scholarly journals Non-linear coherent perfect absorption in the proximity of exceptional points

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Suwun Suwunnarat ◽  
Yaqian Tang ◽  
Mattis Reisner ◽  
Fabrice Mortessagne ◽  
Ulrich Kuhl ◽  
...  
Keyword(s):  
Broad Band ◽  
Exceptional Point ◽  
Frequency Range ◽  
Perfect Absorption ◽  
Band Frequency ◽  
Exceptional Points ◽  
Coherent Perfect Absorption ◽  
Non Linear ◽  
Nonlinear Resonator ◽  
High Absorption

AbstractCoherent perfect absorption is one of the possibilities to get high absorption but typically suffers from being a resonant phenomena, i.e., efficient absorption only in a local frequency range. Additionally, if applied in high power applications, the understanding of the interplay of non-linearities and coherent perfect absorption is crucial. Here we show experimentally and theoretically the formation of non-linear coherent perfect absorption in the proximity of exceptional point degeneracies of the zeros of the scattering function. Using a microwave platform, consisting of a lossy nonlinear resonator coupled to two interrogating antennas, we show that a coherent incident excitation can trigger a self-induced perfect absorption once its intensity exceeds a critical value. Note, that a (near) perfect absorption persists for a broad-band frequency range around the nonlinear coherent perfect absorption condition. Its origin is traced to a quartic behavior that the absorbance spectrum acquires in the proximity of the exceptional points of the nonlinear scattering operator.

scholarly journals Frequency multiplication by collective nano-scale spin wave dynamics

2021 ◽  
Author(s):  
Georg Woltersdorf ◽  
Rouven Dreyer ◽  
Niklas Liebing ◽  
Chris Körner ◽  
Martin Wagener
Keyword(s):  
Broad Band ◽  
Ferromagnetic Layer ◽  
Low Frequency ◽  
Ferromagnetic Material ◽  
Frequency Multiplier ◽  
Frequency Multiplication ◽  
Band Frequency ◽  
Promising Alternative ◽  
Dynamic Phase ◽  
Non Linear

Abstract Frequency multiplication is a process where harmonic multiples of the input frequency are generated. It is usually achieved in non-linear electronic circuits or transmission lines. Such elements enable the up-conversion of electronic signals to GHz frequencies and are essential for frequency synthesizers and communication devices. Circuits based on the propagation and interaction of spin waves are a promising alternative to conventional electronics. Unfortunately, these systems usually require direct driving in the GHz range as magnonic frequency up-conversion is restricted to a few harmonics only. Here we show that the ferromagnetic material itself can act as a six octave spanning frequency multiplier. By studying low frequency magnetic excitations in a continuous ferromagnetic layer we show that the non-linearity of magnetization dynamics combined with disorder in the ferromagnet leads to the emergence of a dynamic phase generating high harmonics. The demonstrated broad band frequency multiplication opens exciting perspectives for magnonic and spintronic applications since the frequency is up-converted from MHz into GHz frequencies within the magnetic medium itself. Due to the ease at which magnetic media can be structured and modified spatially (and reversibly) we anticipate that a tailored non-linear dynamic phase can be engineered e.g. to stabilize magnetic solitons.

scholarly journals Exceptional Points in Non-Hermitian Photonic Crystals Incorporated With a Defect

2020 ◽  
Vol 10 (3) ◽  
pp. 823 ◽  
Author(s):  
Fangmei Liu ◽  
Dong Zhao ◽  
Hui Cao ◽  
Bin Xu ◽  
Wuxiong Xu ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Photonic Crystals ◽  
Perfect Absorption ◽  
Complex Phase ◽  
One Dimensional ◽  
Exceptional Points ◽  
Coherent Perfect Absorption ◽  
Highly Sensitive ◽  
Gain Loss ◽  
Highly Sensitive Sensors

We explored exceptional points (EPs) in one dimensional non-Hermitian photonic crystals incorporated with a defect. The defect was asymmetric with respect to the center. Two EPs could be derived by modulating the normalized frequency and the gain-loss coefficient of defect. The reflection coefficient complex phase changed dramatically around EPs, and the change in complex phase was π at EPs. The electric field of EPs was mainly restricted to the defect, which can induce a giant Goos–Hänchen (GH) shift. Moreover, we found a coherent perfect absorption-laser point (CPA-LP) in the structure. A giant GH shift also existed around the CPA-LP. The study may have found applications in highly sensitive sensors.

