Time-Reversed Lasing and Interferometric Control of Absorption

Wan, Wenjie; Chong, Yidong; Li, Ge; Noh, Heeso; Stone, A. Douglas; Cao, Hui

doi:10.1126/science.1200735

Cited by 749 publications

(676 citation statements)

References 24 publications

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“…Such non-Hermitian potential regions 4,5 , which serve as sources and sinks for waves, respectively, can give rise to novel wave effects that are impossible to realize with conventional, Hermitian potentials. Examples of this kind, which were meanwhile also realized in the experiment [6][7][8][9][10] , are the unidirectional invisibility of a gain-loss potential 11 , devices that can simultaneously act as laser and as a perfect absorber [12][13][14] and resonant structures with unusual features like non-reciprocal light transmission 10 or loss-induced lasing [15][16][17] . In particular, systems with a so-called parity-time (PT ) symmetry 18 , where gain and loss are carefully balanced, have recently attracted enormous interest in the context of nonHermitian photonics [19][20][21][22][23][24] .…”

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confidence: 99%

Constant-intensity waves and their modulation instability in non-Hermitian potentials

et al. 2015

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In all of the diverse areas of science where waves play an important role, one of the most fundamental solutions of the corresponding wave equation is a stationary wave with constant intensity. The most familiar example is that of a plane wave propagating in free space. In the presence of any Hermitian potential, a wave's constant intensity is, however, immediately destroyed due to scattering. Here we show that this fundamental restriction is conveniently lifted when working with non-Hermitian potentials. In particular, we present a whole class of waves that have constant intensity in the presence of linear as well as of nonlinear inhomogeneous media with gain and loss. These solutions allow us to study the fundamental phenomenon of modulation instability in an inhomogeneous environment. Our results pose a new challenge for the experiments on non-Hermitian scattering that have recently been put forward.

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confidence: 99%

Constant-intensity waves and their modulation instability in non-Hermitian potentials

et al. 2015

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“…If the material possesses the property of ε(x) = ε * (−x), the system is PT -symmetric because the system restores itself after simultaneous parity and time-reversal operations. Such systems have been extensively studied recently and a great variety of interesting phenomena have been discovered, including unusual beam dynamics within paraxial approximations [4][5][6], lasing effect [7][8][9], unidirectional transmission [10][11][12], negative refraction [13], single-particle sensors [14], and others [15][16][17][18][19][20]. Since it is not easy to achieve PT symmetry experimentally, several ways have been proposed to avoid the use of gain in a system.…”

Section: Introductionmentioning

confidence: 99%

Coalescence of exceptional points and phase diagrams for one-dimensionalPT-symmetric photonic crystals

2015

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Non-Hermitian systems with parity-time-(PT )-symmetric complex potentials can exhibit a phase transition when the degree of non-Hermiticity is increased. Two eigenstates coalesce at a transition point, which is known as the exceptional point (EP) for a discrete spectrum and spectral singularity for a continuous spectrum. The existence of an EP is known to give rise to a great variety of novel behaviors in various fields of physics. In this work, we study the complex band structures of one-dimensional photonic crystals with PT -symmetric complex potentials by setting up a Hamiltonian using the Bloch states of the photonic crystal without loss or gain as a basis. As a function of the degree of non-Hermiticity, two types of PT symmetry transitions are found. One is that a PT -broken phase can reenter into a PT -exact phase at a higher degree of non-Hermiticity. The other is that two EPs, one originating from the Brillouin zone center and the other from the Brillouin zone boundary, can coalesce at some k point in the interior of the Brillouin zone and create a singularity of higher order. Furthermore, we can induce a band inversion by tuning the filling ratio of the photonic crystal, and we find that the geometric phases of the bands before and after the inversion are independent of the amount of non-Hermiticity as long as the PT -exact phase is not broken. The standard concept of topological transition can hence be extended to non-Hermitian systems.

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“…A simple experimental demonstration of a slab CPA was realized using a silicon wafer [20]. CPA resonances were observed in the 1000 nm wavelength range, with measured output intensities showing strong dependence on the relative phase of the two input beams.…”

Section: Planar Structures Dielectric Slabsmentioning

confidence: 99%

“…A coherent perfect absorber (CPA) [7] generalizes this phenomenon to arbitrary incoming waveforms that can consist of two or more waves, such as waves incident on opposite faces of an open slab or film [7,20,21]. To achieve perfect absorption, it is essential to appropriately choose the values of the system parameters, the operating wavelength and the input waveform, including the intensities and relative phases of the input beams.…”

Section: Introductionmentioning

confidence: 99%

Coherent perfect absorbers: linear control of light with light

et al. 2017

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Absorption of electromagnetic energy by a material is a phenomenon that underlies many applied problems, including molecular sensing, photocurrent generation and photodetection. Commonly, the incident energy is delivered to the system through a single channel, for example by a plane wave incident on one side of an absorber. However, absorption can be made much more efficient by exploiting wave interference. A coherent perfect absorber is a system in which complete absorption of electromagnetic radiation is achieved by controlling the interference of multiple incident waves. Here, we review recent advances in the design and applications of such devices. We present the theoretical principles underlying the phenomenon of coherent perfect absorption and give an overview of the photonic structures in which it can be realized, including planar and guidedmode structures, graphene-based systems, parity-and time-symmetric structures, 3D structures and quantum-mechanical systems. We then discuss possible applications of coherent perfect absorption in nanophotonics and, finally, we survey the perspectives for the future of this field.

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Time-Reversed Lasing and Interferometric Control of Absorption

Cited by 749 publications

References 24 publications

Constant-intensity waves and their modulation instability in non-Hermitian potentials

Constant-intensity waves and their modulation instability in non-Hermitian potentials

Coalescence of exceptional points and phase diagrams for one-dimensionalPT-symmetric photonic crystals

Coherent perfect absorbers: linear control of light with light

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