1,721,218 research outputs found
Integrated planar Bragg grating sensors: Towards an oxygen sensor
No full textSensors play an important role in measuring changes in the environment. Optical sensors operating at well established telecoms wavelengths demonstrate many benefits over electronic sensors. These include immunity to EM interference, absence of spark risk in flammable environments and remote interrogation of large arrays over many tens or even hundreds of kms
Structured nonlinear crystals for visible light generation in displays and bio-sciences
No full textNonlinear conversion of diode based sources using MgO doped PPLN provides a viable route to watt level power visible laser wavelength systems with high electrical efficiency and offer a low cost solution for applications in laser projection and bio-optics. Recent developments of superior nonlinear materials together with brighter and more powerful diode sources provide an excellent opportunity for optical technology over the coming decade
Quasi-phasematching for wavelength conversion and all-optical nonlinear processing
No full textThis course provides an overview and grounding in the use of quasi-phase matched materials in nonlinear optics. Quasi-phase matching (QPM) is emerging as a dominant technology for nonlinear optical frequency conversion in the visible and near-IR. By offering a large nonlinear susceptibility, non-critical phase matching and a tailored spectral response, it is allowing a wide range of new optical devices to be realized. The course will start by explaining the underlying concepts of QPM and reviewing the available materials, their advantages and disadvantages. Both bulk and waveguide QPM devices will be covered. The course will make use of worked examples of real devices that will be presented to explain their operation. These examples will draw on experiments in harmonic generation, fiber-pumped OPOs, and telecomm wavelength conversion in waveguide PPLN. The commercial and scientific uses of QPM devices will be reviewed. Finally, the market potential of QPM devices will be discussed. The markets and opportunities in telecommunications, infra-red countermeasures, scientific, and displays will be considered
Quasi-phasematching for wavelength conversion and all-optical nonlinear processing
No full textThis course provides an overview and grounding in the use of quasi-phase matched materials in nonlinear optics. Quasi-phase matching (QPM) is emerging as a dominant technology for nonlinear optical frequency conversion in the visible and near-IR. By offering a large nonlinear susceptibility, non-critical phase matching and a tailored spectral response, it is allowing a wide range of new optical devices to be realized. The course will start by explaining the underlying concepts of QPM and reviewing the available materials, their advantages and disadvantages. Both bulk and waveguide QPM devices will be covered. The course will make use of worked examples of real devices that will be presented to explain their operation. These examples will draw on experiments in harmonic generation, fiber-pumped OPOs, and telecomm wavelength conversion in waveguide PPLN. The commercial and scientific uses of QPM devices will be reviewed. Finally, the market potential of QPM devices will be discussed. The markets and opportunities in telecommunications, infra-red countermeasures, scientific, and displays will be considered
UV written waveguides: applications in telecoms and sensors
No full textIn recent years, ultra-violet laser direct writing has been recognized as a technique that provides a powerful way of creating integrated optical devices. We will describe the developments in this field, concentrating on the use of two-beam writing to create Bragg gratings in planar integrated format. In this paper we will show how our UV writing technique can be used to fabricate structures required in a wide range of applications, from the creation of wide-band couplers, through to highly sensitive integrated sensor devices. The direct computer control in UV direct writing removes many of the constraints that normally limit planar integrated optics. In particular, it dispenses with the photolithography and etching steps traditionally required to make low-loss waveguide devices. The work reported will show how this flexibility of UV writing may be enhanced by using novel substrate structures that allow new device types. Results will be presented on Bragg grating sensors for solvent purity, biological layer measurement, phase changes and strain. Further results will include a demonstration of Liquid Crystal tuned Bragg grating devices yielding greater than 100GHz spectral tuning. Novel substrate configurations include a flat-fibre geometry based on MCVD fibre preform manufacture allowing devices with millimetre scale widths and 10s of cm lengths
Precision dicing of optical materials
Full text linkDuctile regime dicing has been used to machine a variety of optical materials to produce waveguides for lasers, multi-mode interference devices and non-linear devices. However, few papers discuss the properties of the machining, either qualitatively or quantitatively. In this work ductile regime dicing of germanium, Yttrium Aluminum Garnet (YAG), lithium niobate and silicon for photonic applications are reported. Machining parameters are discussed, surface micrographs shown, and surface roughnesses are calculated for each sidewall machined. The sidewall average surface roughnesses (Sa) were measured to be 2.1 nm for germanium, 3.5 nm for YAG, 7.9 nm for lithium niobate and 8.6 nm for silicon
Picosecond Ti:sapphire-pumped optical parametric oscillator based on periodically-poled LiNbO<sub>3</sub>
No full textA low threshold OPO has been developed with tuning from 1.15 to 2.45µm as the Ti:sapphire pump laser is tuned from 790 to 810nm. Output powers up to 130mW have been achieved at 75% pump depletion
Contact electrode method for bulk periodically poled LiNbO<sub>3</sub>
No full textOver the past few years, there has been increasing interest in the use of quasi-phase-matched (QPM) nonlinear crystals, which permit noncritical-phase-matching for any wavelengths in the transparency range of the crystal, and have the advantage of using the largest component of the nonlinear susceptibility tensor, one that is not available in birefringent phase matching without walk-off problems. QPM can be achieved by an appropriate periodic modulation of the nonlinear coefficient, which corresponds to periodic domain reversal in ferroelectric materials. In particular, the application of QPM to bulk nonlinear optics has been revolutionised by the emergence of electric field poling techniques for patterning the domain structure of ferroelectric and polar crystals. In all the reported fabrication processes the periodic electrode (consisting of resist and/or metal layers) has been fabricated on the surface of the crystal substrates by conventional photolithography.We report here a new fabrication process for PPLN - the contact electrode method (CEM) - in which the periodic electrode is pressed onto one of the substrate surfaces with a uniform electrode on the other. CEM does not need any photolithographic processes on the substrate surface which may lead to greatly reduced fabrication cost. Furthermore, CEM would be applicable for fabrications of periodically poled glass fiber
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