189,219 research outputs found
Cavities with Non-Spherical Mirrors for Enhanced Quantum Emitter-Cavity Photon Interaction
No full textThis dataset contains the results of numerical simulations supporting the corresponding article in Physical Review A "Cavities with Non-Spherical Mirrors for Enhanced Quantum Emitter-Cavity Photon Interaction" by D.V. Karpov and P. Horak.
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Feasibility study of SOA-based noise suppression for spectral amplitude coded OCDMA
No full textWe investigate the benefits of employing a saturated SOA to reduce optical noise in an incoherent light OCDMA system. In the context of spectrum-slicing, SOA-based noise suppression has shown significant potential for enhancing the signal quality of noisy light. In this paper, we evaluate the viability of the technique for spectral amplitude coded OCDMA, and show that the benefits of SOA-based noise suppression do not extend readily to this application, due to post-SOA optical filtering effects at the receiver. However, appreciable performance improvements can in principle be realized through optimized system and decoder design
Dataset for "Efficiency and intensity noise of an all-fiber optical parametric oscillator"
No full textDataset for article "Efficiency and intensity noise of an all-fiber optical parametric oscillator" by I. Begleris and P. Horak, accepted for publication in Journal of the Optical Society of America B (2019)
The set contains all the raw data generated by computer simulations that are analysed and plotted in the paper.</span
Dataset for Frequency-banded nonlinear Schrödinger equation with inclusion of Raman nonlinearity
No full textThis repository holds the data published in the paper:
Begleris, I., & Horak, P. (2018). Frequency-banded nonlinear Schrödinger equation with inclusion of Raman nonlinearity. Optics Express, 26(14).
The data is proof of the argument of the viability and efficiency of the Banded nonlinear Schrödinger equation against the Generalised nonlinear Schrödinger equation.</span
Efficient optomechanical cooling in one-dimensional interferometers
No full textWe present a scattering model which enables us to describe the mechanical force, including the velocity dependent component, exerted by light on polarizable massive objects in a general one-dimensional optical system. We show that the light field in an interferometer can be very sensitive to the velocity of a moving scatterer. We construct a new efficient cooling scheme, ‘external cavity cooling’, in which the scatterer, that can be an atom or a moving micromirror, is spatially separated from the cavity
Dataset for: Designing silicon-core fiber tapers for efficient supercontinuum generation in the greenhouse has absorption region
No full textDataset supports: Campling, J, Horak, P. & Peacock, A.C. (2020).Designing silicon-core fiber tapers for efficient supercontinuum generation in the greenhouse gas absorption region. Journal of the Optical Society of America B</span
Multimode nonlinear fibre optics: theory and applications
No full textOptical fibres have been developed as an ideal medium for the delivery of optical pulses ever since their inception (Kao & Hockham, 1966). Much of that development has been focused on the transmission of low-energy pulses for communication purposes and thus fibres have been optimised for singlemode guidance with minimum propagation losses only limited by the intrinsic material absorption of silica glass of about 0.2dB/km in the near infrared part of the spectrum (Miya et al., 1979). The corresponding increase in accessible transmission length simultaneously started the interest in nonlinear fibre optics, for example with early work on the stimulated Raman effect (Stolen et al., 1972) and on optical solitons (Hasegawa & Tappert, 1973). Since the advent of fibre amplifiers (Mears et al., 1987), available fibre-coupled laser powers have been increasing dramatically and, in particular, fibre lasers now exceed kW levels in continuous wave (cw) operation (Jeong et al., 2004) and MW peak powers for pulses (Galvanauskas et al., 2007) in all-fibre systems. These developments are pushing the limits of current fibre technology, demanding fibres with larger mode areas and higher damage threshold. However, it is increasingly difficult to meet these requirements with fibres supporting one single optical mode and therefore often multiple modes are guided. Non-fibre-based laser systems are capable of delivering even larger peak powers, for example commercial Ti:sapphire fs lasers now reach the GW regime. Such extreme powers cannot be transmitted in conventional glass fibres at all without destroying them (Gaeta, 2000), but there is a range of applications for such pulses coupled into hollow-core capillaries, such as pulse compression (Sartania et al., 1997) and high-harmonic generation (Rundquist et al., 1998). For typical experimental parameters, these capillaries act as optical waveguides for a large number of spatial modes and modal interactions contribute significantly to the system dynamics.In order to design ever more efficient fibre lasers, to optimise pulse delivery and to control nonlinear applications in the high power regime, a thorough understanding