In JoVE (1)

Other Publications (28)

Articles by Tal Carmon in JoVE

Other articles by Tal Carmon on PubMed

Collisions Between Optical Spatial Solitons Propagating in Opposite Directions

Physical Review Letters. Sep, 2002  |  Pubmed ID: 12225028

We formulate the theory describing the evolution and interactions between optical spatial solitons that propagate in opposite directions. We show that coherent collisions between counterpropagating solitons give rise to a new focusing mechanism resulting from the interference between the beams, and that interactions between such solitons are insensitive to the relative phase between the beams.

Pattern Formation in a Cavity Longer Than the Coherence Length of the Light in It

Physical Review Letters. Oct, 2002  |  Pubmed ID: 12398602

We study, theoretically and experimentally, the evolution of patterns in a passive nonlinear cavity that is longer than the coherence length of the light circulating in it. The patterns exhibit spatial line narrowing as the feedback is increased, resembling the line narrowing in lasers.

Photorefractive Solitons and Light-induced Resonance Control in Semiconductor CdZnTe

Optics Letters. Jul, 2002  |  Pubmed ID: 18026411

We demonstrate the formation of (1+1) - and (2+1) -dimensional solitons in photorefractive CdZnTe:V, exploiting the intensity-resonant behavior of the space-charge field. We control the resonance optically, facilitating a 10-mus soliton formation times with very low optical power.

Spatial Vector Solitons Consisting of Counterpropagating Fields

Optics Letters. Nov, 2002  |  Pubmed ID: 18033429

We present the experimental observation of a spatial vector soliton formed by counterpropagation of coherent optical fields. This is to our knowledge the first observation of a vector soliton in which the induced waveguide (potential) is periodic in the propagation direction. This vector soliton induces a waveguide and a thick grating within the waveguide, which can be used as a tunable optical waveguide filter.

Holographic Solitons

Optics Letters. Nov, 2002  |  Pubmed ID: 18033435

We propose a new kind of an optical spatial soliton: the holographic soliton. This soliton consists of two mutually coherent field components that interfere, induce a periodic change in the refractive index, and simultaneously are Bragg diffracted from the grating. Holographic solitons are formed when the broadening tendency of diffraction is balanced by phase modulation that is due to Bragg diffraction from the induced grating. Holographic solitons are solely supported by cross-phase modulation arising from the induced grating, not involving self-phase modulation at all.

Observation of Discrete Solitons in Optically Induced Real Time Waveguide Arrays

Physical Review Letters. Jan, 2003  |  Pubmed ID: 12570547

We report the first experimental observation of discrete solitons in an array of optically induced waveguides. The waveguide lattice is induced in real time by illuminating a photorefractive crystal with a pair of interfering plane waves. We demonstrate two types of bright discrete solitons: in-phase self-localized states and the staggered (pi out-of-phase) soliton family. This experiment is the first observation of bright staggered solitons in any physical system. Our scheme paves the way for reconfigurable focusing and defocusing photonic lattices where low-power (mW) discrete solitons can be thoroughly investigated.

Cavity Pattern Formation with Incoherent Light

Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics. Jul, 2003  |  Pubmed ID: 12935279

We study the propagation dynamics of an incoherent light beam circulating in a passive cavity containing noninstantaneous nonlinear media. It is shown that patterns form in this cavity in spite of spatial incoherence of the light. We show that the pattern formation process is always associated with two consecutive thresholds. The first (instability) threshold is unaffected by the cavity boundary conditions, whereas the second threshold is induced by the feedback through the interplay of nonlinear gain and cavity loss.

Observation of Locked Optical Kink-antikink Spatial Shock Waves

Physical Review Letters. Sep, 2003  |  Pubmed ID: 14525304

We report the first experimental observation of optical spatial shock-wave pairs. The shock waves consist of two coupled kink and antikink beams that remain locked to each other throughout propagation in a nonlinear diffusion-driven photorefractive crystal. These coupled shock-wave pairs move undistorted at angles that fall outside their original angular sector of propagation.

Observation of Elliptic Incoherent Spatial Solitons

Optics Letters. Jun, 2004  |  Pubmed ID: 15209261

We present the first experimental observation of spatially incoherent elliptic solitons. We use partially spatially incoherent light with anisotropic correlation statistics and observe elliptic solitons supported by the photorefractive screening nonlinearity.

