A5102008381- Photonic and Optical Devices
- Photonic Crystals and Applications
- Advanced Fiber Laser Technologies
- Advanced Fiber Optic Sensors
- Semiconductor Lasers and Optical Devices
- Optical Network Technologies
- Orbital Angular Momentum in Optics
- Optical Coatings and Gratings
- Mechanical and Optical Resonators
- Photorefractive and Nonlinear Optics
- Atomic and Molecular Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Photonic Crystal and Fiber Optics
- Advanced MEMS and NEMS Technologies
- Near-Field Optical Microscopy
- Laser-induced spectroscopy and plasma
- Advanced Photonic Communication Systems
- Quantum and Classical Electrodynamics
- Laser-Plasma Interactions and Diagnostics
- Atomic and Subatomic Physics Research
- Crystallization and Solubility Studies
- Plasmonic and Surface Plasmon Research
- Quantum Information and Cryptography
- Surface Chemistry and Catalysis
- X-ray Diffraction in Crystallography
Copenhagen University Hospital
2024
University of Copenhagen
2023-2024
Mental Health Services
2024
Aarhus University
1992-2014
Technical University of Denmark
1998-2006
Netherlands Institute for Radio Astronomy
2006
Leiden University
1994-2005
Aalborg University
2000-2001
Huygens Institute for History and Culture of the Netherlands
1994
Max Planck Institute for Nuclear Physics
1990
We demonstrate a memory for light based on optomechanically induced transparency. achieve long storage time by leveraging the ultralow dissipation of soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we lifetime ${T}_{1}\ensuremath{\approx}23\text{ }\text{ }\mathrm{ms}$ and retrieval efficiency $\ensuremath{\eta}\ensuremath{\approx}40%$ classical coherent pulses. anticipate quantum to be possible moderate cryogenic conditions...
The first successful laser cooling of ions at relativistic energies was observed the Heidelberg TSR storage ring. A $^{7}\mathrm{Li}^{+}$-ion beam 13.3 MeV oberlapped with resonant copropagating and counterpropagating beams. metastable were cooled from 260 K to a longitudinal temperature below 3 decelerated by several keV. velocity distribution determined fluorescence method. After strongly enhanced narrow peak appeared in Schottky noise spectrum addition uncooled ion distribution.
Topology optimization has been used to design a 60 degrees bend in single-mode planar photonic crystal waveguide. The realized silicon-on-insulator material and we demonstrate record-breaking 200-nm transmission bandwidth with an average loss of 0.43+/-0.27 dB for the TE polarization. experimental results agree well 3D finite-difference-time-domain simulations.
The interaction of laser-induced and intrabeam forces has been studied in a dense stored beam 100-keV $^{7}\mathrm{Li}^{+}$ ions. A fraction the ions (\ensuremath{\sim}${10}^{\mathrm{\ensuremath{-}}4}$) exist metastable 1s2s $^{3}$S state. Using this state as laser spectroscopic probe, we observe fast longitudinal heating injected, nonequilibrium distribution due to Coulomb scattering. Laser cooling is ineffective during period. equilibrated subsequently cooled temperature \ensuremath{\sim}1...
We have investigated the properties of TM polarized light in planar photonic crystal waveguide structures, which exhibit band gaps for TE light.Straight and bent waveguides couplers been fabricated silicon-on-insulator material modelled using a 3D finite-difference-time-domain method.The simulated spectra are excellent agreement with experimental results, show propagation loss as low 2.5±4 dB/mm around 1525 nm bend losses at 2.9±0.2dB light.We demonstrate high coupling simple coupler size ~...
We report the first measurement of photon angular momentum inside a dielectric medium. In contrast to corresponding linear momentum, which is proportional refractive index n, we find be independent n.
Several planar photonic crystal components topology-optimized for TE-polarized light, including 60 masculine bends, Y-splitters, and 90 have been characterized the TM polarization. The experimental results are confirmed by finite-difference time-domain calculations. surprising efficiency TM-polarized light is found paves way suitable both polarizations.
