10 research outputs found
Hur lär barn om väder?
Jag har velat ta reda på hur det är att arbeta med det naturvetenskapliga ämnet väder med
åttaåringar. Mina utgångspunkter har varit teorier om lärande, experimentets roll för lärande
och lärarens roll för lärandet. Den tematiska arbetsformen har bildat ramen för undersökning
om hur barn lär om väder.
Jag har intervjuat eleverna i smågrupper och det har kommit fram intressanta reflektioner från
eleverna. Eleverna har uttryckt att de har lärt sig nya saker om väder. De har också uttryckt att
gamla föreställningar har förändrats. Det finns en utbredd rädsla och forskningen är eftersatt
kring barns lärande om naturvetenskap. Jag har i min undersökning upplevt att åttaåringar kan
förstå komplexa väderfenomen, med hjälp av olika pedagogiska inlärningsstilar
Media 2: Porous silicon integrated Mach-Zehnder interferometer waveguide for biological and chemical sensing
Originally published in Optics Express on 26 August 2013 (oe-21-17-19488
Media 1: Terahertz nonlinear conduction and absorption saturation in silicon waveguides
Originally published in Optica on 20 June 2015 (optica-2-6-553
Media 3: Terahertz surface plasmon polaritons on a semiconductor surface structured with periodic V-grooves
Originally published in Optics Express on 25 March 2013 (oe-21-6-7041
Media 1: Terahertz surface plasmon polaritons on a semiconductor surface structured with periodic V-grooves
Originally published in Optics Express on 25 March 2013 (oe-21-6-7041
Media 4: Terahertz surface plasmon polaritons on a semiconductor surface structured with periodic V-grooves
Originally published in Optics Express on 25 March 2013 (oe-21-6-7041
Media 2: Terahertz surface plasmon polaritons on a semiconductor surface structured with periodic V-grooves
Originally published in Optics Express on 25 March 2013 (oe-21-6-7041
Nonlinear Terahertz Absorption of Graphene Plasmons
Subwavelength
graphene structures support localized plasmonic resonances in the
terahertz and mid-infrared spectral regimes. The strong field confinement
at the resonant frequency is predicted to significantly enhance the
light-graphene interaction, which could enable nonlinear optics at
low intensity in atomically thin, subwavelength devices. To date,
the nonlinear response of graphene plasmons and their energy loss
dynamics have not been experimentally studied. We measure and theoretically
model the terahertz nonlinear response and energy relaxation dynamics
of plasmons in graphene nanoribbons. We employ a terahertz pump–terahertz
probe technique at the plasmon frequency and observe a strong saturation
of plasmon absorption followed by a 10 ps relaxation time. The observed
nonlinearity is enhanced by 2 orders of magnitude compared to unpatterned
graphene with no plasmon resonance. We further present a thermal model
for the nonlinear plasmonic absorption that supports the experimental
results. The model shows that the observed strong linearity is caused
by an unexpected red shift of plasmon resonance together with a broadening
and weakening of the resonance caused by the transient increase in
electron temperature. The model further predicts that even greater
resonant enhancement of the nonlinear response can be expected in
high-mobility graphene, suggesting that nonlinear graphene plasmonic
devices could be promising candidates for nonlinear optical processing
Plasmon-Enhanced Terahertz Photodetection in Graphene
We report a large area terahertz
detector utilizing a tunable plasmonic resonance in subwavelength
graphene microribbons on SiC(0001) to increase the absorption efficiency.
By tailoring the orientation of the graphene ribbons with respect
to an array of subwavelength bimetallic electrodes, we achieve a condition
in which the plasmonic mode can be efficiently excited by an incident
wave polarized perpendicular to the electrode array, while the resulting
photothermal voltage can be observed between the outermost electrodes
Plasmon-Enhanced Terahertz Photodetection in Graphene
We report a large area terahertz
detector utilizing a tunable plasmonic resonance in subwavelength
graphene microribbons on SiC(0001) to increase the absorption efficiency.
By tailoring the orientation of the graphene ribbons with respect
to an array of subwavelength bimetallic electrodes, we achieve a condition
in which the plasmonic mode can be efficiently excited by an incident
wave polarized perpendicular to the electrode array, while the resulting
photothermal voltage can be observed between the outermost electrodes