1,721,060 research outputs found
Novel active waveguide devices in direct-bonded structures
No full textThis thesis describes a series of experimental studies on the use of direct bonding for optical waveguide fabrication. The direct bonding technique involves contacting two ultra-clean polished surfaces to form an adhesive-free vacuum-tight bond. Optical materials bonded in this way can be formed into waveguide devices, and this work extends direct bonding to include periodically poled materials and a new solid-state ion-exchange process. The first result of this work describes the fabrication of a 5.5-mm-long, 12-µm-thick periodically poled LiNbO3 planar waveguide buried in LiTaO3. Frequency doubling experiments performed with this device demonstrate a conversion efficiency of 4.3 %W-1, a value 40% greater than that calculated for an optimised bulk device of similar length.Also demonstrated is a photorefractive iron-doped LiNbO3 waveguide buried in non-photorefractive magnesium-doped LiNbO3. In optical limiting experiments this device demonstrates a change in optical density of 2 and photorefractive response time of 5 milliseconds, representing 20 times greater optical limiting and 60 times faster operational speed than the bulk material. K+-Na+ ion-exchange between direct-bonded glass layers is studied and used as a novel solid-state technique for waveguide fabrication. This process is also developed to incorporate direct-UV-written channel waveguides in an ion-exchanged buried photosensitive glass layer. Finally, operation of a single-mode channel waveguide laser in neodymium-doped photosensitive SGBN glass (based on a composition of silica, germania, boron, and sodium) is demonstrated, with propagation losses of < 0.3 dB cm-1 and milliwatt-order lasing thresholds. <br/
Ductile dicing of LiNbO<sub>3</sub> ridge waveguide facets to achieve 0.29 nm surface roughness in single process step
No full textA single-step ductile dicing process capable of manufacturing optical quality facets in lithium niobate (LiNbO3) ridge waveguides with an average surface roughness of 0.29 nm is reported. This result is comparable with surface roughnesses achieved by lapping and polishing and represents an order of magnitude improvement over the prior state of the art in LiNbO3 waveguide facet dicing
New approach to fabricating channel waveguides in z-cut PPLN using zinc-diffusion
No full textHigh-yield zinc-diffused channel waveguides in pre-poled z-cut PPLN with high photorefractive resistance at room temperature are presented. Frequency doubling of a 1064nm Nd:YAG laser at 145°C gave a conversion efficiency of 16.7%/Wcm
Direct UV writing of channel waveguides and Bragg grating structures
No full textDirect UV writing is a dynamic planar lightwave circuit fabrication technique offering great potential as a means of rapid prototyping and small/medium batch fabrication. The technique is based on the refractive index increase of photosensitive glasses through exposure to ultraviolet light. In this case, a beam is tightly focused to create a writing spot in the order of microns and is translated relative to the sample. It is this translation over a 2-d plane that defines the channel waveguide structures; there is no need for a photolithographic mask or subsequent processing. This process has previously been shown to be a versatile system producing good quality, low loss waveguides compatible with existing silica based telecom fibres
Non-reciprocal transmission in a direct-bonded photorefractive Fe:LiNbO<sub>3</sub> waveguide buried in MgO:LiNbO<sub>3</sub>
No full textWe report a 20µm-thick Fe:LiNbO3 waveguide buried in MgO:LiNbO3 by direct bonding. Non-reciprocal transmission measurements in a 3mm-long device with a cw 532nm source gave a relative change in optical density of 2 and response time of 4-5 milliseconds
2D hexagonal poling for nonlinear photonic crystals and quasicrystals in LiNbO<sub>3</sub>
No full textWe report on the fabrication of bidimensional arrays of hexagonal domains with strictly periodic and quasi-periodic patterns for the implementation of nonlinear photonic crystals and quasi-crystals in z-cut congruent LiNbO3
Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition
No full textA sensor believed to be the first truly integrated optical sensor capable of detecting the liquid-solid phase transition of water is presented. The condensation, freezing, melting and evaporation of water are all detected with a planar silica Bragg grating operating in the 1.5 µm telecommunications window. Additionally, use of the sensor allows recognition of supercooled liquid at temperatures below the melting point of water. The device, well suited for integrated optics, is fabricated by direct UV writing with simultaneous definition of the grating. The Bragg grating is exposed and water is allowed to condense over it. Interaction with the evanescent field causes small changes in effective index (5 x 10-6) which can be detected, a sufficient sensitivity to identify the phase transitions of water clearly
Fabrication of a single mode laser by UV-writing in neodymium doped silica-on-silicon
No full textWe describe the fabrication of a waveguide laser by UV-writing in neodymium doped silica-on-silicon. The substrate is fabricated by Flame Hydrolysis Deposition and solution doping techniques. Lasing at 1048-1056nm was observed with a slope efficiency of 33% and threshold of 4mW for the transition. Lasing was also observed at 1356nm
Quantitative determination of photosensitivity proximity effects in multi-exposure direct UV writing for high density integrated optics
No full textUV direct writing is used to write planar channel waveguide gratings and simultaneously investigate photosensitivity proximity effects. Increases are seen up to 9µm away from the initial exposure with maximum effective index increase of 8.3 x 10-4
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