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1.
Zhongguo Dang Dai Er Ke Za Zhi ; 21(6): 541-546, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31208506

RESUMO

OBJECTIVE: To study the value of fast spin-echo diffusion weighted imaging (TSE-DWI) apparent diffusion coefficient (ADC) in children aged 2-12 years with intellectual disability (ID)/global developmental delay (GDD) who have normal conventional brain MRI findings. METHODS: A total of 578 children with normal conventional brain MRI findings who met the diagnostic criteria for ID/GDD and 375 normal children were enrolled. Their imaging and clinical data were collected. All children underwent scanning with brain TSE-DWI sequence and routine sequence. ADC values of each brain region were compared between normal children with different ages, as well as between children with different degrees of ID/GDD in each age group. The influence of Adaptive Behavior Assessment System-II (ABAS-II) score on ADC values of each brain region was analyzed. RESULTS: For the normal children, the ADC values of the frontal and temporal white matter, the corpus callosum, the inner capsule, the centrum semiovale, the cerebellar dentate nucleus, the optic radiation, the thalamus, the lenticular nucleus, and the caudate nucleus gradually decreased with age (P<0.05). ADC values of the deep white matter, the shallow white matter, the deep gray matter nuclei, and the shallow gray matter increased with the increase in the degree of ID/GDD in the ID/GDD children aged 4-6 years (P<0.05). In the children with ID/GDD, the ADC values of the deep white matter, the shallow white matter, and the deep gray matter nuclei decreased with age (P<0.05). The ADC values of the children with ID/GDD decreased with the increase in ABAS-II score (P<0.05). CONCLUSIONS: ADC can reflect the subtle structural changes of brain regions in children with ID/GDD who have normal conventional brain MRI findings. It may be associated with social adaptation. It can provide an objective basis for the quantitative diagnosis of ID/GDD in children.


Assuntos
Deficiência Intelectual , Substância Branca , Encéfalo , Criança , Pré-Escolar , Imagem de Difusão por Ressonância Magnética , Humanos , Deficiência Intelectual/diagnóstico por imagem , Imagem por Ressonância Magnética
2.
Opt Express ; 27(5): 6660-6671, 2019 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-30876246

RESUMO

Cavity-enhanced optical controlling is experimentally observed with a low-control laser power in a cavity-atom ensemble system. Here, the three-level atoms are coupled with two optical modes of a Fabry-Perot cavity, where a new theoretical model is developed to describe the effective three-wave mixing process between spin-wave and optical modes. By adjusting either temperature or cavity length, we demonstrate the precise frequency tuning of the hybrid optical-atomic resonances. When the doubly-resonant condition is satisfied, the probe laser can be easily modulated by a control laser. In addition, interesting non-Hermitian physics are predicted theoretically and demonstrated experimentally, and all-optical switching is also achieved. Such a doubly-resonant cavity-atom ensemble system without a specially designed cavity can be used for future applications, such as optical signal storage and microwave-to-optical frequency conversion.

3.
Opt Lett ; 44(5): 1150-1153, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30821735

RESUMO

To extend the coherence of quantum transitions for laser locking, as well as increase the compactness and stability of the experimental setup, we propose to utilize photonic integrated resonators with high second-harmonic (SH) generation efficiencies as reliable frequency doublers that link the desired frequencies with the frequency references. In this Letter, a sufficiently strong SH signal up to microwatts was generated by a photonic integrated frequency doubler using a milliwatt infrared (IR) laser source. Furthermore, an increased SH generation bandwidth covering Rb85 and Rb87D2 transition lines, as well as saturated absorption spectroscopy, was demonstrated by tuning the pump power and chip temperature. Here we present, to the best of our knowledge, the first successful locking of an IR laser to Rb saturated absorption lines via a photonic chip frequency doubler.

4.
Opt Express ; 26(21): 27294-27304, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-30469800

RESUMO

Third-harmonic generation can be realized via both χ(3) and cascaded χ(2) nonlinear processes in a triply-resonant microcavity. It is still unknown how these processes interfere with each other and the optimization of the conversion efficiency still remains as a question. In this work, the interplay between the direct third-harmonic generation and the cascaded process combining of the second-harmonic generation and the sum-frequency generation are investigated. It is found that the interference effect between these two processes can be used to improve the conversion efficiency. By optimizing the cavity resonance and the external coupling conditions, the saturation of the nonlinear conversion is mitigated and the third-harmonic conversion efficiency is increased. A design rule is provided for achieving efficient third-harmonic generation in an optical microcavity, which can be generalized further to the high-order harmonic generations.

