1,136 research outputs found
Coupled-mode theory for periodic side-coupled microcavity and photonic crystal structures
We use a phenomenological Hamiltonian approach to derive a set of coupled
mode equations that describe light propagation in waveguides that are
periodically side-coupled to microcavities. The structure exhibits both Bragg
gap and (polariton like) resonator gap in the dispersion relation. The origin
and physical significance of the two types of gaps are discussed. The
coupled-mode equations derived from the effective field formalism are valid
deep within the Bragg gaps and resonator gaps.Comment: 13 pages, 6 figure
Nonlinear and Quantum Optics with Whispering Gallery Resonators
Optical Whispering Gallery Modes (WGMs) derive their name from a famous
acoustic phenomenon of guiding a wave by a curved boundary observed nearly a
century ago. This phenomenon has a rather general nature, equally applicable to
sound and all other waves. It enables resonators of unique properties
attractive both in science and engineering. Very high quality factors of
optical WGM resonators persisting in a wide wavelength range spanning from
radio frequencies to ultraviolet light, their small mode volume, and tunable
in- and out- coupling make them exceptionally efficient for nonlinear optical
applications. Nonlinear optics facilitates interaction of photons with each
other and with other physical systems, and is of prime importance in quantum
optics. In this paper we review numerous applications of WGM resonators in
nonlinear and quantum optics. We outline the current areas of interest,
summarize progress, highlight difficulties, and discuss possible future
development trends in these areas.Comment: This is a review paper with 615 references, submitted to J. Op
Feasibility of UV lasing without inversion in mercury vapor
We investigate the feasibility of UV lasing without inversion at a wavelength
of nm utilizing interacting dark resonances in mercury vapor. Our
theoretical analysis starts with radiation damped optical Bloch equations for
all relevant 13 atomic levels. These master equations are generalized by
considering technical phase noise of the driving lasers. From the Doppler
broadened complex susceptibility we obtain the stationary output power from
semiclassical laser theory. The finite overlap of the driving Gaussian laser
beams defines an ellipsoidal inhomogeneous gain distribution. Therefore, we
evaluate the intra-cavity field inside a ring laser self-consistently with
Fourier optics. This analysis confirms the feasibility of UV lasing and reveals
its dependence on experimental parameters.Comment: changes were made according to reviewer comments (accepted for
publication in JOSA B
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
Modal analysis of semiconductor lasers with nonplanar mirrors
We present a formalism for analyzing laser resonators which possess nonplanar mirrors and lateral waveguiding [e.g., an unstable resonator semiconductor laser (URSL)]. The electric field is expanded in lateral modes of the complex-index waveguide and is required to reproduce itself after, one roundtrip of the cavity. We show how the waveguide modes, their gain and loss, and hence the criterion for truncation of the infinite set of modes can be derived from the Green's function of the one-dimensional eigenvalue equation for the waveguide. Examples are presented for three cases of interest - a purely gain-guided URSL, an index-guided URSL, and a gain-guided tilted-mirror resonator. We compare theoretical calculations to previous experiments
Utilising optical Kerr microresonators for polarisation control, logic gates, and quantum optics applications
When high intensities of light are focused inside of a medium, strange effects occur. Light can self-interact. It can be slowed down based on how bright it is, it can be made to go in one direction but not the other, and it can even be made to c change colour.
It is hard to imagine how the world would look if these were effects that we experienced in our everyday lives. Fortunately, it takes a significant amount of effort to make the conditions right for such events to occur, specifically, with high optical intensities required. This thesis details some of these efforts.
In this work, I present some applications of Kerr microresonantor based nonlinear and quantum optics. Microresonators are minute devices that can be integrated in photonic circuits. They trap and guide light on a repeating path, with each roundtrip leading to an increase in intensity until nonlinear effects start to occur.
I start by explaining how such resonators work, are fabricated, and how nonlinear effects can manifest. Next, an all-optical polarisation controller is introduced, in which the nonlinear splitting of otherwise degenerate polarisation modes is employed. This device could find application in integrated photonic circuits that require fast response times. A similar effect, but this time for counter-propagating light, is then used to demonstrate an all-optical, universal logic gate. Interestingly, a set of such logic gates could be used for the on-chip routing of optical signals to provide low-latency communications for telecoms and distributed computing. Finally, the quantum nature of these nonlinearities is explored, first with the calculation of multi-modal entanglement metrics before then discussing work that is progressing towards a single-photon source. These phenomena show promise for integration into future quantum technologies, in particular in secure quantum communications and for state generation for quantum information processing.Open Acces
Simulation of continuous-wave solid-state laser resonators using field tracing and a fully vectorial fox-li algorithm
In this PHD thesis the scalar Fox and Li algorithm for the dominant transversal resonator eigenmode calculation is generalized to a fully vectorial field tracing concept. Therefore Fox and Li’s scalar integral equation is reformulated to a set of coupled operator equations. The introduction of a field tracing round trip operator concept shows that, in principle, any modeling technique which can be formulated to operate for electromagnetic fields can be used to simulate light propagation through the different subdomains of the resonator. This allows a flexible, fast, and accurate simulation of the fully vectorial dominant transversal resonator eigenmode. Several examples are presented to demonstrate the flexibility and accuracy of the field tracing approach
Topological Photonics
Topological photonics is a rapidly emerging field of research in which
geometrical and topological ideas are exploited to design and control the
behavior of light. Drawing inspiration from the discovery of the quantum Hall
effects and topological insulators in condensed matter, recent advances have
shown how to engineer analogous effects also for photons, leading to remarkable
phenomena such as the robust unidirectional propagation of light, which hold
great promise for applications. Thanks to the flexibility and diversity of
photonics systems, this field is also opening up new opportunities to realize
exotic topological models and to probe and exploit topological effects in new
ways. This article reviews experimental and theoretical developments in
topological photonics across a wide range of experimental platforms, including
photonic crystals, waveguides, metamaterials, cavities, optomechanics, silicon
photonics, and circuit QED. A discussion of how changing the dimensionality and
symmetries of photonics systems has allowed for the realization of different
topological phases is offered, and progress in understanding the interplay of
topology with non-Hermitian effects, such as dissipation, is reviewed. As an
exciting perspective, topological photonics can be combined with optical
nonlinearities, leading toward new collective phenomena and novel strongly
correlated states of light, such as an analog of the fractional quantum Hall
effect.Comment: 87 pages, 30 figures, published versio
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