Showing papers by "Lan Yang published in 2015"
TL;DR: This work studies OMIT in parity-time (PT)-symmetric microresonators with a tunable gain-to-loss ratio and shows that by tuning the pump power at a fixed gain- to- Loss ratio, one can switch from slow to fast light and vice versa.
Abstract: Optomechanically-induced transparency (OMIT) and the associated slowing of light provide the basis for storing photons in nanoscale devices. Here we study OMIT in parity-time (PT)-symmetric microresonators with a tunable gain-to-loss ratio. This system features a sideband-reversed, non-amplifying transparency , i.e., an inverted-OMIT. When the gain-to-loss ratio is varied, the system exhibits a transition from a PT-symmetric phase to a broken-PT-symmetric phase. This PT-phase transition results in the reversal of the pump and gain dependence of the transmission rates. Moreover, we show that by tuning the pump power at a fixed gain-to-loss ratio, or the gain-to-loss ratio at a fixed pump power, one can switch from slow to fast light and vice versa. These findings provide new tools for controlling light propagation using nanofabricated phononic devices.
251 citations
TL;DR: In this article, the authors presented a general mechanism to amplify nonlinearity using parity-time symmetric structures, and showed that an on-chip microscale phonon diode can be fabricated using a π-mathcal{PT}$-symmetric mechanical system.
Abstract: Nonreciprocal devices that permit wave transmission in only one direction are indispensible in many fields of science including, e.g., electronics, optics, acoustics, and thermodynamics. Manipulating phonons using such nonreciprocal devices may have a range of applications such as phonon diodes, transistors, switches, etc. One way of achieving nonreciprocal phononic devices is to use materials with strong nonlinear response to phonons. However, it is not easy to obtain the required strong mechanical nonlinearity, especially for few-phonon situations. Here we present a general mechanism to amplify nonlinearity using parity-time ($\mathcal{PT}$)-symmetric structures, and show that an on-chip microscale phonon diode can be fabricated using a $\mathcal{PT}$-symmetric mechanical system, in which a lossy mechanical resonator with very weak mechanical nonlinearity is coupled to a mechanical resonator with mechanical gain but no mechanical nonlinearity. When this coupled system transits from the $\mathcal{PT}$-symmetric regime to the broken-$\mathcal{PT}$-symmetric regime, the mechanical nonlinearity is transferred from the lossy resonator to the one with gain, and the effective nonlinearity of the system is significantly enhanced. This enhanced mechanical nonlinearity is almost lossless because of the gain-loss balance induced by the $\mathcal{PT}$-symmetric structure. Such an enhanced lossless mechanical nonlinearity is then used to control the direction of phonon propagation, and can greatly decrease (by over three orders of magnitude) the threshold of the input-field intensity necessary to observe the unidirectional phonon transport. We propose an experimentally realizable lossless low-threshold phonon diode of this type. Our study opens up perspectives for constructing on-chip few-phonon devices and hybrid phonon-photon components.
119 citations
TL;DR: This work proposes a coherent optical amplification technique to compensate losses in metamaterials, based on a novel plasmon injection (PI or Π) scheme, and opens the possibility of reviving the early dreams of making "magical" metamMaterials from scratch.
Abstract: Metamaterials have introduced a whole new world of unusual materials with functionalities that cannot be attained in naturally occurring material systems by mimicking and controlling the natural phenomena at subwavelength scales. However, the inherent absorption losses pose a fundamental challenge to the most fascinating applications of metamaterials. Based on a novel plasmon injection (PI or Π) scheme, we propose a coherent optical amplification technique to compensate losses in metamaterials. Although the proof of concept device here operates under normal incidence only, our proposed scheme can be generalized to an arbitrary form of incident waves. The Π scheme is fundamentally different from major optical amplification schemes. It does not require a gain medium, interaction with phonons, or any nonlinear medium. The Π scheme allows for loss-free metamaterials. It is ideally suited for mitigating losses in metamaterials operating in the visible spectrum and is scalable to other optical frequencies. These findings open the possibility of reviving the early dreams of making "magical" metamaterials from scratch.
54 citations
TL;DR: A new class of nanocouplers based on cavity enhanced Rayleigh scattering from nano-scatterer(s) on resonator surface is reported and demonstrated, which will not only expand the range of applications enabled by WGMRs, but also provide a possible route to integrate them into solar powered green photonics.
