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1.
Opt Express ; 28(24): 35833-35843, 2020 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-33379691

RESUMEN

Multimode interference (MMI) devices are key components in modern integrated photonic circuits. Here, we present acoustically tuned optical switches on an (Al,Ga)As platform that enable robust, compact and fast response systems improving on recently demonstrated technology. The device consists of a 2 × 2 MMI device fine-tuned in its center region by a focused surface acoustic wave (SAW) beam working in the low GHz range. In this way, we can tune the refractive index profile over a narrow modulation region and thus control the optical switching behaviour via the applied SAW intensity. Direct tuning of the MMI device avoids losses and phase errors inherent to arrayed waveguide based switches, while also reducing the dimensions of the photonic circuit.

2.
Phys Rev Lett ; 125(10): 107702, 2020 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-32955339

RESUMEN

We report on acoustically driven spin resonances in atomic-scale centers in silicon carbide at room temperature. Specifically, we use a surface acoustic wave cavity to selectively address spin transitions with magnetic quantum number differences of ±1 and ±2 in the absence of external microwave electromagnetic fields. These spin-acoustic resonances reveal a nontrivial dependence on the static magnetic field orientation, which is attributed to the intrinsic symmetry of the acoustic fields combined with the peculiar properties of a half-integer spin system. We develop a microscopic model of the spin-acoustic interaction, which describes our experimental data without fitting parameters. Furthermore, we predict that traveling surface waves lead to a chiral spin-acoustic resonance that changes upon magnetic field inversion. These results establish silicon carbide as a highly promising hybrid platform for on-chip spin-optomechanical quantum control enabling engineered interactions at room temperature.

3.
J Opt Soc Am A Opt Image Sci Vis ; 35(11): 1919-1928, 2018 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-30461852

RESUMEN

We investigate recording and erasure of photorefractive holographic gratings in an undoped Bi12TiO20 crystal in a moderate to high intensity regime of the recording beams at 639.7 nm without and with the action of laser pre-illumination at 532 nm. The detected hologram without pre-illumination indicates the participation of two photorefractive electronic gratings in its recording process, and the diffracted signal by itself exhibits a fivefold enhancement when the total intensity increases from 38.4 to 214.5 mW/cm2. The dependence of the measured total diffraction efficiency on intensity was investigated and showed linear behavior. At least three gratings are present in the regime of pre-illumination and participate in the writing and erasure of holographic mechanisms. Two of them are electronic, and one is hole-based, with a phase difference of Δϕ between them. The theoretical approach used to analyze the total diffraction efficiency based upon the photorefractivity standard model, and considering the presence of the three gratings, showed good agreement with the holographic erasure experimental data and permitted us to compute Δϕ, which exhibited strong and unusual dependence on the total intensity.

4.
Opt Express ; 23(16): 21213-31, 2015 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-26367971

RESUMEN

We demonstrate compact tunable phased-array wavelength-division multiplexers driven by surface acoustic waves (SAWs) in the low GHz range. The devices comprise two couplers, which respectively split and combine the optical signal, linked by an array of single-mode waveguides (WGs). Two different layouts are presented, in which multi-mode interference couplers or free propagating regions were separately employed as couplers. The multiplexers operate on five equally distributed wavelength channels, with a spectral separation of 2 nm. A standing SAW modulates the refractive index of the arrayed WGs. Each wavelength component periodically switches paths between the output channel previously asigned by the design and the adjacent channels, at a fixed applied acoustic power. The devices were monolithically fabricated on (Al,Ga)As. A good agreement between theory and experiment is achieved.

5.
Phys Rev Lett ; 115(25): 256401, 2015 Dec 18.
Artículo en Inglés | MEDLINE | ID: mdl-26722931

RESUMEN

We report propagating bound microcavity polariton soliton arrays consisting of multipeak structures either along (x) or perpendicular (y) to the direction of propagation. Soliton arrays of up to five solitons are observed, with the number of solitons controlled by the size and power of the triggering laser pulse. The breakup along the x direction occurs when the effective area of the trigger pulse exceeds the characteristic soliton size determined by polariton-polariton interactions. Narrowing of soliton emission in energy-momentum space indicates phase locking between adjacent solitons, consistent with numerical modeling which predicts stable multihump soliton solutions. In the y direction, the breakup originates from inhomogeneity across the wave front in the transverse direction which develops into a stable array only in the solitonic regime via phase-dependent interactions of propagating fronts.

