Ivan Avrutsky

Reflection of a Beam of Finite Size from a Corrugated Waveguide

Abstract The paper is concerned with the influence of the finite size of an incident beam upon both the anomalous-reflection spectrum and the shape of the energy distribution in a reflected beam. It is proved experimentally that the use of corrugated waveguides as a laser-resonator selective mirror improves the spatial coherence of radiation.

Nonlocal effects in effective-medium response of nanolayered metamaterials

We demonstrate that the majority pf plasmonic nanolayered composites, despite being subwanelength, are not described by effective medium theory and develop an adequate description of electromagnetism in these systems.

Sub-wavelength plasmonic modes in a conductor-gap-dielectric system with a nanoscale gap

We study guided modes in a conductor-gap-dielectric (CGD) system that includes a low-index dielectric gap layer of deep sub-wavelength thickness sandwiched between a conductor and a high-index dielectric cladding. Analysis of the dispersion equation for CGD modes provides an analytical estimation for the cut-off thickness of the gap layer. This guided mode is unusual because it exists when the gap thickness is less than the cutoff thickness. In the direction normal to the interfaces, the modal electric field is tightly confined within the gap. Sub-wavelength lateral mode confinement is readily provided by a spatial variation of the gap-layer thickness: the modal field localizes at the narrowest gap. Various lateral confinement schemes are proposed and verified by numerical simulations. Possible applications of CGD modes include surface-plasmon nano-lasers (SPASERs) and sensors. If these plasmonic waveguides are scaled for operation at far infrared rather than telecomm wavelengths, then the propagation losses are dramatically reduced, thereby enabling the construction of practical chip-scale plasmonic integrated circuits or PLICs.

Highly confined optical modes in nanoscale metal-dielectric multilayers

We show that a stack of metal-dielectric nanolayers, in addition to the long- and short-range plasmon polaritons, guides also an entire family of modes strongly confined within the multilayer—the bulk plasmon polariton modes. We propose a classification scheme that reflects specific properties of these modes. We report experimental verification of the bulk modes by measuring modal indices in a structure made of three pairs of silica 29 nm/gold 25 nm layers. DOI: 10.1103/PhysRevB.75.241402 PACS numbers: 73.20.Mf, 42.25.Bs, 42.82.Et, 73.21.Ac Nanoscale confinement of light is of great interest for applications in sensing, imaging, all-optical signal processing, and computing. Subwavelength confinement attributed to gap plasmon polaritons GPPs has been demonstrated in a thin dielectric layer surrounded by metallic claddings. 1 Here we present another solution to subdiffraction confinement of light and show that a stack of metal-dielectric nanolayers guides a family of modes strongly confined within the multilayer—the bulk plasmon polariton BPP modes. The bulk modes have very short penetration depth into the claddings even if the claddings are made of dielectric materials. Their modal indices ratio of the light velocity in vacuum to the phase velocity of a guided mode are typically large in absolute value and may be both positive and negative. 2 We propose a classification scheme that reflects specific properties of BPPs. We verify BPPs experimentally by measuring their modal indices in a structure made of three pairs of silica-gold nanolayers. When considering light confinement in a waveguide, the

Surface-plasmon-assisted resonant tunneling of light through a periodically corrugated thin metal film

We present experimental results and a numerical model confirming that surface plasmons can resonantly enhance light transmission through a corrugated metal film. A new interpretation in terms of plasmon-assisted light tunneling is given to recent experiments on light penetration through periodic subwavelength holes in a thin metal film. We designed a narrow-band filter suitable for applications in optical communication by optimizing the film and the grating parameters.

Optical properties of Al2O3 thin films grown by atomic layer deposition

We employed the atomic layer deposition technique to grow Al(2)O(3) films with nominal thicknesses of 400, 300, and 200 nm on silicon and soda lime glass substrates. The optical properties of the films were investigated by measuring reflection spectra in the 400-1800 nm wavelength range, followed by numerical fitting assuming the Sellmeier formula for the refractive index of Al(2)O(3). The films grown on glass substrates possess higher refractive indices as compared to the films on silicon. Optical waveguiding is demonstrated, confirming the feasibility of high-index contrast planar waveguides fabricated by atomic layer deposition.

High-efficiency single-order waveguide grating coupler.

High-efficiency single-order grating coupling between an optical waveguided mode and a volume wave is achieved by means of a double-sided corrugated cover film that has phase-shifted undulations. A greater than 90% outcoupling ratio into air is demonstrated for weakly guiding ion-exchanged waveguides. The conditions for efficient coupling and the tolerances on them are established.

Design of widely tunable semiconductor lasers and the concept of binary superimposed gratings (BSG's)

We propose a new concept of binary superimposed gratings (BSGs) as multiwavelength grating reflectors and show it as an effective structural improvement over the existing designs, to both the fabrication process and device performance. We also present a study of key design issues for widely tunable lasers based on grating mirrors with a comb-like reflection spectrum and summarize simple design rules for the grating part of the laser, based on analytical and numerical analysis. The binary supergrating consists of elements of equal size whose refractive index is allowed to be one of two possible values, which are sequenced according to a binary optics formalism to effect a spatial superposition of multiple sets of single-frequency gratings, and its implementation is well within the standard e-beam lithography limits. The calculations of lasing frequency, mode, and side-mode suppression ratio of the tunable laser are formulated and presented along with numerical examples.

A simple miniature optical spectrometer with a planar waveguide grating coupler in combination with a plano-convex lens

A miniature optical spectrometer with a thin-film planar waveguide grating coupler in combination with a miniature plano-convex focusing lens has been investigated. With optical part of the spectrometer as small as 0.2 cubic cm, the spectral resolution varies from 0.3 nm to 4.6 nm within the wavelength range 488.0 nm - 632.8 nm.

Interference Phenomena in Waveguides with Two Corrugated Boundaries

Abstract Waveguide structures with two corrugated interfaces are considered. It is shown theoretically and experimentally that these structures can form the basis for a highly-efficient unidirectional grating coupler for slab waveguides. The anomalous light reflection from waveguides with two corrugated boundaries is also considered. The possibility of using corrugated waveguides for frequency stabilization of a semiconductor laser is demonstrated.