5.
Nat Commun ; 9(1): 1797, 2018 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-29728619

RESUMO

Non-reciprocal devices, which allow non-reciprocal signal routing, serve as fundamental elements in photonic and microwave circuits and are crucial in both classical and quantum information processing. The radiation-pressure-induced coupling between light and mechanical motion in travelling-wave resonators has been exploited to break the Lorentz reciprocity, enabling non-reciprocal devices without magnetic materials. Here, we experimentally demonstrate a reconfigurable non-reciprocal device with alternative functions as either a circulator or a directional amplifier via optomechanically induced coherent photon-phonon conversion or gain. The demonstrated device exhibits considerable flexibility and offers exciting opportunities for combining reconfigurability, non-reciprocity and active properties in single photonic devices, which can also be generalized to microwave and acoustic circuits.

6.
Opt Express ; 25(14): 16879-16887, 2017 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-28789187

RESUMO

A tunable Raman laser in the hollow bottle-like microresonator is demonstrated. By controlling the pump laser frequency, we have demonstrated continuous Raman laser frequency tuning. We also have studied the interesting transient mode evolution with Raman gain by sweeping the pump and probe laser, and verified the thermal tuning mechanism by theoretical simulations. By mechanically stretching the resonator, we have achieved the large range frequency tuning of the Raman laser, with the tuning range of 132 GHz with the resolution about 85 MHz. The demonstrated tunable Raman laser can be used as a source for future optical applications.

7.
Opt Express ; 25(4): 4046-4053, 2017 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-28241612

RESUMO

In this paper, we report the mechanical tuning of the optical and mechanical modes in the hollow bottle-like microresonator (BLMR). The optical modes with a quality factor of 1.55 × 108 and mechanical modes with a quality factor of 2.5 × 103 were demonstrated in such microresonators. By stretching the microresonator, the optical modes can be tuned over one free spectral range, as large as 917 GHz (~ 7.3 nm). Meanwhile, the range of frequency tuning of mechanical modes can be as large as 1 MHz, which is about 2.9% of the mode frequency. This effective approach to tune the optomechanical cavity can be used for the tunable photon-phonon conversion and the synchronization of mechanical oscillators in separated optomechanical systems.

8.
Phys Rev Lett ; 118(3): 033901, 2017 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-28157372

RESUMO

Chirality is an asymmetric property widely found in nature. Here, we propose and demonstrate experimentally the spontaneous emergence of chirality in an on-chip ultrahigh-Q whispering-gallery microresonator, without broken parity or time-reversal symmetry. This counterintuitive effect arises due to the inherent Kerr-nonlinearity-modulated coupling between clockwise and counterclockwise propagating waves. Above an input threshold of a few hundred microwatts, the initial chiral symmetry is broken spontaneously, and the counterpropagating output ratio exceeds 20∶1 with bidirectional inputs. The spontaneous chirality in an on-chip microresonator holds great potential in studies of fundamental physics and applied photonic devices.

9.
Opt Lett ; 41(6): 1249-52, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26977681

RESUMO

We have studied the Kerr effect in silica microspheres and demonstrated compensation of the Kerr effect for transient optomechanically induced transparency (OMIT). Due to the Kerr effect of the temporal strong driving pulse, an asymmetric transparency dip is observed during the transient OMIT experiment when the laser frequency is locked at one mechanical frequency, ω(m), below the whispering gallery mode resonance using a weak locking pulse. For compensation of the Kerr effect, we lock the laser at a lower frequency and show the symmetric transparency window. These results are important for studying photon-phonon interconversion, especially in systems with strong driving power.

