| 1. |
- Ahmadivand, Arash, et al.
(författare)
-
Toroidal Metaphotonics and Metadevices
- 2020
-
Ingår i: Laser & Photonics reviews. - : WILEY-V C H VERLAG GMBH. - 1863-8880 .- 1863-8899. ; 14:11
-
Forskningsöversikt (refereegranskat)abstract
- Toroidal moments in artificial media have received growing attention and considered as a promising framework for initiating novel approaches to manage intrinsic radiative losses in nanophotonic and plasmonic systems. In the past decade, there has been substantial attention on the characteristics and excitation methods of toroidal multipoles-in particular, toroidal dipole-in 3D bulk and planar metaplatforms. The remarkable advantages of toroidal resonances have thrust the toroidal metasurface technology from relative anonymity into the limelight, in which researchers have recently centered on developing applied optical and optoelectronic subwavelength devices based on toroidal metaphotonics and metaplasmonics. In this focused contribution, the key principles of 3D and flatland toroidal metastructures are described, and the revolutionary tools that have been implemented based on this topology are briefly highlighted. Infrared photodetectors, immunobiosensors, ultraviolet beam sources, waveguides, and functional modulators are some of the fundamental and latest examples of toroidal metadevices that have been introduced and studied experimentally so far. The possibility of the realization of strong plexciton dynamics and pronounced vacuum Rabi oscillations in toroidal plasmonic metasurfaces are also presented in this review. Ultimate efficient extreme-subwavelength scale devices, such as low-threshold lasers and ultrafast switches, are thus in prospect.
|
|
| 2. |
- Andrekson, Peter, 1960, et al.
(författare)
-
Nonlinear optical fiber based high resolution all-optical waveform sampling
- 2007
-
Ingår i: Laser and Photonics Reviews. - : Wiley. - 1863-8899 .- 1863-8880. ; 1:3, s. 231-248
-
Tidskriftsartikel (refereegranskat)abstract
- When there is a need to accurately characterize optical waveforms and, it is not surprising that some of the best, albeit only recently established, techniques to do this rely on all-optical phenomena. Some basic reasons why all-optical sampling holds great promise as a very useful tool well into the foreseeable future are that there are no ringing phenomena with associated waveform distortion as in electronic sampling due to impedance mismatch, and that the time resolution can be made extremely high (
|
|
| 3. |
- Asadchy, V. S., et al.
(författare)
-
Three-dimensional Random Dielectric Colloid Metamaterial with Giant Isotropic Optical Activity
- 2020
-
Ingår i: Laser & Photonics Reviews. - : Wiley. - 1863-8880 .- 1863-8899. ; 14:10
-
Tidskriftsartikel (refereegranskat)abstract
- Motivated by the theoretical observation that isotropic chirality can exist even in completely random systems, a dielectric metamaterial consisting of a random colloid of meta-atoms is designed, which exhibits unprecedentedly high isotropic optical activity. Each meta-atom is composed of a helically arranged cluster of silicon nanospheres. Such clusters can be fabricated by large-scale DNA self-assembly techniques. It is demonstrated that the use of a high concentration of the meta-atoms in the colloid provides significant suppressions of incoherent scattering losses. As a result, the proposed system shows three orders of magnitude improvement of isotropic optical activity as compared with the previous metamaterial designs. This work highlights the significant potential of completely random systems, which are commonly produced in colloidal sciences, for applications as metamaterials toward novel photonic effects and devices.
|
|
| 4. |
- Baranov, Denis, 1990, et al.
(författare)
-
Modifying magnetic dipole spontaneous emission with nanophotonic structures
- 2017
-
Ingår i: Laser and Photonics Reviews. - : Wiley. - 1863-8899 .- 1863-8880. ; 11:3, s. Article Number: 1600268-
-
Forskningsöversikt (refereegranskat)abstract
- Tailoring of electromagnetic spontaneous emission predicted by E. M. Purcell more than 50 years ago has undoubtedly proven to be one of the most important effects in the rich areas of quantum optics and nanophotonics. Although during the past decades the research in this field has been focused on electric dipole emission, the recent progress in nanofabrication and study of magnetic quantum emitters, such as rare-earth ions, has stimulated the investigation of the magnetic side of spontaneous emission. Here, we review the state-of-the-art advances in the field of spontaneous emission enhancement of magnetic dipole quantum emitters with the use of various nanophotonics systems. We provide the general theory describing the Purcell effect of magnetic emitters, overview realizations of specific nanophotonics structures allowing for the enhanced magnetic dipole spontaneous emission, and give an outlook on the challenges in this field, which remain open to future research.
|
|
| 5. |
- Brydegaard, Mikkel, et al.
