345 research outputs found
Quantum Dynamics of Kerr Optical Frequency Combs below and above Threshold: Spontaneous Four-Wave-Mixing, Entanglement and Squeezed States of Light
In this article, we use quantum Langevin equations to provide a theoretical
understanding of the non-classical behavior of Kerr optical frequency combs
when pumped below and above threshold. In the configuration where the system is
under threshold, the pump field is the unique oscillating mode inside the
resonator, and triggers the phenomenon of spontaneous four-wave mixing, where
two photons from the pump are symmetrically up- and down-converted in the
Fourier domain. This phenomenon can only be understood and analyzed from a
fully quantum perspective as a consequence of the coupling between the field of
the central (pumped) mode and the vacuum fluctuations of the various sidemodes.
We analytically calculate the power spectra of the spontaneous emission noise,
and we show that these spectra can be either single- or double peaked depending
on the parameters of the system. We also calculate as well the overall
spontaneous noise power per sidemode, and propose simplified analytical
expressions for some particular cases. In the configuration where the system is
pumped above threshold, we investigate the phenomena of quantum correlations
and multimode squeezed states of light that can occur in the Kerr frequency
combs originating from stimulated four-wave mixing. We show that for all
stationary spatio-temporal patterns, the side-modes that are symmetrical
relatively to the pumped mode in the frequency domain display quantum
correlations that can lead to squeezed states of light. We also explicitly
determine the phase quadratures leading to photon entanglement, and
analytically calculate their quantum noise spectra. We finally discuss the
relevance of Kerr combs for quantum information systems at optical
telecommunication wavelengths, below and above threshold.Comment: 27 pages, 11 figure
On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range
Optical whispering gallery mode (WGM) resonators have been very attracting
platforms for versatile Kerr frequency comb generations. We report a systematic
study on the material dispersion of various optical materials that are capable
of supporting quality factors above . Using an analytical approximation
of WGM resonant frequencies in disk resonators, we investigate the effect of
the geometry and transverse mode order on the total group-velocity dispersion
(). We demonstrate that the major radii and the radial mode indices play
an important role in tailoring the of WGM resonators. In particular, our
study shows that in WGM disk-resonators, the polar families of modes have very
similar , while the radial families of modes feature dispersion values
that can differ by up to several orders of magnitude. The effect of these giant
dispersion shifts are experimentally evidenced in Kerr comb generation with
magnesium fluoride. From a more general perspective, this critical feature
enables to push the zero-dispersion wavelength of fluorite crystals towards the
mid-infrared (mid-IR) range, thereby allowing for efficient Kerr comb
generation in that spectral range. We show that barium fluoride is the most
interesting crystal in this regard, due to its zero dispersion wavelength
() at and an optimal dispersion profile in the mid-IR
regime. We expect our results to facilitate the design of different platforms
for Kerr frequency comb generations in both telecommunication and mid-IR
spectral ranges
Routes to spatiotemporal chaos in Kerr optical frequency combs
We investigate the various routes to spatiotemporal chaos in Kerr optical
frequency combs obtained through pumping an ultra-high quality
whispering-gallery mode resonator with a continuous-wave laser. The
Lugiato-Lefever model is used to build bifurcation diagrams with regards to the
parameters that are externally controllable, namely, the frequency and the
power of the pumping laser. We show that the spatiotemporal chaos emerging from
Turing patterns and solitons display distinctive dynamical features.
Experimental spectra of chaotic Kerr combs are also presented for both cases,
in excellent agreement with theoretical spectra
Spatiotemporal Model for Kerr Comb Generation in Whispering Gallery Mode Resonators
We establish an exact partial differential equation to model Kerr comb
generation in whispering-gallery mode resonators. This equation is a variant of
the Lugiato-Lefever equation that includes higher-order dispersion and
nonlinearity. This spatio-temporal model, whose main variable is the total
intracavity field, is significantly more suitable than the modal expansion
approach for the theoretical understanding and the numerical simulation of
wide-span combs. It allows us to explore pulse formation in which a large
number of modes interact cooperatively. This versatile approach can be
straightforwardly extended to include higher-order dispersion, as well as other
phenomena like Raman, Brillouin and Rayleigh scattering. We demonstrate for the
first time that when the dispersion is anomalous, Kerr comb generation can
arise as the spectral signature of dissipative cavity solitons, leading to
wide-span combs with low pumping.Comment: 5 pages, 2 figure
Observation of Spatiotemporal Chaos Induced by a Cavity Soliton in a Fiber Ring Resonator
We report on the experimental observation of temporal cavity soliton
destabilization via spatiotemporal chaos in a coherently-driven optical fiber
ring resonator. Numerical simulations and theoretical analyses are in good
agreement with experimental observations.Comment: Submitted to CLEO US on 27/01/201
A Silicon-Based Monolithic Optical Frequency Comb Source
Recently developed techniques for generating precisely equidistant optical
frequencies over broad wavelength ranges are revolutionizing precision physical
measurement [1-3]. These frequency "combs" are produced primarily using
relatively large, ultrafast laser systems. However, recent research has shown
that broad-bandwidth combs can be produced using highly-nonlinear interactions
in microresonator optical parametric oscillators [4-11]. Such devices not only
offer the potential for developing extremely compact optical atomic clocks but
are also promising for astronomical spectroscopy [12-14], ultrashort pulse
shaping [15], and ultrahigh-speed communications systems. Here we demonstrate
the generation of broad-bandwidth optical frequency combs from a
CMOS-compatible integrated microresonator [16,17], which is a fully-monolithic
and sealed chip-scale device making it insensitive to the surrounding
environment. We characterize the comb quality using a novel self-referencing
method and verify that the comb line frequencies are equidistant over a
bandwidth that is nearly an order of magnitude larger than previous
measurements. In addition, we investigate the ultrafast temporal properties of
the comb and demonstrate its potential to serve as a chip-scale source of
ultrafast (sub-ps) pulses
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