2,127 research outputs found
Observation of an optical event horizon in a silicon-on-insulator photonic wire waveguide
We report on the first experimental observation of an optical analogue of an event horizon in integrated nanophotonic waveguides, through the reflection of a continuous wave on an intense pulse. The experiment is performed in a dispersion-engineered silicon-on-insulator waveguide. In this medium, solitons do not suffer from Raman induced self-frequency shift as in silica fibers, a feature that is interesting for potential applications of optical event horizons. As shown by simulations, this also allows the observation of multiple reflections at the same time on fundamental solitons ejected by soliton fission.SCOPUS: ar.jhttp://www.opticsexpress.org/abstract.cfm?URIinfo:eu-repo/semantics/publishe
High-speed tunable photonic crystal fiber-based femtosecond soliton source without dispersion pre-compensation
We present a high-speed wavelength tunable photonic crystal fiber-based
source capable of generating tunable femtosecond solitons in the infrared
region. Through measurements and numerical simulation, we show that both the
pulsewidth and the spectral width of the output pulses remain nearly constant
over the entire tuning range from 860 to 1160 nm. This remarkable behavior is
observed even when pump pulses are heavily chirped (7400 fs^2), which allows to
avoid bulky compensation optics, or the use of another fiber, for dispersion
compensation usually required by the tuning device.Comment: 8 pages, 11 figure
29 W High power CW supercontinuum source.
Submitted versio
Understanding the dynamics of photoionization-induced solitons in gas-filled hollow-core photonic crystal fibers
We present in detail our developed model [Saleh et al., Phys. Rev. Lett. 107]
that governs pulse propagation in hollow-core photonic crystal fibers filled by
an ionizing gas. By using perturbative methods, we find that the
photoionization process induces the opposite phenomenon of the well-known Raman
self-frequency red-shift of solitons in solid-core glass fibers, as was
recently experimentally demonstrated [Hoelzer et al., Phys. Rev. Lett. 107].
This process is only limited by ionization losses, and leads to a constant
acceleration of solitons in the time domain with a continuous blue-shift in the
frequency domain. By applying the Gagnon-B\'{e}langer gauge transformation,
multi-peak `inverted gravity-like' solitary waves are predicted. We also
demonstrate that the pulse dynamics shows the ejection of solitons during
propagation in such fibers, analogous to what happens in conventional
solid-core fibers. Moreover, unconventional long-range non-local interactions
between temporally distant solitons, unique of gas plasma systems, are
predicted and studied. Finally, the effects of higher-order dispersion
coefficients and the shock operator on the pulse dynamics are investigated,
showing that the resonant radiation in the UV [Joly et al., Phys. Rev. Lett.
106] can be improved via plasma formation.Comment: 9 pages, 10 figure
Optical Cherenkov radiation by cascaded nonlinear interaction: an efficient source of few-cycle energetic near- to mid-IR pulses
When ultrafast noncritical cascaded second-harmonic generation of energetic
femtosecond pulses occur in a bulk lithium niobate crystal optical Cherenkov
waves are formed in the near- to mid-IR. Numerical simulations show that the
few-cycle solitons radiate Cherenkov (dispersive) waves in the
\lambda=2.2-4.5\mic range when pumping at \lambda_1=1.2-1.8\mic. The exact
phase-matching point depends on the soliton wavelength, and we show that a
simple longpass filter can separate the Cherenkov waves from the solitons. The
Cherenkov waves are born few-cycle with an excellent Gaussian pulse shape, and
the conversion efficiency is up to 25%. Thus, optical Cherenkov waves formed
with cascaded nonlinearities could become an efficient source of energetic
near- to mid-IR few-cycle pulses.Comment: Extended version of Nonlinear Optics 2011 contribution
http://www.opticsinfobase.org/abstract.cfm?URI=NLO-2011-NTuA7. Submitted for
Optics Express special issue for NLO conferenc
Information Transmission using the Nonlinear Fourier Transform, Part III: Spectrum Modulation
Motivated by the looming "capacity crunch" in fiber-optic networks,
information transmission over such systems is revisited. Among numerous
distortions, inter-channel interference in multiuser wavelength-division
multiplexing (WDM) is identified as the seemingly intractable factor limiting
the achievable rate at high launch power. However, this distortion and similar
ones arising from nonlinearity are primarily due to the use of methods suited
for linear systems, namely WDM and linear pulse-train transmission, for the
nonlinear optical channel. Exploiting the integrability of the nonlinear
Schr\"odinger (NLS) equation, a nonlinear frequency-division multiplexing
(NFDM) scheme is presented, which directly modulates non-interacting signal
degrees-of-freedom under NLS propagation. The main distinction between this and
previous methods is that NFDM is able to cope with the nonlinearity, and thus,
as the the signal power or transmission distance is increased, the new method
does not suffer from the deterministic cross-talk between signal components
which has degraded the performance of previous approaches. In this paper,
emphasis is placed on modulation of the discrete component of the nonlinear
Fourier transform of the signal and some simple examples of achievable spectral
efficiencies are provided.Comment: Updated version of IEEE Transactions on Information Theory, vol. 60,
no. 7, pp. 4346--4369, July, 201
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