1,720,970 research outputs found
UV written waveguides for photonic quantum circuits
No full textIntegrated optical circuits provide an important technology within optical telecommunications, and are also major subjects of research in optical chemical and biological sensors. Recently, however, their application in quantum information processing has attracted considerable attention within the research community, as they offer a robust and reliable route to realising experiments on a chip that would require whole optical benches of bulk optics. This talk will provide a background to technologies for creating optical circuitry, review their existing uses within optics, will look at the elements required to achieve meaningful quantum operations, and will highlight the recent uses of laser direct write to create optical waveguides. In particular, the UV direct write approach pioneered at COM in Denmark and at the ORC in Southampton will be shown to allow the creation of low loss, fibre compatible waveguides, enables the fabrication of cross-couplers and allows ready incorporation of Bragg gratings, thermo-optic elements and liquid crystal tunable elements. Results from the application of UV written waveguides to quantum circuits will be presented
Simple planar Bragg grating devices for photonic Hilbert transform
No full textHilbert transformers are important devices widely used in information processing and signal analysis in the electronic domain. For example, for spectral efficiency improvement, it is used to construct the analytic signal for single sideband (SSB) modulation from a real signal. Photonic Hilbert transformers (PHTs) are proposed for a similar range of applications and would allow the direct processing of optical signals at bandwidths far beyond current electronic technologies
All-optical signal processing using planar Bragg gratings
No full textThe fabrication techniques of Bragg gratings broadly fall into two categories: that are holographic, and that are non-interferometric, based on the periodical UV radiation along the photosensitive medium. The fabrication technique in this work is the direct UV grating writing (DGW). This method involves focusing two crossed laser beams (lambda=244nm) into a photosensitive core layer. Precise translation of the sample and modulation of the interference pattern define the channel waveguide and simultaneously create grating structures, shown in Figure 1. First developed at Optoelectronics Research Centre in 2002, it has similarities to the UV writing techniques used for fiber Bragg grating inscription. Advanced grating properties such as chirp, phase shifts, and apodisation are introduced by adjusting the laser intensity and the translating speed
UV written planar Bragg grating sensors: geometries and applications
No full textBragg gratings in optical fibres are a well developed technology that finds many applications in photonics, including wavelength stabilization, dispersion compensation, and use as temperature and strain sensors. In recent years we have developed planar Bragg grating devices as integrated counterparts to fibre based devices[1]. The implementation of Bragg gratings in planar opens many new degrees of freedom because it is possible to make more intricate circuits incorporating splitters, interferometers, couplers, etc
Realisation of photonic Hilbert transformer with a simple planar Bragg grating
No full textPhotonic Hilbert transformers (PHTs) are desirable for the direct processing of optical signals at high speeds and operation bandwidths, allowing optical networks to outperform current electronic technologies. We practically demonstrate a photonic Hilbert transformer in planar geometry; utilising a pi-phase shift planar Bragg grating with proper apodization profile. The device is fabricated by direct UV grating writing technology in silica-on-silicon [1]. The PHT has a pi-phase shift at the zero point of the frequency response, whereas the amplitude remains constant. The pi-phase shift in PHT is simply induced by placing a pi-phase shift in the refractive index modulation. The constant amplitude is achieved by precise apodization of the grating coupling strength, while the apodization profile is given by [2]. With our current direct UV writing technology, the proposed grating can be fabricated in a much higher accuracy then the conventional fibre Bragg grating manufacturing technique. We will present our latest work on more complex apodized gratings to obtain the ideal realisable frequency and temporal responses for PHTs
Direct UV writing at the University of Southampton - substrates, structures and sensors
No full textWe present our recent developments on direct-UV-written planar lightwave circuits (PLCs) based on applications in telecommunications, material characterisation and optical sensing. Interfering two focussed UV spots provides us with an unique capability to simultaneously define channel waveguides and Bragg gratings [1] in a multifunctional silica-on-silicon PLC chip (Figure 1a). This opens new device and application opportunities for laser-based processing. In particular, we have created a range of refractive index sensors and modulators by accessing the evanescent field of our planar Bragg gratings, incorporating functionalised surface chemistry to demonstrate chemical [2] and biological sensing capabilities [3], or liquid crystals to provide electrical wavelength tuning and selectivity [4]
UV-written planar chirped Bragg gratings for use in dispersion management
No full textWe demonstrate for the first time experimental results of chirped and chirp-apodized Bragg gratings written into planar substrates. The gratings are written using Direct Grating Writing, allowing both buried channels and gratings to be defined simultaneously. The experimental results are then compared to theory and agree well with predicted spectra
Realization of a planar Bragg grating for all-optical Hilbert transformer
No full textAn all-optical Hilbert transformer is proposed and demonstrated experimentally. We preliminarily show that an all optical Hilbert transformer can be implemented using an apodized planar Bragg grating with a single pi phase-shift. The proposed planar Bragg grating is fabricated by Direct UV writing technology in silica-on-silicon
Line defects and temperature effects in liquid crystal tunable planar Bragg gratings
No full textLiquid crystal tunable planar Bragg Gratings produced by Direct UV Writing are capable of wavelength tuning of over 100GHz. However, such devices exhibit non-linear tuning curves with threshold points and hysteresis. We show that these effects are due to the formation of disclination structures in the liquid crystal and discuss the role of electrode defects and sample temperature on wavelength tuning
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