2-DIMENSIONAL MODE SIZE TRANSFORMATION BY DELTA-N-CONTROLLED POLYMER WAVE-GUIDES

We report a new type of polymer waveguide for two-dimensional (2-D) mo de size transformation in which Delta n (refractive index difference b etween core and cladding) is properly controlled along the waveguide s uds while the core cross section is kept uniform, The beam diameter in the Delta n-controlled waveguide where the core diameter is 3.7 mu m and Delta n changes from 0.0027 to 0.0009 toward one end in the 5 mm-g radient Delta n region, is about twice as large as that in a normal wa veguide where Delta n is 0.0027, The optical loss accompanied by mode size transformation is calculated to be less than 2.5% based on beam p ropagation methods (BPM's).