141 research outputs found
Light localization induced enhancement of third order nonlinearities in a GaAs photonic crystal waveguide
Nonlinear propagation experiments in GaAs photonic crystal waveguides (PCW)
were performed, which exhibit a large enhancement of third order
nonlinearities, due to light propagation in a slow mode regime, such as
two-photon absorption (TPA), optical Kerr effect and refractive index changes
due to TPA generated free-carriers. A theoretical model has been established
that shows very good quantitative agreement with experimental data and
demonstrates the important role that group velocity plays. These observations
give a strong insight into the use of PCWs for optical switching devices.Comment: 6 page
GaAs photonic crystal cavity with ultra-high Q: microwatt nonlinearity at 1.55 m
We have realized and measured a GaAs nanocavity in a slab photonic crystal
based on the design by Kuramochi et al. [Appl. Phys.Lett., \textbf{88}, 041112,
(2006)]. We measure a quality factor Q=700,000, which proves that ultra-high Q
nanocavities are also feasible in GaAs. We show that, due to larger two-photon
absorption (TPA) in GaAs, nonlinearities appear at the microwatt-level and will
be more functional in gallium arsenide than in silicon nanocavities.Comment: 3 pages, 2 figures, accepted for publication in Optics Letter
Measurement of the linear thermo-optical coefficient of GaInP using photonic crystal nanocavities
GaInP is a promising candidate for thermally tunable
nanophotonic devices due to its low thermal conductivity. In this work we study
its thermo-optical response. We obtain the linear thermo-optical coefficient
by investigating the transmission
properties of a single mode-gap photonic crystal nanocavity.Comment: 7 pages, 4 figure
Oscillatory dynamics in nanocavities with noninstantaneous Kerr response
We investigate the impact of a finite response time of Kerr nonlinearities
over the onset of spontaneous oscillations (self-pulsing) occurring in a
nanocavity. The complete characterization of the underlying Hopf bifurcation in
the full parameter space allows us to show the existence of a critical value of
the response time and to envisage different regimes of competition with
bistability. The transition from a stable oscillatory state to chaos is found
to occur only in cavities which are detuned far off-resonance, which turns out
to be mutually exclusive with the region where the cavity can operate as a
bistable switch
Tuning out disorder-induced localization in nanophotonic cavity arrays
Weakly coupled high-Q nanophotonic cavities are building blocks of slow-light
waveguides and other nanophotonic devices. Their functionality critically
depends on tuning as resonance frequencies should stay within the bandwidth of
the device. Unavoidable disorder leads to random frequency shifts which cause
localization of the light in single cavities. We present a new method to finely
tune individual resonances of light in a system of coupled nanocavities. We use
holographic laser-induced heating and address thermal crosstalk between
nanocavities using a response matrix approach. As a main result we observe a
simultaneous anticrossing of 3 nanophotonic resonances, which were initially
split by disorder.Comment: 11 page
Dispersion of coupled mode-gap cavities
The dispersion of a CROW made of photonic crystal mode-gap cavities is
pronouncedly asymmetric. This asymmetry cannot be explained by the standard
tight binding model. We show that the fundamental cause of the asymmetric
dispersion is the fact that the cavity mode profile itself is dispersive, i.e.,
the mode wave function depends on the driving frequency, not the
eigenfrequency. This occurs because the photonic crystal cavity resonances do
not form a complete set. By taking into account the dispersive mode profile, we
formulate a mode coupling model that accurately describes the asymmetric
dispersion without introducing any new free parameters.Comment: 4 pages, 4 figure
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