10.
Sci Adv ; 1(8): e1500257, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26601256

RESUMO

A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons are signal carriers with high transport speed and parallel processing capability. Besides the most frequently demonstrated silicon-based circuits, PICs require a variety of materials for light generation, processing, modulation, and detection. With their diversity and flexibility, organic molecular materials provide an alternative platform for photonics; however, the versatile fabrication of organic integrated circuits with the desired photonic performance remains a big challenge. The rapid development of flexible electronics has shown that a solution printing technique has considerable potential for the large-scale fabrication and integration of microsized/nanosized devices. We propose the idea of soft photonics and demonstrate the function-directed fabrication of high-quality organic photonic devices and circuits. We prepared size-tunable and reproducible polymer microring resonators on a wafer-scale transparent and flexible chip using a solution printing technique. The printed optical resonator showed a quality (Q) factor higher than 4 × 10(5), which is comparable to that of silicon-based resonators. The high material compatibility of this printed photonic chip enabled us to realize low-threshold microlasers by doping organic functional molecules into a typical photonic device. On an identical chip, this construction strategy allowed us to design a complex assembly of one-dimensional waveguide and resonator components for light signal filtering and optical storage toward the large-scale on-chip integration of microscopic photonic units. Thus, we have developed a scheme for soft photonic integration that may motivate further studies on organic photonic materials and devices.

11.
Opt Express ; 23(19): 25118-27, 2015 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-26406711

RESUMO

We propose a new approach to realize all-optical circulator based on stimulated Brillouin scattering in an integrated microresonator. Stimulated Brillouin scattering is a basic interaction between photon and traveling acoustic wave resulted from electrostriction and photoelastic effects. Due to the phase-matching requirement, the circulating acoustic wave can only couple to probe light which propagating along or opposite to the pump laser direction, thus exhibits a non-reciprocal phase shift. Combined with Mach-Zehnder interferometer, the optical circulator can be realized. Though the bandwidth is relatively small because of the narrow-band nature of microresonator, this magnetic-free all-optical integrated circulator may be applied for future on-chip photonic information processing.

12.
Int J Clin Exp Med ; 8(7): 11490-5, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26379968

RESUMO

OBJECTIVE: To analyze the distribution of HLA-DRB1 and HLA-DQB1 alleles and its correlation with IFN-γ, IL-2, IL-6, IL-10 in HPV16 infected women with advanced cervical carcinoma. METHODS: We collected 137 blood samples of cervical carcinoma patients diagnosed by pathology as cervical cancer in stage IIb-IVb before the treatment, and we gathered 175 blood samples of healthy women living in the local. We determined the genetic subtypes of HLA-DRB1 and HLA-DQB1, and we measured the concentration of IFN-γ, IL-2, IL-6 and IL-10. We compared the difference of cytokines in patients with different clinical stages and the healthy in the control group. According to genetic subtypes of HLA-DRB1 and HLA-DQB1, we also compared the concentration of cytokine (CK) in different genetic subtypes. RESULTS: Eight HLA-DRB1 alleles and four HLA-DQB1 alleles were found. There were not significant differences between each allele in the concentration of IFN-γ, IL-2, IL-6, and IL-10. CONCLUSION: HLA-DRB1*07, HLA-DQB1*02 and HLA-DQB1*03 were the differentially expressed gene in HPV16 infected patients with advanced cervical cancer. There may be correlations between the occurrence, development of cervical cancer and IFN-γ, IL-2, IL-6, IL-10.

13.
Nat Commun ; 6: 6193, 2015 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-25648234

RESUMO

Stimulated Brillouin scattering is a fundamental interaction between light and travelling acoustic waves and arises primarily from electrostriction and photoelastic effects, with an interaction strength several orders of magnitude greater than that of other relevant non-linear optical processes. Here we report an experimental demonstration of Brillouin-scattering-induced transparency in a high-quality whispering-gallery-mode optical microresonantor. The triply resonant Stimulated Brillouin scattering process underlying the Brillouin-scattering-induced transparency greatly enhances the light-acoustic interaction, enabling the storage of light as a coherent, circulating acoustic wave with a lifetime up to 10 µs. Furthermore, because of the phase-matching requirement, a circulating acoustic wave can only couple to light with a given propagation direction, leading to non-reciprocal light storage and retrieval. These unique features establish a new avenue towards integrated all-optical switching with low-power consumption, optical isolators and circulators.

14.
J Am Chem Soc ; 135(35): 12928-31, 2013 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-23930931

RESUMO

Colloidosomes are usually produced from a series of building blocks with different sizes ranging from several nanometers to micrometers or various shapes, such as particles, microrods, and quantum dots. Colloidosomes can possess a variety of characteristics in terms of photics, electrology, mechanical strength, and selective permeability, derived from their building blocks. However, poor mechanical stability and complicated synthesis processes have limited the applications of colloidosomes. Here, we report a new one-pot colloidal chemistry route to synthesize phenol formaldehyde resin (PFR), Ag@PFR, and Au@PFR colloidosomes with high yields. The method can be modified to synthesize different kinds of doped colloidosomes with different components, which will provide a new approach to design colloidosomes with different functions.

