A5071414776- Photonic and Optical Devices
- Photonic Crystals and Applications
- Optical Coatings and Gratings
- Semiconductor Lasers and Optical Devices
- Plasmonic and Surface Plasmon Research
- Advanced Fiber Laser Technologies
- Optical Network Technologies
- Fern and Epiphyte Biology
- Orbital Angular Momentum in Optics
- Metamaterials and Metasurfaces Applications
- Silicon Nanostructures and Photoluminescence
- Advanced Photonic Communication Systems
- Advanced Fiber Optic Sensors
- Microfluidic and Bio-sensing Technologies
- Quantum optics and atomic interactions
- Near-Field Optical Microscopy
- Biosensors and Analytical Detection
- Advanced biosensing and bioanalysis techniques
- Mechanical and Optical Resonators
- Advanced Antenna and Metasurface Technologies
- Semiconductor Quantum Structures and Devices
- Advanced Biosensing Techniques and Applications
- Photorefractive and Nonlinear Optics
- Neural Networks and Reservoir Computing
- Molecular Junctions and Nanostructures
University of York
2016-2025
York University
2024
Klinikum Passau
2016-2024
Delft University of Technology
2022
Olgahospital
2020
Sun Yat-sen University
2015-2019
University of Passau
2018-2019
Polytechnic University of Bari
2017
Klinikum Lippe
2007-2017
University of St Andrews
2007-2016
We have designed and fabricated an out-of-plane coupler for butt-coupling from fiber to compact planar waveguides. The is based on a short second-order grating or photonic crystal, etched in waveguide with low-index oxide cladding. optimized using mode expansion-based simulations. Simulations 2-D model show that up 74% coupling efficiency between single-mode 240-nm-thick GaAs-AlO/sub x/ possible. measured 19% test structures.
The physical principles behind the phenomenon of slow light in photonic crystal waveguides, as well their practical limitations, are discussed and put into context. This includes nature propagation, its bandwidth limitation, scaling linear nonlinear interactions with slowdown factor issues such losses, coupling tuning modes. Applications all-optical signal processing appear to be most promising outcome phenomena discussed.
We present a systematic procedure for designing "flat bands" of photonic crystal waveguides slow light propagation. The aims to maximize the group index - bandwidth product by changing position first two rows holes W1 line defect waveguides. A nearly constant is achieved indices 30-90 and as an example, we experimentally demonstrate flat band with 32.5, 44 49 over 14 nm, 11 nm 9.5 around 1550 respectively.
We show the real-space observation of fast and slow pulses propagating inside a photonic crystal waveguide by time-resolved near-field scanning optical microscopy. Local phase group velocities modes are measured. For specific frequency we observe localized pattern associated with flat band in dispersion diagram. During at least 3 ps, movement this field is hardly discernible: its velocity would be most c/1000. The huge trapping times without use cavity reveal new perspectives for time...
We present high-efficiency grating couplers for coupling between a single-mode fiber and nanophotonic waveguides, fabricated both in silicon-on-insulator (SOI) InP membranes using BenzoCycloButene wafer bonding. The efficiency is substantially increased by adding gold bottom mirror to the structures. measured 69% SOI 56% bonded membrane
We fabricated slotted photonic crystal waveguides and cavities supporting resonant modes in air. Their peculiar geometry enables the detection of refractive index changes a given analyte with high sensitivity because large overlap between optical mode analyte. This yields figure merit for device we are able to report values S=Δλ/Δn over 1500. By applying heterostructure geometry, create quality-factor essential realizing low limits up Q=50 000.
The authors show that light scattering from high-Q planar photonic crystal nanocavities can display Fano-like resonances corresponding to the excitation of localized cavity modes. By changing conditions, we are able tune observed lineshapes strongly asymmetric and dispersivelike symmetric Lorentzians. Results interpreted according Fano model quantum interference between two coupled channels. Combined measurements line shape analysis on a series silicon L3 as function nearby hole displacement...
The non-deterministic nature of photon sources is a key limitation for single-photon quantum processors. Spatial multiplexing overcomes this by enhancing the heralded yield without output noise. Here intrinsic statistical limit an individual source surpassed spatially two monolithic silicon-based correlated pair in telecommunications band, demonstrating 62.4% increase unwanted multipair generation. We further demonstrate scalability scheme photons generated waveguides pumped via integrated...
