Grating assisted coupler devices

The method of making a grating assisted coupler device from optical fibers comprising the steps of:

• providing a pair of single mode optical fibers having dopant distribution sufficient to photosensitize the cladding;
• prestretching one of the fibers 10-30%;
• stretching both fibers by heat and tension to form a fused waist region of less than about 10 microns in width in which the cores of the fibers are reduced to a dimension such that they do not affect light propagation;
• tensioning the waist region between spaced apart locations;
• in-diffusing a photosensitizing agent into the waist region while exposing the waist region to a light pattern forming a grating having a selected nominal wavelength response, and
• compensating for temperature induced variations in the wavelength response of the grating.

The method of making a polarization independent, high efficiency grating assisted optical wavelength coupler from optical fibers of initial cross-sectional shapes comprising the steps of:

• forming a longitudinally merged small coupling region from two optical fibers by elongating the fibers under tension and heating without twist;
• monitoring the polarization characteristics of the fibers during elongation;
• modifying the cross-sectional shapes of the fibers by varying the temperature and heating time during elongation until the desired polarization characteristics are achieved;
• tensioning the formed coupling region, and
• writing a grating in the coupling region.