Fabrication of optical inverted-rib waveguides using UV-imprinting

• Published in: Microelectronic engineering 2011-02, Vol.88 (2), p.175-178
• Main Authors: Wang, Meng, Hiltunen, Jussi, Uusitalo, Sanna, Puustinen, Jarkko, Lappalainen, Jyrki, Karioja, Pentti, Myllylä, Risto
• Format: Article
• Language: English
• Subjects: Applied sciences; Circuit properties; Cladding; Cross-disciplinary physics: materials science; rheology; Electric, optical and optoelectronic circuits; Electronics; Etching; Exact sciences and technology; Fabrication; Integrated optics. Optical fibers and wave guides; Inverted-rib waveguides; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Lithography; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microelectronic fabrication (materials and surfaces technology); Molds; Optical and optoelectronic circuits; Other materials; Photoresists; Physics; Polymer waveguides; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Slabs; Specific materials; Stability; Tuning; UV-imprint; Waveguides
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2010.10.007

In this paper we introduce a fabrication process for polymer rib waveguides that uses UV-imprint lithography. In the structure of an inverted-rib waveguide, the lower cladding of the waveguide is patterned by UV-imprinting and the waveguiding layer is subsequently spin-coated. That makes the thickness of the formed slab layer on the rib waveguide controllable by tuning the spin-coating parameters. The fabrication process utilizes two steps of UV-imprinting. The first one is to form a rigid polymer mold from positive tone photoresist. The second one is to pattern the waveguide lower cladding with the formed polymer mold. Through the two steps of UV-imprinting, rib waveguides can be fabricated without an etching procedure. We demonstrated the proposed fabrication process by fabricating 2-μm-wide waveguides operating in single mode at 1310 nm. With TE-polarized light, the fabricated waveguides show an average transmission of 58.6% in a 30 mm long waveguide, corresponding to a loss of 2.3 dB.