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Parity-time-reciprocal scaling (PTX)-symmetry has been recently proposed to tailor the resonance linewidth and gain threshold of non-Hermitian systems with new exhilarating applications, such as coherent perfect absorber-laser (CPAL) and exceptional point (EP)-based devices. Here, we put forward a nearly-lossless, low-index metachannel formed byPTX-symmetric metasurfaces operating at the CPAL point, supporting the undamped weakly-guided fast wave (leaky mode) and thus achieving ultradirective leaky-wave radiation. Moreover, this structure allows for a reconfigurable and tunable radiation angle as well as beamwidth determined by the reciprocally scaled gain-loss parameter. We envision that the proposedPTX-symmetric metasurfaces will shed light on the design of antennas and emitters with ultrahigh directionality, as well as emerging applications enabled by extreme material properties, such as epsilon-near-zero (ENZ) and beyond.
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Superdirective leaky radiation from a PT-synthetic metachannel
Spectral singularities appearing in parity-time (PT)-symmetric non-Hermitian optical systems have aroused a growing interest due to their new exhilarating applications, such as bifurcation effects at exceptional points and the coexistence of coherent perfect absorber and laser (so-called CPAL point). We introduce here how the concept of CPAL action provoked inPT-symmetric metasurfaces can be translated into practical implementation of a low-loss zero/low-index open channel supporting a nearly undamped fast-wave propagation. Such aPT-synthetic metachannel shows the capability to produce a high-directivity leaky radiation, with a tunable beam angle that depends on the gain-loss parameter. The proposed structure may enable new kinds of super-directivity antennas, as well as many applications that demand extreme dielectric properties, such as epsilon-near-zero (ENZ).
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- Award ID(s):
- 1917678
- PAR ID:
- 10220648
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 29
- Issue:
- 8
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 12330
- Size(s):
- Article No. 12330
- Sponsoring Org:
- National Science Foundation
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