(författare)
-
Photonic Monitoring of Atmospheric and Aquatic Fauna
- 2018
-
Ingår i: Laser and Photonics Reviews. - : Wiley. - 1863-8880 .- 1863-8899. ; 12:12
-
Tidskriftsartikel (refereegranskat)abstract
- Flying insects are of utmost importance in ecology and for human living conditions. Certain species serve as indispensable pollinators to ensure the availability of food stuffs, while others are dangerous vectors for spreading deadly diseases, such as malaria. Agricultural pests reduce the yield of crops, and their abatement through pesticides cause many additional problems. Birds and bats are frequently carriers of diseases, which, especially for long-distance migrants, cause serious consequences. Clearly, there is high motivation to be able to effectively identify and quantify flying fauna. Here, the emerging field of optics and laser-based monitoring of flying fauna is reviewed with an emphasis on remote sensing based on pulsed and contineous wave (CW) lidar systems, and how they complement existing radar techniques. Furthermore, ground-truth laboratory studies are covered. Wing-beat and overtone spectra as well as reflectance, depolarization and fluorescence properties are studied. The aquatic environment is for many reasons less accessible for optical studies, but is clearly also of great importance. Phytoplankton constitute the start of the aquatic food chain, followed by zooplankton and a long chain of higher animals, including fish, an important part of the human food supply. Finally, how optical monitoring can complement sonar and sampling techniques is discussed.
|
|
| 6. |
- Cai, Fuhong, et al.
(författare)
-
Use of tunable second-harmonic signal from KNbO3 nanoneedles to find optimal wavelength for deep-tissue imaging
- 2014
-
Ingår i: Laser & Photonics reviews. - : Wiley. - 1863-8880 .- 1863-8899. ; 8:6, s. 865-874
-
Tidskriftsartikel (refereegranskat)abstract
- Nonlinear optical (NLO) responses of perovskite-type nanostructures have a variety of potential applications owing to the highly efficient frequency conversion guaranteed by both the material itself and the nanometer-scale configuration. KNbO3 (KN) nanoneedles have been identified as a promising NLO material because of the superior broadband frequency conversion efficiency, and if incident light is propagating in a direction perpendicular to the axis of a nanoneedle, then the phase-matching constraint can be relaxed. Here, the second-harmonic generation (SHG) and third-harmonic generation (THG) responses of both individual and clustered KN nanoneedles are reported. Based on these results, a novel method is proposed for determining the optimal excitation wavelength for NLO imaging of several biological samples, with KN nanoneedles acting as NLO agents. The method is shown to provide the optical features in the focal plane and a more reliable estimation of the optimal excitation wavelength for deep-tissue imaging.
|
|
| 7. |
- Carpenter, J., et al.
(författare)
-
Comparison of principal modes and spatial eigenmodes in multimode optical fibre
- 2017
-
Ingår i: Laser and Photonics Reviews. - : Wiley. - 1863-8899 .- 1863-8880. ; 11:1, s. 1600259-
-
Tidskriftsartikel (refereegranskat)abstract
- Optical waveguide theory is an established part of optical physics. Yet only recently have fundamental phenomena such as spatial eigenmodes and principal modes been demonstrated experimentally. This work leverages recently developed techniques enabling detailed spatiotemporal characterisation of multimode fibre to provide new insights into the fundamentals of fibre propagation. This paper presents detailed analysis of all 420 of a fibre's principal modes and spatial eigenmodes and compares the similarity and differences between these two phenomena. It was found that even over very short lengths, the principal modes can not only significantly suppress modal dispersion but are also a more physically meaningful basis than spatial eigenmodes.
|
|
| 8. |
- Ding, Fei, et al.