Spontaneous Pattern Formation with Incoherent White Light

Physical Review Letters. Nov, 2004  |  Pubmed ID: 15601091

We present the first experimental observation of modulation instability and spontaneous pattern formation with incoherent white light emitted from an incandescent light bulb. We show experimentally that modulation instability of white light propagating in a noninstantaneous self-focusing medium is a collective effect, where the entire temporal spectrum of the light beam becomes unstable at the same threshold value and collectively forms a pattern with a single periodicity. We experimentally demonstrate that the temporal spectrum of the evolving perturbation self-adjusts to match the collective pattern formation phenomenon.

Spontaneous Pattern Formation in a Cavity with Incoherent Light

Optics Express. Jul, 2004  |  Pubmed ID: 19483875

We present the first experimental observation of spontaneous pattern formation in a nonlinear optical cavity in which the circulating light is both spatially and temporally incoherent.

Dynamical Thermal Behavior and Thermal Self-stability of Microcavities

Optics Express. Oct, 2004  |  Pubmed ID: 19484026

As stability and continuous operation are important for almost any use of a microcavity, we demonstrate here experimentally and theoretically a self-stable equilibrium solution for a pump-microcavity system. In this stable equilibrium, intensity- and wavelength-perturbations cause a small thermal resonant-drift that is enough to compensate for the perturbation (noises); consequently the cavity stays warm and loaded as perturbations are self compensated. We also compare here, our theoretical prediction for the thermal line broadening (and for the wavelength hysteretic response) to experimental results.

Observation of Random-phase Lattice Solitons

Nature. Feb, 2005  |  Pubmed ID: 15690035

The coherence of waves in periodic systems (lattices) is crucial to their dynamics, as interference effects, such as Bragg reflections, largely determine their propagation. Whereas linear systems allow superposition, nonlinearity introduces a non-trivial interplay between localization effects, coupling between lattice sites, and incoherence. Until recently, all research on solitary waves (solitons) in nonlinear lattices has involved only coherent waves. In such cases, linear dispersion or diffraction of wave packets can be balanced by nonlinear effects, resulting in coherent lattice (or 'discrete') solitons; these have been studied in many branches of science. However, in most natural systems, waves with only partial coherence are more common, because fluctuations (thermal, quantum or some other) can reduce the correlation length to a distance comparable to the lattice spacing. Such systems should support random-phase lattice solitons displaying distinct features. Here we report the experimental observation of random-phase lattice solitons, demonstrating their self-trapping and local periodicity in real space, in addition to their multi-peaked power spectrum in momentum space. We discuss the relevance of such solitons to other nonlinear periodic systems in which fluctuating waves propagate, such as atomic systems, plasmas and molecular chains.

Temporal Behavior of Radiation-pressure-induced Vibrations of an Optical Microcavity Phonon Mode

Physical Review Letters. Jun, 2005  |  Pubmed ID: 16090397

We analyze experimentally and theoretically mechanical oscillation within an optical cavity stimulated by the pressure of circulating optical radiation. The resulting radio frequency cavity vibrations (phonon mode) cause modulation of the incident, continuous-wave (cw) input pump beam. Furthermore, with increasing cw pump power, an evolution from sinusoidal modulation to random oscillations is observed in the pump power coupled from the resonator. The temporal evolution with pump power is studied, and agreement was found with theory. In addition to applications in quantum optomechanics, the present work suggests that radiation-pressure-induced effects can establish a practical limit for the miniaturization of optical silica microcavities.

Solitons in Nonlinear Media with an Infinite Range of Nonlocality: First Observation of Coherent Elliptic Solitons and of Vortex-ring Solitons

Physical Review Letters. Nov, 2005  |  Pubmed ID: 16384143

We present an experimental study on wave propagation in highly nonlocal optically nonlinear media, for which far-away boundary conditions significantly affect the evolution of localized beams. As an example, we set the boundary conditions to be anisotropic and demonstrate the first experimental observation of coherent elliptic solitons. Furthermore, exploiting the natural ability of such nonlinearities to eliminate azimuthal instabilities, we perform the first observation of stable vortex-ring solitons. These features of highly nonlocal nonlinearities affected by far-away boundary conditions open new directions in nonlinear science by facilitating remote control over soliton propagation.

Feedback Control of Ultra-high-Q Microcavities: Application to Micro-Raman Lasers and Microparametric Oscillators

Optics Express. May, 2005  |  Pubmed ID: 19495260

We demonstrate locking of an on-chip, high-Q toroidal-cavity to a pump laser using two, distinct methods: coupled power stabilization and wavelength locking of pump laser to the microcavity. In addition to improvements in operation of previously demonstrated micro-Raman and micro-OPO lasers, these techniques have enabled observation of a continuous, cascaded nonlinear process in which photons generated by optical parametric oscillations (OPO) function as a pump for Raman lasing. Dynamical behavior of the feedback control systems is also shown including the interplay between the control loop and the thermal nonlinearity. The demonstrated stabilization loop is essential for studying generation of nonclassical states using a microcavity optical parametric oscillator.

