ARTIFICIAL SPECTRAL BROADENING OF LASERS WITH RANDOM TELEGRAPH NOISE

Three methods are given for imposing random telegraph phase or frequency noise on a stabilized cw laser thus giving explicit control of the coherence of the laser field. In the case of phase noise, the resulting laser spectrum consists of a carrier part with nearly Lorentzian shaped noise sidebands which have full-width at half maximum up to 14 MHz. Complete suppression of the carrier is possible if the phase is made to jump by ir radians. Frequency telegraph noise results in a laser power spectrum that can be single or double peaked, depending on the relative sizes of the average dwell time and the frequency jump. The laser field has been produced for studies of noise in nonlinear spectroscopic interactions. Measurements of the resulting laser spectra are presented. As an example of the application of such a noisy laser, some results from studies of the dependence of two photon absorption on higher-order optical coherences are given.