(författare)
-
Ultrabroadband strong light absorption based on thin multilayered metamaterials
- 2014
-
Ingår i: Laser & Photonics reviews. - : Wiley. - 1863-8880 .- 1863-8899. ; 8:6, s. 946-953
-
Tidskriftsartikel (refereegranskat)abstract
- Light absorbers have drawn intensive attention as crucial components for solar-energy harvesting, thermal emission tailoring, modulators, etc. However, achievement of light absorbers with wide bandwidth remains a challenge thus far. Here, a thin, unprecedentedly ultrabroadband strong light absorber is proposed and experimentally demonstrated, which consists of periodic taper arrays constructed by an alumina-chrome multilayered metamaterial (MM) on a gold substrate. This MM can change from a hyperbolic material to an anisotropic dielectric material at different frequency ranges and the special material features are the fundamental origins of the ultrabroadband absorption. The absorber is quite insensitive to the incident angle, and can be insensitive to the polarization. One two-dimensional periodic array of 400-nm height MM tapers is fabricated. The measured absorption is over 90% over almost the entire solar spectrum, reaching an average level of 96%, and remains high (above 85%) even in the longer-wavelength range till 4 m. The proposed absorbers open up a new avenue to realize broadband thin light-harvesting structures.
|
|
| 9. |
- Grivas, Christos, et al.
(författare)
-
Generation of Multi-Gigahertz Trains of Phase-Coherent Femtosecond Laser Pulses in Ti:Sapphire Waveguides
- 2018
-
Ingår i: Laser & Photonics reviews. - : WILEY-V C H VERLAG GMBH. - 1863-8880 .- 1863-8899. ; 12:11
-
Tidskriftsartikel (refereegranskat)abstract
- Miniature lasers producing ultrashort phase-coherent pulses at high repetition rates by stable mode-locking in ambient conditions can offer unique capabilities in various applications, spanning from microwave photonics to telecom and biological imaging techniques. Here, the operation of graphene mode-locked lasers based on channel waveguides written by femtosecond and picosecond laser pulses in Ti:sapphire crystals is demonstrated. Trains of pulses of 41.4 fs duration at a 21.25 GHz repetition rate are generated by capitalizing on the formation of solitons in their monolithic resonators through Gires-Tournois interferometers. The latter, allow for effective pulse shaping via tuning of the intracavity group delay dispersion while simultaneously enabling ultralow laser operating thresholds. A number of features of these sources, including their high-brightness and broad bandwidth, are essential ingredients for achieving high longitudinal resolution and sensitivity, which are the primary performance metrics of the Fourier domain/spectral domain variant of optical coherence tomography systems. A further doubling of the laser repetition rate to 42.5GHz is achieved by coherent pulse interleaving in optical fiber technology, thereby underlining the potential of the Ti:sapphire waveguide lasers to produce highly stable, wide-spaced combs of phase-coherent optical frequency lines.
|
|
| 10. |
- Jiang, W., et al.
(författare)
-
Deformable broadband metamaterial absorbers engineered with an analytical spatial Kramers-Kronig permittivity profile
- 2017
-
Ingår i: Laser & Photonics reviews. - : John Wiley & Sons. - 1863-8880 .- 1863-8899. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic (EM) materials with perfect absorption have long been investigated for their important applications in many practical technologies. The trial-and-error method has been mostly employed to achieve this target, either by varying the constituent compositions for traditional natural material absorbers or by running computer simulations for general metamaterial (MM) absorbers. In this work, the authors propose a new method with analytical guidance to build omnidirectional perfect absorbers inspired by the recently proposed spatial Kramers-Kronig (KK) nonreflecting dielectric profile. The subtle combination of the spatial and time dispersions in the metamaterial-engineered KK profile gives the desired broadband response property. More importantly, these features remain invariant when the sample is uniformly compressed or stretched with large thickness change, i.e., this particular broadband absorber is deformable, which has been firstly reported in the literature. The current results will pave a new way to design high-efficiency EM absorbers that could also be extended in general to manipulate waves for other fields or applications. (Figure presented.).
|
|
