Mie-driven directional nanocoupler for Bloch surface wave photonic platform

Modern integrated photonic platforms should combine low-loss guiding, spectral flexibility, high light confinement, and close packing of optical components. One of the prominent platforms represents a one-dimensional photonic crystal combined with dielectric nanostructures that manipulate low-loss Bloch surface waves (BSWs). Proper design of nanostructures gives rise to a variety of optical resonances suitable for efficient capturing and controlling light. In this work, we achieve color-selective directional excitation of BSWs mediated by Mie resonances in a semiconductor nanoparticle. We show that a single silicon nanoparticle can be used as a subwavelength multiplexer switching the BSW excitation direction from forward to backward within the 30 nm spectral range with its central wavelength governed by the nanoparticle size. Our work opens a route for the on-demand fabrication of photonic nanocouplers with tailored optical properties and submicron footprint

Enhanced Nonlinear Light Generation in Oligomers of Silicon Nanoparticles under Vector Beam Illumination

All-dielectric nanoparticle oligomers have recently emerged as promising candidates for nonlinear optical applications. Their highly resonant collective modes, however, are difficult to access by linearly polarized beams due to symmetry restraints. In this paper, we propose a new way to increase the efficiency of nonlinear processes in all-dielectric oligomers by tightly focused azimuthally polarized cylindrical vector beam illumination. We demonstrate two orders enhancement of the third-harmonic generation signal, governed by a collective optical mode represented by out-of-plane magnetic dipoles. Crucially, the collective mode is characterized by strong electromagnetic field localization in the bulk of the nonlinear material. For comparison, we measure third-harmonic generation in the same oligomer pumped with linearly and radially polarized fundamental beams, which both show significantly lower harmonic output. We also provide numerical analysis to describe and characterize the observed effect. Our findings open a new route to enhance and modulate the third-harmonic generation efficiency of Mie-resonant isolated nanostructures by tailoring the polarization of the pump beam.This work was performed in part at the Cornell NanoScale Facility, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which was supported by the National Science Foundation (Grant ECCS-1542081). The work was performed under financial support of the Russian Ministry of Education and Science (Grant No. 14.W03.31.0008, development of the nonlinear microscopy setup), MSU Quantum Technology Center and Foundation for the Advancement of Theoretical Physics and Mathematics “BASIS” 19-2-6-155-1 (numerical results), and the Russian Foundation for Basic Research (18-02-00880 and 19-32-90218 third-harmonic microscopy experiments). D.A.S. acknowledges funding from the Australian Research Council Early Career Researcher Award (DE190100430) and the Russian Foundation for Basic Research (Grant Nos. 18-02-00381 and 19-02-00261). I.I.V. acknowledges partial support by the Foundation for the Advancement of Theoretical Physics and Mathematics “Basis”. G.S. and M.R.S. acknowledge support by the Cornell Center for Materials Research with funding from the NSF MRSEC program (DMR-1719875) and Office of Naval Research (ONR) under Grant no. N00014-17-1-2161

Mie resonant diamond nanoantennas for spontaneous light emission

The size of the hosting particle affects the spontaneous light emission of embedded emitters. Here we study submicron-sized diamond particles containing silicon-vacancy color centers. We measure size-dependent scattering spectra, fluorescence emission rate, and Raman scattering intensity. Obtained results are found to agree with our calculations and demonstrate the potential of Mie resonances in nanoantennas design

Single-walled carbon nanotube membranes as non-reflective substrates for nanophotonic applications

We demonstrate that single-walled carbon nanotube (SWCNT) membranes can be successfully utilized as nanometer-thick substrates for enhanced visualization and facilitated study of individual nanoparticles. As model objects, we transfer optically resonant 200 nm silicon nanoparticles onto pristine and ethanol-densified SWCNT membranes by the femtosecond laser printing method. We image nanoparticles by scanning electron and bright-field optical microscopy, and characterize by linear and Raman scattering spectroscopy. The use of a pristine SWCNT membrane allows to achieve an order-of-magnitude enhancement of the optical contrast of the nanoparticle bright field image over the results shown in the case of the glass substrate use. The observed optical contrast enhancement is in agreement with the spectrophotometric measurements showing an extremely low specular reflectance of the pristine membrane (≤0.1%). Owing to the high transparency, negligibly small reflectance and thickness, SWCNT membranes offer a variety ofperspective applications in nanophotonics, bioimaging and synchrotron radiation studies.Peer reviewe

Optical Magnetism and Fundamental Modes of Nanodiamonds

The optical properties of color centers in nanodiamonds are widely used in various branches of photonics and interdisciplinary studies. Here, we report on an experimental study of the fundamental eigenmodes of subwavelength diamond nanoparticles. The eigenmodes reveal themselves as scattering resonances, which were measured by single-particle dark-field spectroscopy and calculated both numerically and analytically. The resonances experience a red-shift with increasing particle size, and in the case of an anisotropic particle, they change depending on the polarization of the input light. As an example of an application, the Purcell enhancement of the dipole emission from such nanodiamonds is numerically demonstrated. This study demonstrates a simple way to improve the efficiency of diamond-based sensors and single-photon sources by choosing nanoparticles of optimal size and shape

Laser printing of spherical silicon nanoparticles for in-plane color routing

Femtosecond laser printing allows the creation of spherical nanoparticles on a wide range of substrates. Here we apply this technique to fabricate Mie-resonant color-routing nanoantennas. First, we place single silicon particles on a dielectric multilayer and demonstrate color-selective directional excitation of Bloch surface waves. Second, we create asymmetric dimers of silicon nanospheres that provide color-selective directional scattering of evanescent waves. Our results highlight the potential of laser printing as an advanced fabrication technique for integrated optics