Tunable frequency-stabilised laser for studying the cooling dynamics of Rb atoms in a magnetooptical trap

A system is developed which allows one to stabilise the diode laser frequency at any point in the vicinity of the cyclic D₂-line transition in Rb in the interval from +40 to -150 MHz and to switch the laser frequency within this interval for ~1 ms. A method is proposed and realised for increasing the contrast of the reference sub-Doppler resonance observed in circularly polarised fields. The ultimate contrast of the resonance is estimated. This system can be used to study the anomalous light pressure force acting on atoms in an optical molasses. A magnetooptical trap for Rb atoms is described.