6.
Phys Rev Lett ; 112(4): 046403, 2014 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-24580473

RESUMEN

We report on the spin properties of bright polariton solitons supported by an external pump to compensate losses. We observe robust circularly polarized solitons when a circularly polarized pump is applied, a result attributed to phase synchronization between nondegenerate TE and TM polarized polariton modes at high momenta. For the case of a linearly polarized pump, either σ+ or σ- circularly polarized bright solitons can be switched on in a controlled way by a σ+ or σ- writing beam, respectively. This feature arises directly from the widely differing interaction strengths between co- and cross-circularly polarized polaritons. In the case of orthogonally linearly polarized pump and writing beams, the soliton emission on average is found to be unpolarized, suggesting strong spatial evolution of the soliton polarization. The observed results are in agreement with theory, which predicts stable circularly polarized solitons and unstable linearly polarized solitons.

7.
Nanotechnology ; 25(13): 135204, 2014 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-24595075

RESUMEN

The oscillating piezoelectric fields accompanying surface acoustic waves are able to transport charge carriers in semiconductor heterostructures. Here, we demonstrate high-frequency (above 1 GHz) acoustic charge transport in GaAs-based nanowires deposited on a piezoelectric substrate. The short wavelength of the acoustic modulation, smaller than the length of the nanowire, allows the trapping of photo-generated electrons and holes at the spatially separated energy minima and maxima of conduction and valence bands, respectively, and their transport along the nanowire with a well defined acoustic velocity towards indium-doped recombination centers.

8.
Nat Commun ; 15(1): 5343, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38961065

RESUMEN

The harmonic modulation of coherent systems gives rise to a wealth of physical phenomena, e.g., the AC-Stark effect and Mollow triplets, with important implications for coherent control and frequency conversion. Here, we demonstrate a novel regime of temporal coherence in oscillators harmonically driven at extreme energy modulation amplitudes relative to the modulation quantum. The studies were carried out by modulating a confined exciton-polariton Bose-Einstein condensate (BEC) by an acoustic wave. Features of the new regime are the appearance, in the spectral domain, of a comb of resonances termed acceleration beats with energy spacing tunable by the modulation amplitude and, in the time domain, of temporal correlations at time scales much shorter than the acoustic period, which also depend on the modulation amplitude. These features are quantitatively accounted for by a theoretical framework, which associates the beats with accelerated energy-change rates during the harmonic cycle. These observations are underpinned by the high sensitivity of the BEC energy to the acoustic driving, which simultaneously preserves the BEC's temporal coherence. The acceleration beats are a general feature associated with accelerated energy changes: analogous features are thus also expected to appear under highly accelerated motion e.g., in connection with Cherenkov and Hawking radiation.

9.
Science ; 384(6699): 995-1000, 2024 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-38815032

RESUMEN

Time crystals (TCs) are many-body systems that display spontaneous breaking of time translation symmetry. We demonstrate a TC by using driven-dissipative condensates of microcavity exciton-polaritons, spontaneously formed from an incoherent particle bath. The TC phases are controlled by the power of a continuous-wave nonresonant optical drive exciting the condensate and the interaction with cavity phonons. Those phases are, for increasing power, Larmor-like precession of the condensate pseudo-spins-a signature of continuous TC; locking of the frequency of precession to self-sustained coherent phonons-stabilized TC; and doubling of TC's period by phonons-a discrete TC with continuous excitation. These results establish microcavity polaritons as a platform for the investigation of time-broken symmetry in nonhermitian systems.