Abstract: Whispering gallery mode resonators (WGMRs) take advantage of strong light confinement and long photon lifetime for applications in sensing, optomechanics, microlasers and quantum optics. However, their rotational symmetry and low radiation loss impede energy exchange between WGMs and the surrounding. As a result, free-space coupling of light into and from WGMRs is very challenging. In previous schemes, resonators are intentionally deformed to break circular symmetry to enable free-space coupling of carefully aligned focused light, which comes with bulky size and alignment issues that hinder the realization of compact WGMR applications. Here, we report a new class of nanocouplers based on cavity enhanced Rayleigh scattering from nano-scatterer(s) on resonator surface, and demonstrate whispering gallery microlaser by free-space optical pumping of an Ytterbium doped silica microtoroid via the scatterers. This new scheme will not only expand the range of applications enabled by WGMRs, but also provide a possible route to integrate them into solar powered green photonics.
46 citations
TL;DR: Hybrid wishpering-gallery-mode resonators were made by depositing a ploycrystalline lihtiiim noibate film onto silica resonators to achieve efficient coupling with tapered fiber and all-optical modulation.
Abstract: Lithium-niobate-silica hybrid resonators with quality factors higher than 10(5) are fabricated by depositing a layer of polycrystalline lithium niobate on the flat top surfaces of inverted-wedge silica microdisk resonators. All-optical modulation with improved performance over silica-only resonators and electro-optic modulation not achievable in silica-only resonators are realized in the hybrid resonators.
38 citations
TL;DR: In this article, a metamaterial is used to distill highly entangled states from less entangled states, which is known as entanglement distillation, using a quantum state filtering method.
Abstract: Plasmonics is a rapidly emerging platform for quantum state engineering with the potential for building ultra-compact and hybrid optoelectronic devices. Recent experiments have shown that despite the presence of decoherence and loss, photon statistics and entanglement can be preserved in single plasmonic systems. This preserving ability should carry over to plasmonic metamaterials, whose properties are the result of many individual plasmonic systems acting collectively, and can be used to engineer optical states of light. Here, we report an experimental demonstration of quantum state filtering, also known as entanglement distillation, using a metamaterial. We show that the metamaterial can be used to distill highly entangled states from less entangled states. As the metamaterial can be integrated with other optical components this work opens up the intriguing possibility of incorporating plasmonic metamaterials in on-chip quantum state engineering tasks.
32 citations
TL;DR: This work opens up new directions in quantum optical state engineering by showing how metamaterials can be used to carry out a quantum information processing task.
Abstract: We propose a scheme for the distillation of partially entangled two-photon Bell and three-photon W states using metamaterials. The distillation of partially entangled Bell states is achieved by using two metamaterials with polarization dependence, one of which is rotated by π/2 around the direction of propagation of the photons. On the other hand, the distillation of three-photon W states is achieved by using one polarization dependent metamaterial and two polarization independent metamaterials. Upon transmission of the photons of the partially entangled states through the metamaterials the entanglement of the states increases and they become distilled. This work opens up new directions in quantum optical state engineering by showing how metamaterials can be used to carry out a quantum information processing task.
27 citations
TL;DR: This work proposes and experimentally demonstrate that by utilizing Raman gain one can achieve on-demand control of the coupling regime without any mechanical movement in the resonator system, and shows that with the help of Raman Gain control, the transitions between various coupling regimes can affect the light transmission spectra so as to provide better resolvability and signal amplification.
Abstract: Waveguide-coupled optical resonators have played an important role in a wide range of applications including optical communication, sensing, nonlinear optics, slow/fast light, and cavity QED. In such a system, the coupling regimes strongly affect the resonance feature in the light transmission spectra, and hence the performance and outcomes of the applications. Therefore it is crucial to control the coupling between the waveguide and the microresonator. In this work, we investigated a fiber-taper coupled whispering-gallery-mode microresonator system, in which the coupling regime is traditionally controlled by adjusting the distance between the resonator and the fiber-taper mechanically. We propose and experimentally demonstrate that by utilizing Raman gain one can achieve on-demand control of the coupling regime without any mechanical movement in the resonator system. Particularly, the application of Raman gain is accompanied by Q enhancement. We also show that with the help of Raman gain control, the transitions between various coupling regimes can affect the light transmission spectra so as to provide better resolvability and signal amplification. This all-optical approach is also suitable for monolithically integrated and packaged waveguide-resonator systems, whose coupling regime is fixed at the time of manufacturing. It provides an effective route to control the light transmission in a waveguide-couple resonator system without mechanically moving individual optical components.
21 citations
TL;DR: In this paper, a transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically, which can sense coupling region, external linear variation together with the speed and the size of a nanoparticle.
