Homogenous Planar Waveguide Lenses in Integrated Optics

Jiang, Pisu (1992) Homogenous Planar Waveguide Lenses in Integrated Optics. PhD thesis, University of Glasgow.

Abstract

Waveguide lenses are a key element in integrated optical devices. Even though several types of waveguide lenses have been developed, they do not fully satisfy the requirements of their applications. Existing waveguide lenses were reviewed and it was pointed out that the homogenous refracting lens has advantages over other types of waveguide lenses. Resolution, field of curvature, signal-to-noise ratio, field of view and relative aperture are the main characteristics of lens performance. A comprehensive understanding of the homogenous lens performance was obtained by raytracing and Huygens-Fresnel analysis. Anisotropic aberration was studied and the lens performance in an anisotropic waveguide was analysed. Even though the multi-element lens design provided excellent optical performance, even on anisotropic waveguide, the boundary losses limited its application. The existing one-element lenses had curvature of the focal field and anisotropic aberration was not taken into consideration in the design. A new one-element lens design lens was proposed, which, taking anisotropic aberration into consideration, was free of field curvature and had an acceptable resolution. Mode matching between two disparate waveguides was studied and it was shown that by careful design and choice of processing parameters mode mismatch would not significantly affect the coupling between two fundamental modes in high and low index waveguides. However, boundary scattering reduced the transmission of light power across the boundary and therefore the number of lens elements should be minimised. The fabrication of waveguide lenses was studied. Ti indiffused waveguide had advantages over dilute-proton-exchanged waveguide as a low index waveguide, but was subject to the risk of producing a spurious out-diffused waveguide. SiO2 gave the best behaviour in blocking proton exchange and was easy to process. Waveguide optical components, prisms and one-element lenses, were successfully fabricated, while the experimental four-element lens suffered low light power transmission due to boundary losses. In addition to the study of waveguide lenses, some other integrated optical devices were developed. Ti indiffused waveguide was buried by a subsequent proton exchange and annealing. The buried waveguide had low scattering loss, nearly symmetric optical intensity profile and single polarisation. The co-doping of Er and Ti enhanced the indiffusion rate of Er and much less annealing time was used than required in Er-only-doping.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Electrical engineering, Optics, Applied physics
• Date of Award: 1992
• Depositing User: Enlighten Team
• Unique ID: glathesis:1992-78406
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jan 2020 15:28
• Last Modified: 30 Jan 2020 15:28
• URI: https://theses.gla.ac.uk/id/eprint/78406