We investigate the impact of the wavelength dependence of the discrete diffraction on the dynamics of Light Bullets (LBs) in a periodic medium. This dependence gives rise to a strong spatiotemporal coupling, which in turn leads to a spatiotemporally modified LB spectrum. This nonlinear spectral reshaping is measured and analyzed. It is found numerically and in experiment that it can be used to measure the strength of spatiotemporal coupling.
In this paper, the authors extend the theory of cascaded Kerr to the case of pulses propagating in a dispersion tuned optical fibre generating a strongly mismatched third harmonic wave. This model includes the nonlocal response due to group velocity mismatch and different levels of dispersion for the fundamental and the third harmonic. The nonlocal harmonic approximation was applied to the system of coupled equations and derive a perturbed nonlinear Schrodinger equation for the fundamental wave only. The perturbation was shown to have the functional structure of a 5th order Kerr effect with a phase shift dependent on the square of the intensity. The dispersion features of the system create a non-instantaneous response of the perturbation, which can act similarly to a higher order Raman response with a mean time delay of tuneable magnitude and sign.
The Planet Formation Imager (PFI) project aims to image the period of planet assembly directly, resolving structures as small as a giant planet's Hill sphere. These images will be required in order to determine the key mechanisms for planet formation at the time when processes of grain growth, protoplanet assembly, magnetic fields, disk/planet dynamical interactions and complex radiative transfer all interact - making some planetary systems habitable and others inhospitable. We will present the overall vision for the PFI concept, focusing on the key technologies and requirements that are needed to achieve the science goals. Based on these key requirements, we will define a cost envelope range for the design and highlight where the largest uncertainties lie at this conceptual stage.
By means of a time-resolved, shadowgraphic method we observed directly the development of the pulse-splitting dynamics of a femtosecond laser pulse propagating in the filamentary regime in water. For the first time to our knowledge, the relative splitting velocity was measured. We compare the experimental data with numerical simulations. A possible scenario for the splitting event and evolution of the fragments is discussed.
Summary form only given. We show that a new type of nondiffracting and nondispersing nonlinear waves exist also for normal group velocity dispersion (GVD). Being the natural eigenmodes of the system, we believe that they are the key to understanding experiments where the diffraction, dispersion, and nonlinear length scales are comparable. Specifically, we consider the usual NLS model which describes the paraxial propagation of pulsed beams in Kerr media. In order to demonstrate the generality of X-waves as space-time localized solutions for normal GVD, we have extended our calculations to second-harmonic generation, where symbiotic two-color X-waves are found.
Digital phase front retrieval from inline, Gabor-type holograms has to overcome the challenge of separating the object wave from its conjugate by retrieving the phase of the optical field. Recently, the so-called 'twin image problem' has received revived interest, mainly in conjunction with lens-less digital holography applications in the XUV or X-ray bands. In this context, we propose to use a recently devised algorithm, the iterative shadowgraphy method (ISM), to solve the twin-image problem and use the retrieved phase front for digital holography applications. The algorithm is based on the principle that the measurement of phase gradients, which drive the diffraction process, enable the retrieval of the transverse phase profile of a field by observing its intensity distribution on different propagation planes. We have proven rigorously that for small phase modulated object waves, the algorithm converges to the correct object wavefront using just two snapshots of the propagated intensity field as input. Because the algorithm is akin to a deconvolution algorithm, experimental noise can destabilize the iteration scheme. In this work, we discuss the influence of noise in the ISM and apply a wavelet-based scheme to regularize the data. We show that the phase retrieved from two experimental, defocused pictures of a weakly absorbing, scattering object can be used to accurately reconstruct the object trough numerical back-propagation. Thus we prove that ISM is suitable for digital holography applications. We compare the ISM to various other schemes, such as direct backpropagation and the Gerchberg-Saxton algorithm and find that the ISM scheme gives a much improved reconstruction of the phase front.
In this contribution, we review the results of the ALSI project (Advanced Laser-writing for Stellar Interferometry), aimed at assessing the potential of ultrafast laser writing to fabricate mid-infared integrated optics (IO) devices with performance compatible with an implementation in real interferometric instruments like Hi5 or PFI. Waveguides for the L, L' and M bands with moderate propagation losses were manufactured in Gallium Lanthanum Sulfide and ZBLAN glasses and used to develop photonic building blocks as well as a full mid-IR 4-telescope beam combiner. We discuss the advantages and disadvantages of the tested combiners and discuss a possible roadmap for the continuation of this work.
Broadly tunable picosecond pulses from the ultraviolet to infrared (370-2497 nm) have been obtained by optical parametric generation and amplification in BiB 3 O 6 . Pulse energies of 48.6 μj at conversion efficiencies as high as 30% have been generated.
We investigate the effects of the space-time coupling (STC) on the nonlinear formation and propagation of Light Bullets, spatiotemporal solitons in which dispersion and diffraction along all dimensions are balanced by nonlinearity, through periodic media with a weak transverse modulation of the refractive index, i.e. waveguide arrays. The STC arises from wavelength dependence of the strength of inter-waveguide coupling and can be tuned by variation of the array geometry. We show experimentally and numerically that the STC breaks the spectral symmetry of Light Bullets to a considerable degree and modifies their group velocity, leading to superluminal propagation when the Light Bullets decay.
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)