Tantalum Pentoxide Waveguides for Photonic Crystal Circuits
Tantalum Pentoxide Waveguides for Photonic Crystal Circuits
This thesis presents a study of Ta2O5 aimed at exploring its optical properties and demonstrating practical waveguide structures for the construction of Si-compatible densely integrated multifunctional optical waveguide devices.
A reliable fabrication process for Ta2O5 rib waveguides with a range of geometries was established and the correlation between the modal field distributions and the waveguide geometries was studied. The results provide useful guidelines for the design of monomode waveguides, particularly at a wavelength of 1550nm, and the structures established were used as effective test beds for a variety of device structures studied in this thesis. The UY photosensitivity of the material was investigated based on a Ta2O5 rib waveguide Mach-Zehnder interferometer structure. A significant UV induced index change of Δn=-2.1xl0-3 at a wavelength of 1550nm was observed in Ta2O5 films with no hydrogen loading, demonstrating significant potential advantages for inscribing microstructures and tuning photonic crystals. The optical third-order nonlinearity was examined in a Ta2O5 stripe waveguide using self-phase modulation. The large nonlinear refractive index obtained, n2~7.2 X 10-19 m2/W, demonstrates the potential of this material for all-optical switching devices. Hybrid integration of a Ta2O5 stripe waveguide with a self-assembled microsphere grating was demonstrated as an alternative route to microstructuring. In this study, the waveguide was used as a structure for physically trapping the microspheres and for the interrogation of the grating transmission spectrum. A transmission stop-band close to the Bragg wavelength was observed, demonstrating the feasibility of this potentially cheap method for realising wavelength-dependent devices. Finally, a process for incorporating photonic crystals within Ta2O5 rib waveguides was established. The transmission spectra provide evidence of band-gap behaviour, which show promise for future photonic crystal devices incorporating Ta2O5 rib waveguides. In particular, the challenge of fabricating perpendicular sidewalls for nano-sized holes has been overcome.
Ta2O5 is shown to have great potential as a high-index waveguide material for application in a variety of planar lightwave circuit elements. Routes to solve the remaining development problems identified in this thesis are proposed, so that Ta2O5 waveguides may be applied in practical devices.
University of Southampton
Tai, Chao-Yi
5a9a315c-4db0-4809-984f-857a4210ebde
2004
Tai, Chao-Yi
5a9a315c-4db0-4809-984f-857a4210ebde
Tai, Chao-Yi
(2004)
Tantalum Pentoxide Waveguides for Photonic Crystal Circuits.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis presents a study of Ta2O5 aimed at exploring its optical properties and demonstrating practical waveguide structures for the construction of Si-compatible densely integrated multifunctional optical waveguide devices.
A reliable fabrication process for Ta2O5 rib waveguides with a range of geometries was established and the correlation between the modal field distributions and the waveguide geometries was studied. The results provide useful guidelines for the design of monomode waveguides, particularly at a wavelength of 1550nm, and the structures established were used as effective test beds for a variety of device structures studied in this thesis. The UY photosensitivity of the material was investigated based on a Ta2O5 rib waveguide Mach-Zehnder interferometer structure. A significant UV induced index change of Δn=-2.1xl0-3 at a wavelength of 1550nm was observed in Ta2O5 films with no hydrogen loading, demonstrating significant potential advantages for inscribing microstructures and tuning photonic crystals. The optical third-order nonlinearity was examined in a Ta2O5 stripe waveguide using self-phase modulation. The large nonlinear refractive index obtained, n2~7.2 X 10-19 m2/W, demonstrates the potential of this material for all-optical switching devices. Hybrid integration of a Ta2O5 stripe waveguide with a self-assembled microsphere grating was demonstrated as an alternative route to microstructuring. In this study, the waveguide was used as a structure for physically trapping the microspheres and for the interrogation of the grating transmission spectrum. A transmission stop-band close to the Bragg wavelength was observed, demonstrating the feasibility of this potentially cheap method for realising wavelength-dependent devices. Finally, a process for incorporating photonic crystals within Ta2O5 rib waveguides was established. The transmission spectra provide evidence of band-gap behaviour, which show promise for future photonic crystal devices incorporating Ta2O5 rib waveguides. In particular, the challenge of fabricating perpendicular sidewalls for nano-sized holes has been overcome.
Ta2O5 is shown to have great potential as a high-index waveguide material for application in a variety of planar lightwave circuit elements. Routes to solve the remaining development problems identified in this thesis are proposed, so that Ta2O5 waveguides may be applied in practical devices.
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Published date: 2004
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Local EPrints ID: 465314
URI: http://eprints.soton.ac.uk/id/eprint/465314
PURE UUID: 2ec2ca30-7ed9-4797-b934-9d780fdd41fb
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Date deposited: 05 Jul 2022 00:37
Last modified: 16 Mar 2024 20:06
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Author:
Chao-Yi Tai
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