<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="script">PT</mml:mi></mml:math>
 symmetry breaking in multilayers with resonant loss and gain locks light propagation direction

Novitsky, Denis V.; Karabchevsky, Alina; Lavrinenko, Andrei V.; Shalin, Alexander S.; Novitsky, Andrey

doi:10.1103/physrevb.98.125102

Cited by 67 publications

(33 citation statements)

References 45 publications

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“…There is a good agreement between the TD and TM methods at low ε ′′ (first region), including the position of EP (2) corresponding to the condition of a unidirectional reflectionlessness [14]. Between the exceptional points EP (1) and EP (2) (second region), there is a divergence between the results given by the TD and TM methods, in accordance with the previous observations [31]. Both reflectances and transmittance are larger for the TM approach.…”

Section: B Time-domain Simulationssupporting

confidence: 87%

“…In particular, the exceptional points obtained using the scattering matrixŜ 1 are in good correspondence to the lasing onset associated to breaking the loss-gain balance in PT -symmetric structures [14]. This feature was used to predict the properties of the systems acting simultaneously as a laser and coherent perfect absorber [24,29,30], as well as to study the lasinglike nonstationary behavior above theŜ 1 exceptional point [31]. Nevertheless, the matrixŜ 1 is rarely exploited in comparison tô S 2 .…”

Section: Problem Of the Scattering Matrix Uniquenessmentioning

confidence: 99%

“…So, the PT symmetry breaking viâ S 1 may occur near poles of the reflection and transmission coefficients and can be used as a predictor of lasing as discussed in Refs. [14,24,31].…”

Section: A General Remarksmentioning

confidence: 99%

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Unambiguous scattering matrix for non-Hermitian systems

et al. 2020

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PT symmetry is a unique platform for light manipulation and versatile use in unidirectional invisibility, lasing, sensing, etc. Broken and unbroken PT -symmetric states in non-Hermitian open systems are described by scattering matrices. A multilayer structure, as a simplest example of the open system, has no certain definition of the scattering matrix, since the output ports can be permuted. The uncertainty in definition of the exceptional points bordering PT -symmetric and PT -symmetry-broken states poses an important problem, because the exceptional points are indispensable in applications as sensing and mode discrimination. Here we derive the proper scattering matrix from the unambiguous relation between the PT -symmetric Hamiltonian and scattering matrix. We reveal that the exceptional points of the scattering matrix with permuted output ports are not related to the PT symmetry breaking. Nevertheless, they can be employed for finding a lasing onset as demonstrated in our time-domain calculations and scattering-matrix pole analysis. Our results are important for various applications of the non-Hermitian systems including encircling exceptional points, coherent perfect absorption, PT -symmetric plasmonics, etc.

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Section: B Time-domain Simulationssupporting

confidence: 87%

Section: Problem Of the Scattering Matrix Uniquenessmentioning

confidence: 99%

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Unambiguous scattering matrix for non-Hermitian systems

et al. 2020

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“…Consequently, the photometric index luminance contains information of not only light intensity but also light direction. Generally, the luminous flux of light source and reflection surface is likely to change in different directions [9], [10]. In the assessment of lighting environment or light source, direction information of luminous flux is missing with the description by the photometric index illuminance.…”

Section: Introductionmentioning

confidence: 99%

A Better Photometric Index of Photo-Biological Effect on Visual Function of Human Eye: Illuminance or Luminance?

et al. 2019

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The illuminance index has been widely used in the field of photometry, although the luminance contains more information on not only light intensity but also light direction. In this study, we clarify which photometric index is more competent to describe the influence of lighting environment on human eye. In this study, we propose a novel methodology to investigate the photo-biological effect of the lighting environment by human factor experiment. With the human factor experiments performed on 20 participants, we compare the variations of ocular responses during the Landolt-rings-counting visual task in lighting environments with similar illuminance while distinct luminance changes. With the same Correlated Color Temperature (CCT) and Spectral Power Distribution (SPD), optical performances with similar illuminance values present quite different influences on ocular responses, and the response variations are found to vary with luminance values. It is implied that the regularity of luminance influence on the ocular responses to lighting environment is likely to be dependent on luminance value instead of illuminance, and the photometric index luminance seems more appropriate to be used to assess the lighting quality in standards. INDEX TERMS Lighting environment, light direction, ocular response, luminance value, photometric index.

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“…In the field of optics, non-Hermitian is usually achieved by introducing controllable loss and gain into a system, such as a particular case, PT symmetric system, in which the loss and gain are balanced [6][7][8]. One can observe many intriguing light wave dynamics, like unidirectional propagation [9][10][11], PT symmetric laser [12,13] and photonic zero mode [14,15]. On the other hand, group velocity controlling, an important technique in the field of slow and fast light, has been a focus for many years [16,17].…”

Section: Introductionmentioning

confidence: 99%

Hermiticity-tunable beam reshaping: localization, recurrence and group velocity oscillation

Liu

Dai

et al. 2019

New J. Phys.

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We propose a novel method to reshape the light beam in a Hermiticity-tunable photonic lattice with PT symmetric perturbations. By adjusting the PT perturbations, the Hermiticity of the system varies alternatively, further resulting in the periodic oscillations of the group velocity (v g ) as well as the group velocity dispersion (GVD). Once the values of v g and its corresponding GVD recover and the averaged group velocity (v ḡ ) is zero, the light beam will be localized and recur at these Hermitian points. Further study indicates that GVD plays a key role in the evolution of the light beam, larger positive dispersion [Re(GVD)] and lower magnitude of Im(GVD) lead to higher peak energy of the light field. Our work provides a non-resonant way to control the light propagation and to reshape the group velocity distribution, which may have promising applications in all-optical circuit, optical sensor and optical communications.We propose a type of Hermitian-tunable photonic lattice with perturbation of PT symmetry. Such perturbations will introduce an imaginary phase factor Φ into the coupling constant. In consequence, the dispersion relations of such a system is Φ dependent and the Hermiticity of such a system will be tunable. Further study indicates that the perturbation will result in the oscillations of the group velocity (v g ) as well as the group velocity dispersion (GVD) along the propagation direction. Light will be dynamically localized and recur at certain Hermitian points, at which v g and GVD are recovered and averaged group velocity (v ḡ ) is zero.

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PT symmetry breaking in multilayers with resonant loss and gain locks light propagation direction

Cited by 67 publications

References 45 publications

Unambiguous scattering matrix for non-Hermitian systems

Unambiguous scattering matrix for non-Hermitian systems

A Better Photometric Index of Photo-Biological Effect on Visual Function of Human Eye: Illuminance or Luminance?

Hermiticity-tunable beam reshaping: localization, recurrence and group velocity oscillation

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