DIELECTRIC WAVEGUIDE LASERS HAVING A PASSIVE THIN-FILM CORE AND PERIODIC MIRROR SYSTEMS

摘要

ABSTRACT OF THE DISCLOSUREThe laser devices are energy-converting systems producinglight output when pumped and comprise multi-layer thin filmwaveguide structures consisting of:- a passive thin film dielectric core slab having longitud-inally-distributed periodic diffracting structural modula-tion along at least end portions of its length for effect-ing reversal of propagation direction of a bound mode ormodes;- a contiguous layer of active dielectric medium, i.e. asolid or fluid gain medium, the cladding thickness beingof the order of at least 100 microns, disposed on eitheror both major surfaces of the core slab;- an optically-flat solid substrate supporting the coreslab and maintaining the major surfaces thereof in precis-ely plane-parallel relation, which substrate may itself bean active gain medium.Incident pumping light, for example 3371 .ANG. wavelength coherentlight output from a nitrogen laser is caused to irradiate theactive medium, either penetrating its surface from the exterior,or the pumping light may be coupled into the thin film core bysuitable means such as prisms, gratings, etc. as a guided mode forevanescent-wave component interaction with the cladding layer.Monochromatic output lasers have a core thickness chosen so thatfor a given dielectric constant differential with respect to thecladding layers a single mode propagates, and the mode-reversingstructure is a first-order blazed reflection grating with blazeangle correlated to the boundary-reflection angle of the lasingmode for augmenting the proportion of reversed mode energy tozero-order diffracted energy. Plural-frequency output lasersemploy first or higher order diffracting structure, obtaining inter-mode energy reversal, and intra-mode energy reversal.