scholarly journals Parity-time symmetry and coherent perfect absorption in a cooperative atom response

Nanophotonics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 1357-1366
Author(s):  
Kyle E. Ballantine ◽  
Janne Ruostekoski
Keyword(s):  
Collective Excitation ◽  
Single Layer ◽  
Many Body ◽  
Dark Mode ◽  
Perfect Absorption ◽  
Exceptional Points ◽  
Nonexponential Decay ◽  
Time Symmetry ◽  
Coherent Perfect Absorption ◽  
Many Body Interactions

Abstract Parity-Time ( P T $\mathcal{P}\mathcal{T}$ ) symmetry has become an important concept in the design of synthetic optical materials, with exotic functionalities such as unidirectional transport and nonreciprocal reflection. At exceptional points, this symmetry is spontaneously broken, and solutions transition from those with conserved intensity to exponential growth or decay. Here, we analyze a quantum-photonic surface formed by a single layer of atoms in an array with light mediating strong cooperative many-body interactions. We show how delocalized collective excitation eigenmodes can exhibit an effective P T $\mathcal{P}\mathcal{T}$ symmetry and nonexponential decay. This effective symmetry is achieved in a passive system without gain by balancing the scattering of a bright mode with the loss from a subradiant dark mode. These modes coalesce at exceptional points, evidenced by the emergence of coherent perfect absorption where coherent incoming light is perfectly absorbed and scattered only incoherently. We also show how P T $\mathcal{P}\mathcal{T}$ symmetry can be generated in total reflection and by balancing scattering and loss between different polarizations of collective modes.

scholarly journals Coherent perfect absorption at an exceptional point

Science ◽  
2021 ◽  
Vol 373 (6560) ◽  
pp. 1261-1265
Author(s):  
Changqing Wang ◽  
William R. Sweeney ◽  
A. Douglas Stone ◽  
Lan Yang
Keyword(s):  
Exceptional Point ◽  
Perfect Absorption ◽  
Coherent Perfect Absorption

Organic Sub-Bandgap Schottky Barrier Photodetectors with Near-Infrared Coherent Perfect Absorption

ACS Photonics ◽  
2021 ◽  
Author(s):  
Yeonghoon Jin ◽  
Hyung Suk Kim ◽  
Junghoon Park ◽  
Seunghyup Yoo ◽  
Kyoungsik Yu
Keyword(s):  
Schottky Barrier ◽  
Near Infrared ◽  
Perfect Absorption ◽  
Coherent Perfect Absorption

scholarly journals Driving plasmonic nanoantennas at perfect impedance matching using generalized coherent perfect absorption

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Philipp Grimm ◽  
Gary Razinskas ◽  
Jer-Shing Huang ◽  
Bert Hecht
Keyword(s):  
Impedance Matching ◽  
Plasmonic Waveguide ◽  
Perfect Absorption ◽  
Single Nanowire ◽  
Coherent Perfect Absorption ◽  
Potential Applications ◽  
Plasmonic Nanoantennas ◽  
Radiative Losses ◽  
Additional Loss

Abstract Coherent perfect absorption (CPA) describes the absence of all outgoing modes from a lossy resonator, driven by lossless incoming modes. Here, we show that for nanoresonators that also exhibit radiative losses, e.g., plasmonic nanoantennas, a generalized version of CPA (gCPA) can be applied. In gCPA outgoing modes are suppressed only for a subset of (guided plasmonic) modes while other (radiative) modes are treated as additional loss channels - a situation typically referred to as perfect impedance matching. Here we make use of gCPA to show how to achieve perfect impedance matching between a single nanowire plasmonic waveguide and a plasmonic nanoantenna. Antennas with both radiant and subradiant characteristics are considered. We further demonstrate potential applications in background-free sensing.

Tunable coherent perfect absorption in three-dimensional Dirac semimetal films

2021 ◽  
Vol 19 (8) ◽  
pp. 081601
Author(s):  
Jipeng Wu ◽  
Jie Tang ◽  
Rongzhou Zeng ◽  
Xiaoyu Dai ◽  
Yuanjiang Xiang
Keyword(s):  
Three Dimensional ◽  
Perfect Absorption ◽  
Dirac Semimetal ◽  
Coherent Perfect Absorption
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