15.
Appl Opt ; 52(2): 298-301, 2013 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-23314648

RESUMO

High-Q deformed silica microsphere cavities are fabricated by short CO(2) laser pulses, where the deformation is well controlled by adjusting the intensity and number of pulses. Using this method, directional emission from whispering-gallery mode (WGM) with a high quality factor of 10(7) in these microspheres is achieved, and a transition from two-directional to single-directional emission is observed. Such concentrated directional emission and high-Q of WGMs show high potential for future studies of the chaotic ray dynamics in deformed microcavity and cavity quantum electrodynamics and optomechanics.

16.
Ying Yong Sheng Tai Xue Bao ; 24(11): 3162-8, 2013 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-24564145

RESUMO

Taking a large standard runoff plot on a red soil slope in Qiyang County, southern Hunan Province as a case, this paper studied the surface soil phosphorus loss characteristics in the hilly red soil regions of southern Hunan under eight ecological planting patterns. The phosphorus loss from wasteland (T1) was most serious, followed by that from natural sloped cropping patterns (T2 and T3), while the phosphorus loss amount from terrace cropping patterns (T4-T8) was the least, only occupying 9.9%, 37%, 0.7%, 2.3%, and 1.9% of T1, respectively. The ecological planting patterns directly affected the forms of surface-lost soil phosphorus, with the particulate phosphorus (PP) as the main lost form. Under the condition of rainstorm (daily rainfall > 50 mm), rainfall had lesser effects on the phosphorus loss among different planting patterns. However, the phosphorus loss increased with increasing rain intensity. The surface soil phosphorus loss mainly occurred from June to September. Both the rainfall and the rain intensity were the factors directly affected the time distribution of surface soil phosphorus loss in hilly red soil regions of southern Hunan.


Assuntos
Conservação dos Recursos Naturais/métodos , Produtos Agrícolas/crescimento & desenvolvimento , Ecossistema , Fósforo/análise , Solo/química , Agricultura/métodos , China , Sedimentos Geológicos/análise , Chuva , Movimentos da Água
18.
Opt Lett ; 35(20): 3393-5, 2010 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-20967077

RESUMO

Passive decoy state quantum key distribution (QKD) has enormous potential in high-speed applications. In this Letter, an intrinsic-stable non-Poissonian light source was implemented with Faraday mirrors and could be a crucial element in realizing passive decoy state QKD. The stable g((2))(0) was obtained through a Hanbury Brown-Twiss experiment, and the results fit well with the theoretical value according to Curty et al.'s theory [Opt. Lett.34, 3238 (2009)].

19.
Opt Express ; 18(6): 6340-6, 2010 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-20389657

RESUMO

CdSe/ZnS colloidal quantum dots generally exist as blinking phenomena during the luminescence process that remarkably influences its applications. In this work, we used the surface plasmonic effect to effectively modulate single quantum dots. Obvious contrasts have been observed by comparing single quantum dots on silica and gold films. The surface plasmon is shown to obviously suppress the blinking of single quantum dots. With further demonstrated second- order correlation measurements, an anti-bunching effect was observed. The anti-bunching dip gives the smallest value of g(2)(0) = 0.15, and the lifetime of the exciton has been reduced. This method presents the application's potential towards tunable high-emitting-speed single photon sources at room temperature.


Assuntos
Compostos de Cádmio/química , Medições Luminescentes/instrumentação , Pontos Quânticos , Compostos de Selênio/química , Sulfetos/química , Ressonância de Plasmônio de Superfície/instrumentação , Compostos de Zinco/química , Desenho de Equipamento , Análise de Falha de Equipamento
20.
Phys Rev Lett ; 105(15): 153902, 2010 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-21230906

RESUMO

We propose a kind of plasmonic whispering-gallery mode highly localized on the exterior surface of a metal-coated microresonator. This exterior (EX) surface mode possesses high quality factors at room temperature, and can be efficiently excited by a tapered fiber. The EX mode can couple to an interior (IN) mode and this coupling produces a strong anticrossing behavior, which not only allows conversion of IN to EX modes, but also forms a long-lived antisymmetric mode. As a potential application, the EX mode could be used for a biosensor with a sensitivity high of up to 500 nm per refraction index unit, a large figure of merit, and a wide detection range.

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