Method of fabricating fused and tapered couplers from optical fibers having photosensitive cladding regions

A fused/taper fiber optic coupler comprising:

• first and second optical fibers, each of the first and second optical fibers including a core section, an inner cladding layer coaxially disposed around the core section, and an outer cladding layer coaxially disposed around the inner cladding layer;
• the core section having a first index of refraction;
• the inner photosensitive cladding layer having a second index of refraction less than the first index of refraction and the outer cladding having an index of refraction substantially equal to the second index of refraction;
• first and second coupling regions in the first and second optical fibers respectively, within which the outer cladding layer has been circumferentially removed from the first and second optical fibers respectively, the first and second coupling regions having substantially the same length;
• a tapered coupling junction formed from the first and second coupling regions, wherein the first and second coupling regions are maintained substantially parallel and proximal to one another for optical coupling therebetween;
• a fiber Bragg grating disposed within the tapered coupling junction.