10.
Braz J Biol ; 84: e278486, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38985059

RESUMEN

The present study evaluated the hematological, antiparasitic and growth responses in tambaqui (Colossoma macropomum) fed with diets supplemented with the microalgae Arthrospira platensis and Chlorella vulgaris (0%; 10% A. platensis; 10% C. vulgaris; and 5% A. platensis+5% C. vulgaris). Tambaqui (n=60, 62.57 ± 8.76 g) were fed for 20 days with experimental diets. Blood samples collection was done to determine hematological parameters, and gills were removed to identify and count monogenetic parasites. Supplementation with A. platensis 10% reduced red blood cells count, in consequence mean corpuscular volume and mean hemoglobin concentration increased. Total leukocyte, monocyte, eosinophil, and basophil counts reduced with the use of A. platensis. Higher monocytes, eosinophil, and basophil numbers in tambaqui fed with diet supplemented with 10% C. vulgaris were observed and may have been due to the presence of immunostimulants in this microalga composition. Reduction on total cholesterol in tambaqui that received both microalgae (A. platensis 5%+C. vulgaris 5%) may indicate that combined supplementation presented greater benefits to the health for C. macropomum than separately. Both microalgae were efficient against monogenetic parasites of tambaqui. Thus, the dietary use of the microalgae A. platensis and C. vulgaris provided immunostimulant and antiparasitic efficacy in C. macropomum.


Asunto(s)
Chlorella vulgaris , Spirulina , Chlorella vulgaris/química , Animales , Suplementos Dietéticos , Characiformes , Microalgas/química
11.
Opt Express ; 21(18): 21669-76, 2013 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-24104040

RESUMEN

Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180°-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms.

12.
Phys Rev Lett ; 111(14): 146401, 2013 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-24138259

RESUMEN

We report on the two-dimensional gap-soliton nature of exciton-polariton macroscopic coherent phases (PMCP) in a square lattice with a tunable amplitude. The resonantly excited PMCP forms close to the negative mass M point of the lattice band structure with energy within the lattice band gap and its wave function localized within a few lattice periods. The PMCPs are well described as gap solitons resulting from the interplay between repulsive polariton-polariton interactions and effective attractive forces due to the negative mass. The solitonic nature accounts for the reduction of the PMCP coherence length and optical excitation threshold with increasing lattice amplitude.

13.
Nano Lett ; 12(1): 252-8, 2012 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-22142481

RESUMEN

The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited carriers, as well as to spatially control exciton recombination in GaAs-based nanowires (NWs) on a subns time scale. The experiments are carried out in core-shell NWs transferred to a SAW delay line on a LiNbO(3) crystal. Carriers generated in the NW by a focused laser spot are acoustically transferred to a second location, leading to the remote emission of subns light pulses synchronized with the SAW phase. The dynamics of the carrier transport, investigated using spatially and time-resolved photoluminescence, is well-reproduced by computer simulations. The high-frequency contactless manipulation of carriers by SAWs opens new perspectives for applications of NWs in opto-electronic devices operating at gigahertz frequencies. The potential of this approach is demonstrated by the realization of a high-frequency source of antibunched photons based on the acoustic transport of electrons and holes in (In,Ga)As NWs.


Asunto(s)
Arsenicales/química , Arsenicales/efectos de la radiación , Cristalización/métodos , Galio/química , Galio/efectos de la radiación , Nanoestructuras/química , Nanoestructuras/efectos de la radiación , Sonicación , Sustancias Macromoleculares/química , Sustancias Macromoleculares/efectos de la radiación , Ensayo de Materiales , Conformación Molecular/efectos de la radiación , Nanoestructuras/ultraestructura , Tamaño de la Partícula , Fotones , Propiedades de Superficie/efectos de la radiación
14.
Nat Commun ; 14(1): 3485, 2023 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-37336923

RESUMEN

Lattices of exciton-polariton condensates represent an attractive platform for the study and implementation of non-Hermitian bosonic quantum systems with strong non-linear interactions. The possibility to actuate on them with a time dependent drive could provide for example the means to induce resonant inter-level transitions, or to perform Floquet engineering or Landau-Zener-Stückelberg state preparation. Here, we introduce polaromechanical metamaterials, two-dimensional arrays of µm-sized traps confining zero-dimensional light-matter polariton fluids and GHz phonons. A strong exciton-mediated polariton-phonon interaction induces a time-dependent inter-site polariton coupling J(t) with remarkable consequences for the dynamics. When locally perturbed by continuous wave optical excitation, a mechanical self-oscillation sets-in and polaritons respond by locking the energy detuning between neighbor sites at integer multiples of the phonon energy, evidencing asynchronous locking involving the polariton and phonon fields. These results open the path for the coherent control of dissipative quantum light fluids with hypersound in a scalable platform.

