VERY LOW-LOSS PASSIVE FIBER-TO-CHIP COUPLING WITH TAPERED FIBERS

A novel passive fiber-to-chip coupling based on the use of fiber taper s embedded in a guiding structure is proposed. By beam-propagation cal culations it is verified that this new coupling method exhibits a very low insertion loss. Major advantages of the proposed method compared with butt coupling are demonstrated by simulation results: first, tole rance requirements for the fibers, e.g., diameter variations and core eccentricity, and for fabrication of the alignment structure are reduc ed by at least 1 order of magnitude. Second, coupling to waveguides of nearly arbitrary dimensions and refractive indices seems to be possib le. Experimental results on thermal drawing of fiber tapers are presen ted and used as input data for the simulations. A concept for fabricat ion of the new coupling method with the Lithographic Galvanik Abformun g (LIGA) technique is presented. (C) 1997 Optical Society of America.