Subwavelength imaging requires the use of high numerical aperture (NA) lenses together with immersion liquids in order to achieve highest possible resolution. Following exciting recent developments metasurfaces that have achieved efficient focusing and novel beam-shaping, race is on demonstrate ultrahigh-NA metalenses. The NA has been demonstrated so far = 1.1, a TiO2 metalens back-immersion. Here, we introduce transmission visible range, based crystalline silicon (c-Si). higher refractive...
Temporal optical solitons have been the subject of intense research due to their intriguing physics and applications in ultrafast optics supercontinuum generation. Conventional bright result from interaction anomalous group-velocity dispersion self-phase modulation. Here we report discovery an entirely new class arising purely negative fourth-order modulation, which can occur even for normal dispersion. We provide experimental numerical evidence shape-preserving propagation flat temporal...
This review provides an insight into the recent developments of photonic crystal (PhC)-based devices for sensing and imaging, with a particular emphasis on biosensors. We focus two main classes devices, namely sensors based PhC cavities those guided mode resonances (GMRs). distinction is able to capture richness possibilities that PhCs are offer in this space. present examples highlighting applications where can new capabilities, open up or enable improved performance, clear different types...
Metalenses consist of nanostructures that locally control the optical phase. They offer many degrees freedom for manipulating a wavefront, which gives number advantages over bulk lenses, such as straightforward elimination spherical aberrations and an ultrathin dimension. Here, we compare phase profiles metalenses made different dielectric materials note advantage high refractive index materials. Higher silicon afford more in terms design fabrication are basis high-performance metalenses,...
Metalenses are nanostructured surfaces that mimic the functionality of optical elements. Many exciting demonstrations have already been made, for example, focusing into diffraction-limited spots or achromatic operation over a wide wavelength range. The key is yet missing, however, and most important applications such as smartphones virtual reality, ability to perform imaging function with single element field view. Here, by relaxing constraint on resolution, we demonstrate single-layer...
Dielectric metasurfaces support resonances that are widely explored both for far-field wavefront shaping and near-field sensing imaging. Their design explores the interplay between localised extended resonances, with a typical trade-off Q-factor light localisation; high Q-factors desirable refractive index while localisation is imaging resolution. Here, we show dielectric metasurface consisting of nanohole array in amorphous silicon provides favourable these requirements. We have designed...
Here we present a roadmap on Photonic metasurfaces. This document consists of number perspective articles different applications, challenge areas or technologies underlying photonic Each will introduce the topic, state art as well give an insight into future direction subfield.
We describe a promising thin-slab light-emitting diode (LED) design, which uses highly efficient coherent external scattering of trapped light by two-dimensional (2D) photonic crystal. The generation region was an unpatterned heterostructure surrounded the extraction region, thin film patterned as 2D A six-fold photoluminescence enhancement observed compared to LED. That corresponded 70% quantum efficiency.
Electromagnetic band structure can produce either an enhancement or a suppression of spontaneous emission from two-dimensional (2-D) photonic crystal thin films. We believe that such effects might be important for light emitting diodes. Our experiments were based on thin-film InGaAs-InP 2-D crystals at ambient temperature, but the concepts would apply equally to InGaN films, example. show magnitude Purcell factor, F/sub p//spl sim/2, spatially extended modes, is similar tiny mode in three...
We report nonlinear measurements on 80microm silicon photonic crystal waveguides that are designed to support dispersionless slow light with group velocities between c/20 and c/50. By launching picoseconds pulses into the comparing their output spectral signatures, we show how self phase modulation induced broadening is enhanced due light. Comparison of numerical simulations pulse propagation elucidates contribution various effects determine shape waveguide transfer function. In particular,...
The confinement and controlled movement of metal nanoparticles nanorods is an emergent area within optical micromanipulation. In this letter we experimentally realise a novel trapping geometry near the plasmon resonance using annular light field possessing helical phasefront that confines nanoparticle to vortex core (dark) region. We interpret our data with theoretical framework based upon Maxwell stress tensor formulation elucidate total forces nanometric particles particle resonance....