Determination of the spectral width of a laser transition from the Lamb dip

An expression for the Lamb dip in the output power of a laser is derived making allowance for depolarizing collisions and resonance trapping of radiation. It is shown that the spectral width of a laser line is less than the value which is obtained ignoring these effects. A method is suggested for estimating the degree of resonance trapping and for finding the radiative width corresponding to a transition from an excited to the ground state.