Quantum intensity fluctuations in multimode cw lasers and maximum sensitivity of intracavity laser spectroscopy

A model using rate equations which allow for quantum noise is used to make a theoretical analysis of the steady-state lasing regime of a cw dye laser. Equations describing the laser performance are derived in the adiabatic approximation neglecting spatial inhomogeneities in the burnup of the active medium. An investigation is made of the stability of steady-state multimode laser action and it is found that this is weak in certain modes. Calculations are made of correlation functions describing fluctuations in the numbers of photons in the modes and fluctuations in the total intensity. Although the fluctuations in individual modes are large, the integrated intensity fluctuates negligibly. An analysis is made of the influence of quantum intensity fluctuations on the attainment of maximum sensitivity in intracavity laser spectroscopy.