Vertically tapered epilayers for low-loss waveguide-fiber coupling achieved in a single epitaxial growth run

• Published in: Journal of lightwave technology Vol. 21; no. 1; pp. 211 - 217
• Main Authors: Balmer, R.S., Heaton, J.M., Maclean, J.O., Ayling, S.G., Newey, J.P., Houlton, M., Calcott, P.D.J., Wight, D.R., Martin, T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2003; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Circuit properties; Converters; Costs; Coupling circuits; Electric, optical and optoelectronic circuits; Electronics; Epitaxial growth; Exact sciences and technology; Integrated optics; Integrated optics. Optical fibers and wave guides; Joining; Microelectronic fabrication (materials and surfaces technology); Noise levels; Optical and optoelectronic circuits; Optical coupling; Optical devices; Optical fibers; Optical waveguides; Optoelectronic devices; Optoelectronics; Semiconductor device packaging; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductor waveguides; Semiconductors; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Waveguides; Passive component; Performance evaluation; Cost minimization; Optical telecommunication; shadow-masked growth; Electronic circuit; Shadow; Optical transmission; Electronic packaging; Optoelectronic device; Chemical beam epitaxy; Converter; Optical waveguide; Monolithic integrated circuit; Wafer; Optical fiber; Tapered waveguide; opto-electronic circuits; Low-loss waveguide-fiber coupler; Waveguide; Optical system; Electronic component; mode-size converter; Waveguide junction; Miniaturization
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2003.808672

Next-generation optical-communications systems require on-wafer integration of active and passive opto-electronic components to increase operating speed and reduce packaging costs. Increased coupling efficiencies between semiconductor waveguides and optical fibers are of particular interest. A simple and cost-effective method of fabricating a mode-size converter monolithically integrated with a semiconductor waveguide is presented. An on-wafer mode-size converter reduces the number of interfaces in an opto-electronic circuit and improves the coupling efficiency between semiconductor waveguide and optical fiber. Vertically tapered epilayers are deposited in a single epitaxial growth run using shadow-masked growth by chemical-beam epitaxy, avoiding complex and expensive processing and regrowth stages. Waveguides that taper vertically and horizontally over /spl sim/1 mm for gradual expansion of the mode size are demonstrated. Waveguide loss measurements showed that there was negligible loss across the tapered regions. A loss of <2 dB/interface was achieved compared with /spl sim/8 dB/interface for a butt-coupled discrete device.