LASER MODE COUPLING PRODUCED BY SUBMULTIPLE AXIAL MODE INTERVAL MODULATION OF THE OPTICAL CAVITY LENGTH

The report presents an analysis of laser mode coupling produced by moving one of the cavity reflectors at a frequency less than the quiescent axial mode interval. It is found that mode coupling results when the modulation frequency is a submultiple of the quiescent axial mode interval. Mode coupling by cavity-length modulation in lieu of phase or loss modulation eliminates the necessity of inserting elements within the laser cavity. Mode coupling by means of mirror motion is particularly advantageous at optical frequencies where low-loss electro-optic or acoustic diffraction materials are unavailable. Mode coupling at submultiples of the quiescent axial mode interval would be more physically realizable than c/2L mode locking because of the greater mirror excursions allowable. (Author)