15.
Phys Rev Lett ; 109(26): 266602, 2012 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-23368596

RESUMEN

Spin dephasing via the spin-orbit interaction (SOI) is a major mechanism limiting the electron spin lifetime in III-V zincblende quantum wells (QWs). The dephasing can be suppressed in GaAs(111) quantum wells by applying an electric field. The suppression has been attributed to the compensation of the intrinsic SOI associated with the bulk inversion asymmetry of the GaAs lattice by a structural induced asymmetry SOI term induced by an electric field. We provide direct experimental evidence for this mechanism by demonstrating the transition between the bulk inversion asymmetry-dominated to a structural induced asymmetry-dominated regime via photoluminescence measurements carried out over a wide range of applied fields. Spin lifetimes exceeding 100 ns are obtained near the compensating electric field, thus making GaAs(111) QWs excellent candidates for the electrical storage and manipulation of spins.

16.
Nanotechnology ; 23(31): 315303, 2012 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-22802162

RESUMEN

Ultrahigh-frequency surface acoustic wave devices were fabricated on a ZnO/SiO2/Si substrate using step-and-flash nanoimprint lithography combined with hydrogen silsesquioxane (HSQ) planarization. Excellent critical dimension control was demonstrated for interdigital transducers with finger electrode widths from 125 down to 65 nm. Fundamental and higher-order Rayleigh modes up to 16.1 GHz were excited and detected, which is the highest frequency for ZnO-based transducers on silicon reported so far. Surface acoustic modes were confirmed with numerical simulations. Simulation results showed good agreement with the experimental data.

17.
Phys Rev Lett ; 106(21): 216602, 2011 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-21699325

RESUMEN

Magneto-optic Kerr microscopy was employed to investigate the spin-orbit interactions of electrons traveling in semiconductor quantum wells using surface acoustic waves (SAWs). Two-dimensional images of the spin flow induced by SAWs exhibit anisotropic spin precession behaviors caused by the coexistence of different types of spin-orbit interactions. The dependence of spin-orbit effective magnetic fields on SAW intensity indicates the existence of acoustically controllable spin-orbit interactions resulting from the strain and Rashba contributions induced by the SAWs.

18.
Phys Rev Lett ; 104(16): 165502, 2010 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-20482064

RESUMEN

We present the experimental observation of Bloch oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling of surface acoustic waves in perturbed grating structures on a solid substrate. A model providing a quantitative description of our experimental observations, including multiple Landau-Zener transitions of the anticrossed surface acoustic Wannier-Stark states, is developed. The use of a planar geometry for the realization of the Bloch oscillations and Landau-Zener tunneling allows a direct access to the elastic field distribution. The vertical surface displacement has been measured by interferometry.

19.
Phys Rev Lett ; 105(11): 116402, 2010 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-20867591

RESUMEN

We demonstrate that the tunable potential introduced by a surface acoustic wave on a homogeneous polariton condensate leads to fragmentation of the condensate into an array of wires which move with the acoustic velocity. Reduction of the spatial coherence of the condensate emission along the surface acoustic wave direction is attributed to the suppression of coupling between the spatially modulated condensates. Interparticle interactions observed at high polariton densities screen the acoustic potential, partially reversing its effect on spatial coherence.

20.
J Chem Phys ; 133(3): 034507, 2010 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-20649337

RESUMEN

Pump and thermally induced color tunabilities were demonstrated in Yb(3+)/Tm(3+) codoped low silica calcium aluminosilicate (LSCAS) glass under anti-Stokes excitation at 1.064 microm. The effects of pump intensity and sample's temperature on the upconversion emissions and mainly on the color tunabilities (from 800 to 480 nm) were investigated. The results revealed a 20- and a threefold reductions at 800/480 nm ratio as, respectively, the pump intensity and sample's temperature were increased from 27 to 700 kW/cm(2) and from 296 to 577 K. These behaviors with pump intensity and temperature (a strong increase of the 480 nm emission in comparison with the 800 nm one) were attributed to the several efficient processes occurring in the LSCAS system (Yb(3+)-->Tm(3+) energy-transfer processes, easy saturations of the Yb(3+) and Tm(3+) excited states, and radiative emissions). Besides these assigns, the temperature dependence is mainly assigned to the temperature-dependent effective absorption cross section of the ytterbium sensitizer through the so-called multiphonon-assisted anti-Stokes excitation process. Theoretical analyses and fits of the experimental data provided quantitative information.

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