of pulse propagation and nonlinear interactions in multimode fibres and waveguides is required. The conventional tools for modelling and investigating such systems are based on beam propagation methods (Okamoto, 2006). However, these are numerically expensive and provide little insight into the dependence of fundamental nonlinear processes on specific fibre properties, e.g., on transverse mode functions, dispersion and nonlinear mode coupling. For such an interpretation a multimode equivalent of the nonlinear Schrodinger equation, the standard and highly accurate method for describing singlemode nonlinear pulse propagation (Agrawal, 2001; Blow & Wood, 1989), is desirable. In this chapter, we discuss the basics of such a multimode generalised nonlinear Schrodinger equation (Poletti & Horak, 2008), its simplification to experimentally relevant situations and a few select applications. We start by introducing and discussing the theoretical framework for fibres with χ(3) nonlinearity in Sec. 2. The following sections are devoted to multimode nonlinear applications, presented in the order of increasing laser peak powers. A sample application in the multi-kW regime is supercontinuum generation, discussed in Sec. 3. Here we demonstrate how fibre mode symmetries and launching conditions affect intermodal power transfer and spectral broadening. For peak powers in the MW regime, self-focusing effects become significant and lead to strong mode coupling. The spatio-temporal evolution of pulses in this limit is the topic of Sec. 4. Finally, at GW peak power levels, optical pulses can only be delivered by propagation in gases. Still, intensities become so high that nonlinear effects related to ionisation must be taken into account. An extension of the multimode theory to include these extreme high power effects is presented in Sec. 5 and the significance of mode interaction is demonstrated by numerical examples pertaining to a recent experiment. Finally, we end this chapter with conclusions in Sec. 6
Fiber optics for quantum computers
No full textWe describe schemes for the integration of miniature optical components onto Atom Chips, for the manipulation and detection of ultra-cold atoms. Our intention is to build detectors sensitive enough to accurately detect single atoms. Two approaches are discussed: simple fluorescence detection and the use of a resonant cavity. Theory predicts that cavities with F>100 should be sufficient to obtain signal to noise ratios high enough to detect single atoms. The first micro cavities were demonstrated using mirrors formed by cleaved fiber ends coated with a stick-on dielectric coating to give F ~100. A more successful approach involves the full integration of the mirrors and fibers by using Bragg gratings written into the fiber core: it has been possible to form gap cavities with F ~ 150
The role of squeezing in quantum key distribution based on homodyne detection and post-selection
No full textThe role of squeezing in quantum key distribution with continuous variables based on homodyne detection and post-selection is investigated for several specific eavesdropping attacks. It is shown that amplitude squeezing creates strong correlations between the signals of the legitimate receiver and a potential eavesdropper. Post-selection of the received pulses can therefore be used to reduce the eavesdropper's knowledge of the raw key, which increases the secret key rate by orders of magnitude over large distances even for modest amounts of squeezing
Experimental demonstration of a high-flux capillary based XUV source in the high ionisation regime
No full textHigh harmonic generation (HHG) has proven to be a fascinating and incredibly useful nonlinear optical phenomenon and has led to the realisation of tabletop sources of coherent extreme ultraviolet (XUV) radiation. Capillary based geometries in particular have attracted a great deal of attention due to their lengthy interaction regions and the potential to phase-match the HHG process leading to a large increase in XUV flux. Unfortunately due to plasma induced nonlinear and dispersive effects the simple phase-matching mechanism detailed in [1] cannot be scaled to high energy pump pulses and high gas pressures. In this work we have used a computational model [2] to design a capillary that can support a broad interaction region well-suited to quasi-phase-matching (QPM) while simultaneously reducing the effect that XUV reabsorption has on the output flux of the source. This modelling work has involved adjusting both the capillary length and gas density profile (figure 1a) in order to produce rapid oscillations in the radially integrated ionization fraction (figure 1b) coupled with a rapid decrease in gas pressure at the capillary exit. Our theory suggests that these oscillations are driven by a nonlinear self-compression process modulating the intensity of the pump pulse as it propagates through the plasma-filled waveguide [3]. Subsequent experimental work has shown an increase in XUV flux of almost 50 times over our previous capillary-based source (see figure 1c), and preliminary estimates suggest a photon flux of 1012 photons s-1 harmonic-1 in the 45 eV spectral region
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