| 1. |
- Benisty, H., et al.
(författare)
-
Low-loss photonic-crystal and monolithic InP integration : Bands, bends, lasers, filters
- 2004
-
Ingår i: Photonic Crystal Materials and Devices II. - : SPIE - International Society for Optical Engineering. - 0819452688 ; , s. 119-128
-
Konferensbidrag (refereegranskat)abstract
- Practical realizations of 2D (planar) photonics crystal (PhC) are either on a membrane or etched through a conventional heterostructure. While fascinating objects can emerge from the first approach, only the latter approach lends itself to a progressive integration of more compact PhC's towards monolithic PICs based on InP. We describe in this talk the various aspects from technology to functions and devices, as emerged from the European collaboration "PCIC". The main technology tour de force is deep-etching with aspect ratio of about 10 and vertical sidewall, achieved by three techniques (CAIBE, ICP-RIE, ECR-RIE). The basic functions explored are bends, splitters/combiners, mirrors, tapers, and the devices are filters and lasers. At the end of the talk, I will emphasize some positive aspects of "broad" multimode PhC waveguides, in view of compact add-drop filtering action, notably.
|
|
| 2. |
- Benisty, H., et al.
(författare)
-
Models and measurements for the transmission of submicron-width waveguide bends defined in two-dimensional photonic crystals
- 2002
-
Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 38:7, s. 770-785
-
Tidskriftsartikel (refereegranskat)abstract
- One of the essential building-blocks of miniature photonic crystal (PC)-based photonic integrated circuits (PICs) is the sharp bend. Our group has focused on the 2-D photonic crystal based on a triangular lattice of holes perforating a standard heterostructure. The latter, GaAlAs-based or InP-based, is vertically a monomode waveguide. We consider essentially one or two 60 bends defined by one to five missing rows, spanning both cases of monomode and multimode channel waveguides. From intensive modeling and various experimental measurements (both on GaAs and InP), we point out the origin of the present level of bend insertion losses and discuss the merits of the many roads open for improved design.
|
|
| 3. |
- Talneau, A., et al.
(författare)
-
Modal behavior of single-line photonic crystal guiding structures on InP substrate
- 2004
-
Ingår i: Photonics and Nanostructures - Fundamentals and Applications. - : Elsevier BV. - 1569-4410 .- 1569-4429. ; 2:1, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- We have experimentally investigated the modal behaviour and the polarization dependence of the transmission through single-missing-row photonic crystal (PC) straight guides, bends and combiners, fabricated on InP substrate. A photonic crystal-based taper has been included to funnel light in these strongly confined structures. Two-dimensional finite-difference time-domain simulations have been performed and favorably compared with the measurements. It is found that the scattering process occurring at a bend/combiner transition plays a key role on the overall transmission.
|
|
| 4. |
- Talneau, A., et al.
(författare)
-
High-bandwidth transmission of an efficient photonic-crystal mode converter
- 2004
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 29:15, s. 1745-1747
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated both theoretically and experimentally the spectral behavior and the transmission and reflection performance of a photonic-crystal (PhC) mode converter upon an InP substrate. This taper exhibits 70% transmission efficiency on an 80-nm bandwidth when it couples a ridge access guide to a strongly confined single-missing-row PhC guide. Such a taper design included in a PhC bend contributes a large benefit to the overall transmission budget of the PhC-based link.
|
|
| 5. |
- Zhang, P., et al.
(författare)
-
Numerical investigation of the flat band Bloch modes in a 2D photonic crystal with Dirac cones
- 2015
-
Ingår i: Optics Express. - : The Optical Society. - 1094-4087 .- 1094-4087. ; 23:8, s. 10444-10452
-
Tidskriftsartikel (refereegranskat)abstract
- A numerical method combining complex-k band calculations and absorbing boundary conditions for Bloch waves is presented. We use this method to study photonic crystals with Dirac cones. We demonstrate that the photonic crystal behaves as a zero-index medium when excited at normal incidence, but that the zero-index behavior is lost at oblique incidence due to excitation of modes on the flat band. We also investigate the formation of monomodal and multimodal cavity resonances inside the photonic crystals, and the physical origins of their different line-shape features.
|
|
| 6. |
- Dastmalchi, B., et al.
