The present invention is a fused/taper fiber optic coupler and related methodologies for a fuse/taper fiber optic coupler with an FBG (508) that does not excite cladding modes and maintains the coupling regions of the fibers (100, 503, 504) in the proper relationship to one another without a complex and expensive process. As will be explained in greater detail below disclosed aspects of the fused/taper fiber optic coupler include the use of optical fibers (100, 503, 504) with a three layer structure. The optical fibers include a photosensitive core layer (106), a photosensitive inner cladding layer (104), and a photo-insensitive outer cladding layer (102). Coupling regions (506, 202) are formed in each optical fiber (100, 503, 504) by removing the outer cladding layer (102) and the coupling regions in each optical fiber (100, 503, 504) are then helically intertwined. The intertwined coupling regions are then heated and drawn forming a tapered area in which an FBG may be written.