Modal Spectroscopy of Optoexcited Vibrations of a Micron-scale On-chip Resonator at Greater Than 1 GHz Frequency

Physical Review Letters. Mar, 2007  |  Pubmed ID: 17501123

We analyze experimentally and theoretically >1 GHz optoexcited mechanical vibration in an on-chip micron-scaled sphere. Different eigen-mechanical modes are excited upon demand by the centrifugal radiation pressure of the optical whispering-gallery-mode, enabling an optomechanical modal spectroscopy investigation of many vibrational modes. Spectral analysis of the light emitted from the device enables deduction of its natural vibrational modes in analogy with spectroscopy of a molecule's vibrational levels, and its eccentricity perturbation is shown to induce spectral splitting.

Chaotic Quivering of Micron-scaled On-chip Resonators Excited by Centrifugal Optical Pressure

Physical Review Letters. Apr, 2007  |  Pubmed ID: 17501457

Opto-mechanical chaotic oscillation of an on-chip resonator is excited by the radiation-pressure nonlinearity. Continuous optical input, with no external feedback or modulation, excites chaotic vibrations in very different geometries of the cavity (both tori and spheres) and shows that opto-mechanical chaotic oscillations are an intrinsic property of optical microcavities. Measured phenomena include period doubling, a spectral continuum, aperiodic oscillations, and complex trajectories. The rate of exponential divergence from a perturbed initial condition (Lyapunov exponent) is calculated. Continuous improvements in cavities mean that such chaotic oscillations can be expected in the future with many other platforms, geometries, and frequency spans.

Wavelength-independent Coupler from Fiber to an On-chip Cavity, Demonstrated over an 850nm Span

Optics Express. Jun, 2007  |  Pubmed ID: 19547095

A robust wide band (850 nm) fiber coupler to a whispering-gallery cavity with ultra-high quality factor is experimentally demonstrated. The device trades off ideality for broad-band, efficient input coupling. Output coupling efficiency can remain high enough for practical applications wherein pumping and power extraction must occur over very broad wavelength spans.

Static Envelope Patterns in Composite Resonances Generated by Level Crossing in Optical Toroidal Microcavities

Physical Review Letters. Mar, 2008  |  Pubmed ID: 18352190

We study level crossing in the optical whispering-gallery (WG) modes by using toroidal microcavities. Experimentally, we image the stationary envelope patterns of the composite optical modes that arise when WG modes of different wavelengths coincide in frequency. Numerically, we calculate crossings of levels that correspond with the observed degenerate modes, where our method takes into account the not perfectly transverse nature of their field polarizations. In addition, we analyze anticrossing with a large avoidance gap between modes of the same azimuthal number.

Photonic Micro-electromechanical Systems Vibrating at X-band (11-GHz) Rates

Physical Review Letters. Mar, 2009  |  Pubmed ID: 19392199

We report on an opto-mechanical resonator with vibration excited by compressive radiation pressure via stimulated Brillouin scattering [SBS]. We experimentally excite a mechanical whispering-gallery mode (WGM) from an optical WGM and detect vibration via the red Doppler shifted (Stokes) light it scatters. We numerically solve the stress-strain equation to calculate the circumferentially circulating mechanical WGM and reveal mechanical WGMs with a variety of transverse shapes. Frequency in our device is limited by the shortest optical wavelength it can transmit, irrespective of device size.

Direct Imaging of Tunneling from a Potential Well

Optics Express. Oct, 2009  |  Pubmed ID: 20372652

We experimentally map the wavefunction in the vicinity of a radial potential well. We photograph light intensity near the tunneling region as well as measure the spiraling phase structure via interference with a reference wave. This spiraling phase structure is required for conservation of angular momentum. The experimental image reveals the non-intuitive emission of light from a region in space that is empty of material and relatively far from the device.

Precession Optomechanics

Optics Express. May, 2011  |  Pubmed ID: 21643161

We propose a light-structure interaction that utilizes circularly polarized light to deform a slightly bent waveguide. The mechanism allows for flipping the direction of deformation upon changing the binary polarization state of light from -ℏ to +ℏ.