(författare)
-
A New Perspective on Plasmonics: Confinement and Propagation Length of Surface Plasmons for Different Materials and Geometries
- 2016
-
Ingår i: Advanced Optical Materials. - : Wiley. - 2195-1071. ; 4:1, s. 177-184
-
Tidskriftsartikel (refereegranskat)abstract
- Surface-plasmon polaritons are electromagnetic waves propagating on the surface of a metal. Thanks to subwavelength confinement, they can concentrate optical energy on the micrometer or even nanometer scale, enabling new applications in bio-sensing, optical interconnects, and nonlinear optics, where small footprint and strong field concentration are essential. The major obstacle in developing plasmonic applications is dissipative loss, which limits the propagation length of surface plasmons and broadens the bandwidth of surface-plasmon resonances. Here, a new analysis of plasmonic materials and geometries is presented which fully considers the tradeoff between propagation length and degree of confinement. It is based on a two-dimensional analysis of two independent figures of merit and the analysis is applied to relevant plasmonic materials, e.g., noble metals, aluminum, silicon carbide, doped semiconductors, graphene, etc. The analysis provides guidance on how to improve the performance of any particular plasmonic application and substantially eases the selection of the plasmonic material.
|
|
| 7. |
- Dastmalchi, B., et al.
(författare)
-
Strong group-velocity dispersion compensation with phase-engineered sheet metamaterials
- 2014
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 89:11, s. Article no. 115123-
-
Tidskriftsartikel (refereegranskat)abstract
- Resonant metamaterials usually exhibit substantial dispersion, which is considered a shortcoming for many applications. Here we take advantage of the ability to tailor the dispersive response of a metamaterial, introducing a new method of group-velocity dispersion compensation in telecommunication systems. The method consists of stacking a number of highly dispersive sheet metamaterials and is capable of compensating the dispersion of optical fibers with either negative or positive group-velocity dispersion coefficients. We demonstrate that the phase-engineered metamaterial can provide strong group-velocity dispersion management without being adversely affected by large transmission loss, while at the same time offering high customizability and a small footprint.
|
|
| 8. |
- Ginis, V., et al.
(författare)
-
Broadband metasurfaces enabling arbitrarily large delay-bandwidth products
- 2016
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 108:3
-
Tidskriftsartikel (refereegranskat)abstract
- Metasurfaces allow for advanced manipulation of optical signals by imposing phase discontinuities across flat interfaces. Unfortunately, these phase shifts remain restricted to values between 0 and 2 pi, limiting the delay-bandwidth product of such sheets. Here, we develop an analytical tool to design metasurfaces that mimic three-dimensional materials of arbitrary thickness. In this way, we demonstrate how large phase discontinuities can be realized by combining several subwavelength Lorentzian resonances in the unit cell of the surface. Our methods open up the temporal response of metasurfaces and may lead to the construction of metasurfaces with a plethora of new optical functions.
|
|
| 9. |
- Ginis, V., et al.
(författare)
-
Metamaterials enhancing optical forces
- 2014
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781628410730 ; 9125
-
Konferensbidrag (refereegranskat)abstract
- The interaction between light and matter involves not only an energy transfer, but also the transfer of linear momentum. In everyday life applications this linear momentum of light is too small to play any significant role. However, in nanoscale dimensions, the associated optical forces start to play an increasingly important role. These forces are, e.g., large enough for exiting experiments in the fields of cavity-optomechanics, laser cooling and optical trapping of small particles. Recently, it has been suggested that optical gradient forces can also be employed for all-optical actuation in micro- and nanophotonic systems. The typical setup consists of two slab waveguides positioned in each others vicinity such that they are coupled through the interaction of the evanescent tails. Although the gradient forces between these waveguides can be enhanced considerably using electromagnetic resonators or slow-light techniques, the resulting displacements remain relatively small. In this contribution, we present an alternative approach to enhance optical gradient forces between waveguides using a combination of transformation optics and metamaterials. Our design starts from the observation that gradient forces exponentially decay with the separation distance between the waveguides. Therefore, we employ transformation optics to annihilate the apparent distance for light between the waveguides. Analytical calculations confirm that the resulting forces indeed increase when such an annihilating cladding is inserted. Subsequently, we discuss the metamaterial implementation of this annihilating medium. Such lensing media automatically translate into anisotropic metamaterials with negative components in the permittivity and permeability tensors. Our full-wave numerical simulations show that the overall amplification is highly limited by the loss-tangent of the metamaterial cladding. However, as this cladding only needs to operate in the near-field for a specific polarization, we can also consider single-negative metamaterial implementations. We finally demonstrate that in this way metamaterials can support optical forces enhanced by more than 200 times [Phys. Rev. Lett. 110, 057401 (2013)].
|
|
| 10. |
|
|