Abstract: A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically. There are two ways to realize the transient sensor: monitor the spectrum by fast scanning of probe laser frequency or monitor the transmitted light with fixed laser frequency. For both methods, the non-equilibrium response not only tells the ultrafast environment variance, but also enable higher sensitivity. As examples of application, the transient sensor for nanoparticles adhering and passing by the microcavity is studied. It's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle. We believe that our researches will open a door to the fast dynamic sensing by microcavity.
19 citations
TL;DR: A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically and it's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle.
Abstract: A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically. There are two ways to realize the transient sensor: monitor the spectrum by fast scanning of probe laser frequency or monitor the transmitted light with fixed laser frequency. For both methods, the non-equilibrium response not only tells the ultrafast environment variance, but also enable higher sensitivity. As examples of application, the transient sensor for nanoparticles adhering and passing by the microcavity is studied. It's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle. We believe that our researches will open a door to the fast dynamic sensing by microcavity.
16 citations
Patent•
13 Apr 2015TL;DR: In this article, a method and system for optical systems based on parity-time symmetry and its breaking, and for non-reciprocal light transmission in a parity time symmetric micro-resonator system are provided.
Abstract: A method and system for optical systems based on parity-time symmetry and its breaking, and for nonreciprocal light transmission in a parity-time symmetric micro-resonator system are provided. The system includes an optical assembly that includes a first dissipative optical system and a second optical system coupled in energy transfer communication with the first optical system. The second optical system is configured to receive a continuous flow of energy from an external source and to transfer energy to the first optical system through the couple wherein the energy transferred to the first optical system from the second optical system is approximately equal to the energy dissipated in the first optical system, where the energy transferred to the first optical system from the second optical system is selectable using at least one of an amount of couple between the first optical system and the second optical system and a gain of the second optical system.
Patent•
16 Mar 2015
TL;DR: In this article, a micro-laser based nano-scale object detection system and method using frequency shift and/or mode splitting techniques using a self-referenced and self-heterodyned whispering gallery Raman microlaser.
Abstract: A system and method for is a micro-laser based nano-scale object detection system and method using frequency shift and/or mode splitting techniques. The system and method can provide highly sensitive detection of nanoparticles with a self-referenced and self-heterodyned whispering-gallery Raman micro-laser. The system and method also provides for nano-particle size measurement.
24 Aug 2015
TL;DR: In this paper, a hybrid wish-gallery-mode resonator was made by depositing a ploycrystalline lihtiiim noibate film onto silica resonators, and efficient coupling with tapered fiber and all-optical modulation were realized in these resonators.
Abstract: Hybrid wishpering-gallery-mode resonators were made by depositing a ploycrystalline lihtiiim noibate film onto silica resonators. Efficient coupling with tapered fiber and all-optical modulation were realized in these resonators.
TL;DR: The formation of a photonic molecule is reported by vertically coupling two microdisk resonators using a theoretical model based on coupled mode theory and shows that mode splitting monotonously increases when one resonator vertically approaches the other.
Abstract: We report the formation of a photonic molecule by vertically coupling two microdisk resonators. We show that mode splitting monotonously increases when one resonator vertically approaches the other. However, when the vertical distance is kept fixed and one resonator is moved horizontally with respect to the other, the strength of coupling and hence the mode splitting demonstrate an oscillatory behavior. This is attributed to the interference of light coupled into the resonators through multiple coupling regions as confirmed by a theoretical model based on coupled mode theory.
10 May 2015
TL;DR: In this paper, an entanglement distillation protocol on pure and mixed states using optical metamaterials composed of gold nano-antennas and measuring the density matrices by quantum-state tomography is presented.
Abstract: We perform an entanglement distillation protocol on pure and mixed states using optical metamaterials composed of gold nano-antennas and measure the density matrices by quantum-state tomography. The fidelity is improved from 0.85 to 0.97.
TL;DR: In this article, the idea of using micro-resonators to enhance single-particle detection and identification by monitoring the Raman scattering from a particle adhered to a silica micro-sphere was explored.
Abstract: High-quality whispering-gallery-mode optical resonators have garnered interest in particle sensing for a variety of applications Here, we further explore the idea of using microresonators to enhance single-particle detection and identification by monitoring the Raman scattering from a particle adhered to a silica micro-sphere A tunable diode laser is critically coupled into a resonant mode of the micro-sphere resonator, allowing circulating power to build up within the cavity for enhanced interaction with the attached particle Experimental results of single particle Raman scattering in microsphere resonators are presented