Fabrication of asymmetric multimode splitters in glass by planar ion exchange and laser ablation

The fabrication of planar lightwave circuits (PLC) using the laser-ablated ridge waveguide technique is explored. In particular, asymmetric multimode splitter structures are designed and fabricated. The experimental work is accompanied by modeling the relevant parameters. An ion exchange model determines a suitable set of ion exchange duration, temperature, electric field, and ridge geometry. In the simulation, special attention is paid to a good match of the waveguide shape between the PLC components and commercially available GRIN fibers. Wave-optical simulations of the light propagation in the PLC devices are performed using a scalar beam propagation method. Based on the simulation, asymmetric splitter devices are designed for a variety of splitting ratios. A 70:30 splitter is fabricated and attached to optical fibers for characterization. As indicated by a low excess loss, low intrinsic waveguide losses are achieved. The experimental splitting ratio is in good agreement with the simulation