values, these effects are important and must be taken into account when considering optical pumping or absorption experiments with alkali atoms. Linear absorption experiments with /sup 85/Rb, /sup 87/Rb, and /sup 133/Cs are described, and optical frequency shifts are given for natural rubidium. It is confirmed that important changes in atomic energy levels and transition probabilities arise even at quite low magnetic fields for the n/sup 2/P states of alkali atoms.<>

This paper describes a novel technique that can be used to measure the frequency response of an optical phase modulator. An interesting feature of this technique is that it does not require the use of an interferometer for phase-to-amplitude conversion, thus alleviating stability and alignment problems. Instead, the electro-optically induced birefringence of the modulator and a simple polarizer are used to transform phase modulation into intensity modulation. The latter is detected with a high-speed photodiode and, for a sinusoidal modulating signal, the resulting output power spectrum is shown to be related to the actual phase modulation index by simple mathematical expressions involving Bessel functions. Using only a spectrum analyzer, the magnitude and the variations of the modulation index are measured over a broad frequency range.< >

A random PSK modulated signal generated with an optical waveguide phase modulator is used to obtain an error signal and lock the frequency of an AlGaAs semiconductor laser to the 87Rb D2 line. The measured error signal is similar to that obtained with sinusoidal phase modulation under the same conditions. The technique could be applied to longer wavelength lasers and other types of laser that cannot be directly modulated such as fibre lasers.