A scanning near-field optical microscope is used to directly map the propagation of light in wavelength range 1500--1630 nm along straight photonic crystal waveguides (PCWs) fabricated on silicon-on-insulator wafers. The PCWs were formed by removing a single row holes triangular 428-nm-period lattices with different filling factors (0.76 and 0.82) connected access ridge waveguides. Using images we investigate for TM TE polarizations (the electric field perpendicular/parallel sample surface)....
An optical fiber sensor based on long-period gratings (LPG) for selective measurements of flap- and edge-wise bending a wind turbine blade is presented. Two consecutive LPGs separated by 40 mm interfere to improve resolution reduce noise in D-shaped fiber. The mode profile the device was characterized experimentally provide model describing couplings. tested blade.
The impact of ice 1h formation inside the holes a photonic crystal fiber Bragg grating was analyzed and discussed. As result ice's expansion, broadening spectrum observed that corresponds to internal microbending after some temperature cycling leads failure fiber. An analytical model with which estimate compression forces is proposed, calculated values are found be in agreement reported data.
Numerical and experimental studies on the photonic crystal waveguide intersection based topology optimisation design method are reported effectiveness of this technique is shown by achieving high transmittance spectra with low crosstalk for straightforward beam-propagation line in intersection.
Protein detection using a photonic crystal waveguide-based biosensor is presented two different sensing features for the device - bandgap-edge, common-known feature, and novel feature arising due to polarization mixing.
We present an optical fiber bend sensor with enhanced resolution based on the principle of a Mach-Zehnder interferometer in transmission. The is two identical Long-Period Gratings separated by approximately 100 mm D-shaped single-mode fiber. provides narrow resonance bandwidth compared to typical from Grating. was recoated low refractive index polyimide and embedded fiber-glass base plate before it characterized as bending sensor.
We thermally regenerated long-period fiber gratings at 850°C. Two strong seed 10cm apart interfere near 1550nm. The grating has narrow interference fringes above 20% deep and stable up to 1000°C ideal for high-temperature sensors.
We demonstrate the utilization of a blade load sensor system based on two identical Long-Period Gratings in Mach-Zehnder configuration. The experimental results potential Grating interrogation system.
We report the design, fabrication and characterization of a photonic crystal directional coupler with size ∼20×20 μm 2 fabricated in silicon-on-insulator material. Using scanning near-field optical microscope we demonstrate high coupling efficiency for TM polarized light at telecom wavelengths. By comparing images recorded after area, features distribution are analyzed. Finally, observations found to be agreement transmission measurements conducted same sample.
We have realized phase encoding and sensing of signals for quantum cryptography in compact circuits made with standard silica-on-silicon technology. The include Bragg grating filters allowing multichannel dense channel spacing, they are thermally balanced to avoid crosstalk.
Topological insulators were originally discovered for electron waves in condensed matter systems. Recently this concept has been transferred to bosonic systems such as photons and phonons, which propagate materials patterned with artificial lattices that emulate spin-Hall physics. This work motivated, part, by the prospect of topologically protected transport along edge channels on-chip circuits. Importantly, even principle, topology protects propagation against backscattering, but not loss,...
ABSTRACT The use of activated sludge models (ASMs) is a common way in the field wastewater engineering terms plant design, development, optimization, and testing stand-alone treatment plants. focus this study was development joint control system (JCS) for municipal (mWWTP) an upstream industrial (iWWTP) to create synergies saving aeration energy. Therefore, ASM3 + BioP model mWWTP developed test different scenarios find best set-points novel JCS. A predictive equation total nitrogen load...
Faithful quantum state transfer between telecom photons and microwave frequency mechanical oscillations necessitate a fast conversion rate low thermal noise. Two-dimensional (2D) optomechanical crystals (OMCs) are favorable candidates that satisfy those requirements. 2D OMCs enable sufficiently high (1∼10 GHz) to make the resolved-sideband regime achievable, prerequisite for many protocols. It also supports higher conductance than 1D structures, mitigating parasitic laser absorption heating....