Stimulated Optomechanical Excitation of Surface Acoustic Waves in a Microdevice

Nature Communications. 2011  |  Pubmed ID: 21792182

Stimulated Brillouin interaction between sound and light, known to be the strongest optical nonlinearity common to all amorphous and crystalline dielectrics, has been widely studied in fibres and bulk materials but rarely in optical microresonators. The possibility of experimentally extending this principle to excite mechanical resonances in photonic microsystems, for sensing and frequency reference applications, has remained largely unexplored. The challenge lies in the fact that microresonators inherently have large free spectral range, whereas the phase-matching considerations for the Brillouin process require optical modes of nearby frequencies but with different wave vectors. Here we rely on high-order transverse optical modes to relax this limitation and report the experimental excitation of mechanical resonances ranging from 49 to 1,400 MHz by using forward Brillouin scattering. These natural mechanical resonances are excited in ∼100 μm silica microspheres, and are of a surface-acoustic whispering-gallery type.

Surface Optomechanics: Calculating Optically Excited Acoustical Whispering Gallery Modes in Microspheres

Optics Express. Jul, 2011  |  Pubmed ID: 21934788

Stimulated Brillouin scattering recently allowed experimental excitation of surface acoustic resonances in micro-devices, enabling vibration at rates in the range of 50 MHz to 12 GHz. The experimental availability of such mechanical whispering gallery modes in photonic-MEMS raises questions on their structure and spectral distribution. Here we calculate the form and frequency of such vibrational surface whispering gallery modes, revealing diverse types of surface vibrations including longitudinal, transverse, and Rayleigh-type deformations. We parametrically investigate these various modes by changing their orders in the azimuthal, radial, and polar directions to reveal different vibrational structures including mechanical resonances that are localized near the interface with the environment where they can sense changes in the surroundings.

Continuous-wave Ultraviolet Emission Through Fourth-harmonic Generation in a Whispering-gallery Resonator

Optics Express. Nov, 2011  |  Pubmed ID: 22109440

We experimentally demonstrate continuous-wave ultraviolet emission through forth-harmonic generation in a millimeter-scale lithium niobate whispering-gallery resonator pumped with a telecommunication-compatible infrared source. The whispering-gallery resonator provides four spectral lines at ultraviolet, visible, near-infrared and infrared, which are equally spaced in frequency via the cascaded-harmonic process and span a 2-octave frequency band. Our technique relies on a variable crystal poling and high transverse order of the modes for phase-matching and a resonator quality factor of over 10(7) to allow cascaded-harmonic generation up to the fourth-harmonic at input pump powers as low as 200 mW. The compact size of the whispering gallery resonator pumped at telecommunication-compatible infrared wavelengths and the low pump power requirement make our device a promising ultraviolet light source for information storage, microscopy, and chemical analysis.

Brillouin Cavity Optomechanics with Microfluidic Devices

Nature Communications. 2013  |  Pubmed ID: 23744103

Cavity optomechanics allows the parametric coupling of phonon- and photon-modes in microresonators and is presently investigated in a broad variety of solid-state systems. Optomechanics with superfluids has been proposed as a path towards ultra-low optical- and mechanical-dissipation. However, there have been no optomechanics experiments reported with non-solid phases of matter. Direct liquid immersion of optomechanics experiments is challenging, as the acoustic energy simply leaks out to the higher-impedance liquid surrounding the device. Here we confine liquids within hollow resonators to circumvent this issue and to enable optical excitation of mechanical whispering-gallery modes at frequencies ranging from 2 to 11,000 MHz. Our device enables optomechanical investigation with liquids, while light is conventionally coupled from the outer dry side of the capillary, and liquids are provided by means of a standard microfluidic inlet.

Finite Element Simulation of a Perturbed Axial-symmetric Whispering-gallery Mode and Its Use for Intensity Enhancement with a Nanoparticle Coupled to a Microtoroid

Optics Express. Jun, 2013  |  Pubmed ID: 23787608

We present an optical mode solver for a whispering gallery resonator coupled to an adjacent arbitrary shaped nano-particle that breaks the axial symmetry of the resonator. Such a hybrid resonator-nanoparticle is similar to what was recently used for bio-detection and for field enhancement. We demonstrate our solver by parametrically studying a toroid-nanoplasmonic device and get the optimal nano-plasmonic size for maximal enhancement. We investigate cases near a plasmonic resonance as well as far from a plasmonic resonance. Unlike common plasmons that typically benefit from working near their resonance, here working far from plasmonic resonance provides comparable performance. This is because the plasmonic resonance enhancement is accompanied by cavity quality degradation through plasmonic absorption.

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