Optical integration for microfluidic systems

Integrated optical waveguides offer great potential for constructing sensors and sorters for integrated optofluidic devices in low-cost on-chip systems. Progress towards optical integration for bioanalysis will be discussed, with examples in key applications, and challenges and opportunities will be described

Simple evanescent field sensor for NIR spectroscopy

Near-Infrared (NIR) spectroscopy is a powerful tool for chemical analysis in applications ranging from biomedicine to analysis of food products and textiles [1]. However, molar absorptivities in this spectral region are usually weak, so that high-sensitivity measurement devices are required. Optical waveguides provide for highly sensitive attenuated total reflection (ATR) spectroscopy in a robust mass-producible format, and allow for ultra-small sample volume, due to the 100 nm scale extent of the evanescent field, and the potential for lab-on-chip integration

Optical waveguide manipulation of micro- and nano-spheres

Optical tweezers are well-established as a tool for non-contact, non-destructive handling of biological materials [1] and of inorganic nanospheres attached to biological molecules [2]. Recently, interest has grown in optical manipulation at surfaces [3] potentially as part of the toolbox of the "lab-on-a-chip". In particular, advances have been made in trapping and propulsion of metallic and dielectric micro- and nano-particles in the evanescent fields of optical waveguides [4,5], which may form part of a planar microsystem into which optical detection and spectroscopy of separated species could also be integrated. Optical waveguides embedded in surfaces represent a powerful means of controlling the distribution of optical intensity and intensity gradient at such surfaces, for particle control. In this paper, the design of optical waveguides and waveguide devices for trapping, propulsion and sorting of gold nanospheres and latex microspheres [6,7] will be described and recent experimental results presented and compared with theoretical models. The implications of these results for some proposed applications in the biosciences will be discussed

Optical waveguide devices for bioanalysis

Integrated optical waveguides offer great potential as versatile platforms for constructing advanced biosensors, optical cell-sorters and integrated optofluidic systems, exploiting the technological approaches of microelectronics and guided-wave optics to realise low-cost on-chip systems. Progress towards optical integration in microsystems for bioanalysis will be discussed, with examples in key applications, and challenges and opportunities will be described

High reflectivity Bragg gratings fabricated by 248nm excimer laser holographic ablation in thin Ta₂O₅ films overlaid on glass waveguides

Relief Bragg grating reflectors inscribed on channel waveguides may be used in optical communications as add-drop wavelength multiplexers, gain-flattening filters, distributed feedback laser mirrors, or in sensing technology as high sensitivity devices for precise monitoring of chemical or biomedical processes. We present strong Bragg grating reflectors in Ta2O5 thin oxide films overlaid on potassium ion exchanged channel waveguides in BK-7 glass, inscribed using 248nm excimer laser holographic ablation. The grating pattern was created employing two-beam interference using a modified Mach-Zehnder interferometric cavity and the output of a narrow-lined injection cavity 248nm excimer laser. The experimental data presented are divided into two sections: the first section refers to the study of the grating ablation process of thin Ta2O5 films with respect to the exposure conditions; and the second focuses in the implementation of those relief grating in functional waveguide devices

Ytterbium-doped tantalum pentoxide waveguides: spectroscopy for compact waveguide lasers

Ytterbium-doped materials are common gain media in high-performance laser systems. In this work, the first spectroscopic investigation of ytterbium-doped tantalum pentoxide (Yb:Ta2O5) for compact waveguide laser applications is presented

Simultaneous poling and planar waveguide fabrication in glasses

Fabrication of buried planar waveguides with 2nd order nonlinear susceptibility in the upper cladding is carried out in soda-lime and BK7 glass substrates in one step by thermal poling

Waveguide lasers operating at 1084nm in neodymium-diffused lithium niobate

We report the demonstration of waveguide lasers in lithium niobate into which the active element neodymium has been introduced by thermal diffusion. The waveguides were fabricated using conventional Ti indiffusion, and optical feedback was provided by the polished endfaces alone. The absorbed power threshold of one waveguide laser was estimated at 13±3 mW for pumping at 814 nm, and its slope efficiency in terms of total lasing output as a function of absorbed pump power was estimated to be 55±8%. Laser output powers in excess of 100 mW were observed

New configurations and novel fabrication of optical microresonators

Optical passive and active microresonators are versatile optical devices and show the potential to become compact building blocks in larger integrated systems performing key optical signal processing functions such as wavelength filtering, switching, regeneration, and buffering. Some of these functions find already widespread use in novel optical sensor arrangements and can be potentially employed in future advanced telecom systems. Various microresonator geometries have been studied each with associated unique characteristics. We have recently fabricated two novel optical microresonators namely the "microdiscus" and the "microbottle", and studied their performance (1,2). This abstract briefly describes the fabrication and preliminary characterization of the microresonators and the detailed results and analysis will be presented at the conference

Chalcogenide microsphere fabricated from fibre taper-drawn using resistive heating

Over the last decade extreme interest for microsphere resonators has increased rapidly due to their very high quality Q factors, the ease with which they can be manufactured and their versatility in terms of materials and dopants for plenty of passive and active devices. Furthermore, microsphere resonators have the potential to add significant functionality to planar lightwave circuits when coupled to waveguides where they can provide wavelength filtering, delay and low-power switching, and laser functions [1].Recently, chalcogenides are rapidly establishing themselves technologically superior materials for emerging application in non-volatile memory and high speed switching [2] and have been considered for a range of other optoelectronic technologies. Chalcogenide glasses offer a wide wealth of active properties, an exceptionally high nonlinearity, photosensitivity, the ability to be doped with active elements including lanthanides and transitional metals and are able to form detectors, lasers and amplifiers and offer semiconductor, optical, acousto-optic, superconducting and opto-mechanical properties. Unlike any other optical material, they have been formed in to a multitude of form: such as optical fibres, thin films, bulk optical components, microsphere resonators, metamaterials and nanoparticles, patterned by CMOS compatible processing at the sub micron scale. To date, most studies on microsphere resonators have utilized silica microspheres fabricated by melting the tip of an optical fibre with the resulting stem attached to the microsphere used as a tool to place the sphere in the required location while characterizing the microsphere. In this paper high quality chalcogenide (As2S3) microspheres with diameters down to 74 µm are directly fabricated from the taper-drawn using a resistive heating process. A reasonable high quality factor greater than 105 near the wavelength of 1550 nm is demonstrated with an efficient coupling using a fibre taper with a diameter of 2 µm