Self-Writing of Tapered Pillars in UV-Curable Resin for Spot-Size Conversion

A new approach for fabricating spot size converters (SSCs), using self-written tapered pillars, is reported.  The method uses a UV-curable resin and mask transfer technique in order to fabricate pillar structures. These structures are designed to couple from Si-wire waveguides to silica single mode fiber (SMF).The technique improvises upon classic single shot fabrication, previously reported using an aperture-limited self-written waveguide (SWW) approach. Design optimization of the SSC was inferred through using a beam propagation method (BPM). A prototype of 24 arrayed SSCs with a 250 µm pitched separation was successfully fabricated using a photomask. Measurement of the Near Field Pattern (NFP) and Far Field Pattern (FFP) verified that the arrayed SSCs share similar light propagation characteristics.