25 research outputs found
On-chip spatiotemporal optical vortex generation using an integrated metal-dielectric resonator
We theoretically demonstrate the possibility of generating a spatiotemporal
optical vortex (STOV) beam in a dielectric slab waveguide. The STOV is
generated upon reflection of a spatiotemporal optical pulse from an integrated
metal-dielectric structure consisting of metal strips "buried" in the
waveguide. For describing the interaction of the incident pulse with the
integrated structure, we derive its "vectorial" spatiotemporal transfer
function (TF) describing the transformation of the electromagnetic field
components of the incident pulse. We show that if the TF of the structure
corresponds to the TF of a spatiotemporal differentiator with a phase
difference between the terms describing temporal and spatial differentiation,
then the envelope of the reflected pulse will contain an STOV in all nonzero
components of the electromagnetic field. The obtained theoretical results are
in good agreement with the results of rigorous numerical simulation of the STOV
generation using a three-strip metal-dielectric integrated structure. We
believe that the presented results pave the way for the research and
application of STOV beams in the on-chip geometry.Comment: 14 pages, 5 figure
Multifocal diffractive lens generating several fixed foci at different design wavelengths
We propose a method for designing multifocal diffractive lenses generating prescribed sets of foci with fixed positions at several different wavelengths. The method is based on minimizing the difference between the complex amplitudes of the beams generated by the lens microrelief at the design wavelengths, and the functions of the complex transmission of multifocal lenses calculated for these wavelengths. As an example, a zone plate generating three fixed foci at three different wavelengths was designed, fabricated, and experimentally investigated. The proof-of-concept experimental results confirm the formation of foci with fixed positions at the design wavelengths. The obtained results may find applications in the design and fabrication of novel multifocal contact and intraocular lenses with reduced chromatic effects