{"id":{"repo_id":"soton","oai_identifier":"oai:eprints.soton.ac.uk:50699"},"canonical_url":"https://search.dev.ndltd.org/etd/soton/oai:eprints.soton.ac.uk:50699","repository":{"repo_id":"soton","name":"University of Southampton","base_url":"https://eprints.soton.ac.uk/cgi/oai2"},"display":{"title":"Direct UV writing of structures in lithium niobate and lithium tantalate","abstract":"This thesis presents results from fabrication of UV direct write structures in lithium niobate and lithium tantalate. Unassisted direct writing of surface channel waveguides using lambda = 244 nm cw light resulted in polarisation specific waveguides fabricated on z- cut crystals. Waveguides were characterised using mode profiles, propagation losses, numerical aperture and refractive index measurements. In z-cut congruent lithium niobate, waveguides were written on the +z and -z faces producing structures that guided TM polarisation only with +z face waveguides exhibiting the lowest propagation loss of ~ 2 dB/cm, a maximum refractive index difference of ~ 8 x 10<sup>-4</sup> and a mean lifetime tau of ~ 4.5 days. The waveguiding mechanism is believed to be due to a lithium out-diffusion enhanced by a transient photorefractive effect. Waveguides were also written in stoichiometric and doped samples to test improvements in waveguide lifetimes. Surface domain reversal was observed in congruent lithium niobate on both +z and -z faces. Channel waveguides written into lithium tantalate were characterised and compared with lithium niobate.<br/><br/>Surface ferroelectric domain reversal via illumination of single pulsed lambda = 266 nm light through a phasemask on +z face congruent lithium niobate produced ordered alignment of domain lines along the crystallographic y-axes with minimum domain separation width of ~ 2 μm. Results from high temperature exposures and multipulse regimes are presented and a domain formation mechanism is proposed via an Nb anti-site model.","abstract_html":"This thesis presents results from fabrication of UV direct write structures in lithium niobate and lithium tantalate. Unassisted direct writing of surface channel waveguides using lambda = 244 nm cw light resulted in polarisation specific waveguides fabricated on z- cut crystals. Waveguides were characterised using mode profiles, propagation losses, numerical aperture and refractive index measurements. In z-cut congruent lithium niobate, waveguides were written on the +z and -z faces producing structures that guided TM polarisation only with +z face waveguides exhibiting the lowest propagation loss of ~ 2 dB/cm, a maximum refractive index difference of ~ 8 x 10&lt;sup&gt;-4&lt;/sup&gt; and a mean lifetime tau of ~ 4.5 days. The waveguiding mechanism is believed to be due to a lithium out-diffusion enhanced by a transient photorefractive effect. Waveguides were also written in stoichiometric and doped samples to test improvements in waveguide lifetimes. Surface domain reversal was observed in congruent lithium niobate on both +z and -z faces. Channel waveguides written into lithium tantalate were characterised and compared with lithium niobate.&lt;br/&gt;&lt;br/&gt;Surface ferroelectric domain reversal via illumination of single pulsed lambda = 266 nm light through a phasemask on +z face congruent lithium niobate produced ordered alignment of domain lines along the crystallographic y-axes with minimum domain separation width of ~ 2 μm. Results from high temperature exposures and multipulse regimes are presented and a domain formation mechanism is proposed via an Nb anti-site model.","abstract_has_math":false,"creators":["Wellington, Iain"],"institution":"University of Southampton","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Eason, R.W."],"committee_chairs":[],"committee_members":[],"year":2007,"date_issued":"2007-10","date_published":"2007-10","updated_at":"2026-07-24T04:35:50Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Eason, R.W."]},{"key":"dc:creator","label":"Author","values":["Wellington, Iain"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2007-10"]},{"key":"dc:date.issued","label":"Date","values":["2007-10"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Optoelectronics Research Centre (pre 2011 reorg)","Optoelectronic Research Center"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Southampton"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://eprints.soton.ac.uk/50699/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://eprints.soton.ac.uk/50699/1/Wellington_2007_thesis_4037.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis presents results from fabrication of UV direct write structures in lithium niobate and lithium tantalate. Unassisted direct writing of surface channel waveguides using lambda = 244 nm cw light resulted in polarisation specific waveguides fabricated on z- cut crystals. Waveguides were characterised using mode profiles, propagation losses, numerical aperture and refractive index measurements. In z-cut congruent lithium niobate, waveguides were written on the +z and -z faces producing structures that guided TM polarisation only with +z face waveguides exhibiting the lowest propagation loss of ~ 2 dB/cm, a maximum refractive index difference of ~ 8 x 10<sup>-4</sup> and a mean lifetime tau of ~ 4.5 days. The waveguiding mechanism is believed to be due to a lithium out-diffusion enhanced by a transient photorefractive effect. Waveguides were also written in stoichiometric and doped samples to test improvements in waveguide lifetimes. Surface domain reversal was observed in congruent lithium niobate on both +z and -z faces. Channel waveguides written into lithium tantalate were characterised and compared with lithium niobate.<br/><br/>Surface ferroelectric domain reversal via illumination of single pulsed lambda = 266 nm light through a phasemask on +z face congruent lithium niobate produced ordered alignment of domain lines along the crystallographic y-axes with minimum domain separation width of ~ 2 μm. Results from high temperature exposures and multipulse regimes are presented and a domain formation mechanism is proposed via an Nb anti-site model."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Direct UV writing of structures in lithium niobate and lithium tantalate"]}]}],"canonical_facts":{"dc:contributor.advisor":["Eason, R.W."],"dc:creator":["Wellington, Iain"],"dc:date":["2007-10"],"dc:date.issued":["2007-10"],"dc:description.abstract":["This thesis presents results from fabrication of UV direct write structures in lithium niobate and lithium tantalate. Unassisted direct writing of surface channel waveguides using lambda = 244 nm cw light resulted in polarisation specific waveguides fabricated on z- cut crystals. Waveguides were characterised using mode profiles, propagation losses, numerical aperture and refractive index measurements. In z-cut congruent lithium niobate, waveguides were written on the +z and -z faces producing structures that guided TM polarisation only with +z face waveguides exhibiting the lowest propagation loss of ~ 2 dB/cm, a maximum refractive index difference of ~ 8 x 10<sup>-4</sup> and a mean lifetime tau of ~ 4.5 days. The waveguiding mechanism is believed to be due to a lithium out-diffusion enhanced by a transient photorefractive effect. Waveguides were also written in stoichiometric and doped samples to test improvements in waveguide lifetimes. Surface domain reversal was observed in congruent lithium niobate on both +z and -z faces. Channel waveguides written into lithium tantalate were characterised and compared with lithium niobate.<br/><br/>Surface ferroelectric domain reversal via illumination of single pulsed lambda = 266 nm light through a phasemask on +z face congruent lithium niobate produced ordered alignment of domain lines along the crystallographic y-axes with minimum domain separation width of ~ 2 μm. Results from high temperature exposures and multipulse regimes are presented and a domain formation mechanism is proposed via an Nb anti-site model."],"dc:format":["text"],"dc:identifier.uri":["https://eprints.soton.ac.uk/50699/1/Wellington_2007_thesis_4037.pdf"],"dc:publisher.department":["Optoelectronics Research Centre (pre 2011 reorg)","Optoelectronic Research Center"],"dc:publisher.institution":["University of Southampton"],"dc:relation.isreferencedby":["https://eprints.soton.ac.uk/50699/"],"dc:title":["Direct UV writing of structures in lithium niobate and lithium tantalate"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T04:35:50Z"}