Photonic nanojet engineering: focal point shaping with scattering phenomena of dielectric microspheres (original) (raw)
Related papers
Optics Express, 2011
Photonic Nanojets are highly localized wave fields emerging directly behind dielectric microspheres; if suitably illuminated. In this contribution we reveal how different illumination conditions can be used to engineer the photonic Nanojets by measuring them in amplitude and phase with a high resolution interference microscope. We investigate how the wavelength, the amplitude distribution of the illumination, its polarization, or a break in symmetry of the axial-symmetric structure and the illumination affect the position, the localization and the shape of the photonic Nanojets. Various fascinating properties are systematically revealed and their implications for possible applications are discussed.
Photonic nanojet beam shaping by illumination polarization engineering
Optics Communications, 2020
Photonic Nanojets (PNJs) have attracted considerable research attention in the fields of super-resolution optical microscopy, nano-photolithography, and single molecule sensors because of their sub-wavelength near-field focusing properties. In this paper, we thoroughly studied how the polarizations and amplitude profiles of the incident beams affect the shape, size, and location of the PNJs generated from the illuminated microspheres. Numerical results showed that the PNJs generated by microspheres were strongly modulated by the polarizations and amplitude profiles of the illumination beams. Therefore, PNJs can be engineered according to the requirements of a specific application by designing the polarizations and amplitude profiles of the illumination light. Various fascinating properties of the PNJs generated with different illumination schemes were demonstrated and their implications for potential applications were discussed as well.
Direct imaging of photonic nanojets
Optics Express, 2008
We report the direct experimental observation of photonic nanojets created by single latex microspheres illuminated by a plane wave at a wavelength of 520 nm. Measurements are performed with a fast scanning confocal microscope in detection mode, where the detection pinhole defines a diffraction-limited observation volume that is scanned in three dimensions over the microsphere vicinity. From the collected stack of images, we reconstruct the full 3 dimensional photonic nanojet beam. Observations are conducted for polystyrene spheres of 1, 3 and 5 µm diameter deposited on a glass substrate, the upper medium being air or water. Experimental results are compared to calculations performed using the Mie theory. We measure nanojet sizes as small as 270 nm FWHM for a 3 µm sphere at a wavelength λ of 520 nm. The beam keeps a subwavelength FWHM over a propagation distance of more than 3 λ, displaying all the specificities of a photonic nanojet.
Production of photonic nanojets by using pupil-masked 3D dielectric cuboid
Journal of Physics D: Applied Physics, 2017
Photonic nanojets can be created via plane wave irradiation of multi-shaped mesoscale dielectric particles, and a waist of full-width at half-maximum (FWHM) smaller than the diffraction limit can be achieved in this process. In this paper, photonic nanojet produced by a pupil-masked 3D dielectric cuboid lens is numerically investigated under the irradiation of 532 nm wavelength plane wave. It is found that a pupil-masked cuboid lens is not only able to produce photonic nanojets with shorter FWHMs, but also increase its maximal intensity at certain masking ratios on the receiving surface. This phenomenon is different from the result of the spherical-lens reported in previous publications, and is attributed to the convergence of power flow and near-field numerical aperture (NA) increase after analysis of simulated power flow diagrams.
Structured light engineering using a photonic nanojet
Optics letters, 2021
In this Letter, we present the photonic nanojet as a phenomenon in a structured light generator system that is implemented to modify the source focal spot size and emission angle. The optical system comprises a microlens array that is illuminated by a focused Gaussian beam to generate a structured pattern in the far field. By introducing a spheroid with different aspect ratios in the focus of the Gaussian beam, the source optical characteristics change, and a photonic nanojet is generated, which will engineer the far-field distribution. To probe the light fields, we implement a high-resolution interferometry setup to extract both the phase and intensity at different planes. We both numerically and experimentally demonstrate that the pattern distribution in the far field can be engineered by a photonic nanojet. As an example, we examine prolate, sphere, and oblate geometries. An interesting finding is that depending on the spheroid geometry, a smaller transverse FWHM of a photonic na...
Progress In Electromagnetics Research Letters, 2014
Some microobjects can concentrate an incoming incident plane wave and produce the socalled photonic nanojets. The highly focused emerging beams have a high intensity and can be used in applications in microscopy, beam manipulation and imaging. In this article, it is shown that an adequate choice of geometric shape and material can lead to an improvement of the electric field enhancement capacity of nanojets by a factor of 40%.
Transverse and longitudinal confinement of photonic nanojets by compound dielectric microspheres
Proceedings of Spie the International Society For Optical Engineering, 2009
We discuss the compound set of two dielectric microspheres to confine light in a three dimensional region of dimensions on the order of the wavelength when the spheres are illuminated by a plane wave. This simple configuration enables the reduction of the longitudinal dimension of so called photonic jets, together with a strong focusing effect. The beam shaped in that way is suitable for applications requiring high longitudinal resolutions and/or strong peak intensities.
Photonic nanojet-induced modes: fundamentals and applications
Integrated Optics: Devices, Materials, and Technologies XVI, 2012
Photonic nanojet-induced modes (NIMs) have emerged as a new paradigm for understanding the optical properties of chains of dielectric microspheres with wavelength-scale diameters (D≤10λ). Here we show that light focusing and transport properties of chains of submillimeter spheres (D>100λ) are dominated by periodically focused modes (PFMs) which can be considered a geometrical optics analog of NIMs. We review recent geometrical optics results on this subject showing that Brewster angle conditions for TM polarized rays can be periodically reproduced in chains of spheres with index n= 3 =1.73205…. giving rise to lossless PFMs with the 2D period. In this work we studied the phase properties of PFMs using a novel method based on Fourier analysis of the high resolution transmission spectra of chains of submillimeter ruby spheres with n~1.75 at λ=1.2 µm. We demonstrated that PFMs are the best surviving modes in long chains of spheres. Finally, we considered applications of PFMs for focusing multimodal beams in ultra-precise laser surgery.
Journal of the Optical Society of America A, 2005
The detailed optics of photonic nanojets generated by normal plane-wave incidence on dielectric cylinders is discussed. These nanojets have a subwavelength beam waist and propagate with little divergence for several wavelengths. A physical explanation for this peculiar behavior is presented. Characteristic dimensions of the nanojets for a large range of physical parameters are calculated.
Transverse and longitudinal confinement of photonic nanojets by compound dielectric microspheres
Nanophotonic Materials VI, 2009
We discuss the compound set of two dielectric microspheres to confine light in a three dimensional region of dimensions on the order of the wavelength when the spheres are illuminated by a plane wave. This simple configuration enables the reduction of the longitudinal dimension of so called photonic jets, together with a strong focusing effect. The beam shaped in that way is suitable for applications requiring high longitudinal resolutions and/or strong peak intensities.