Topological charge of finite-size photonic crystal modes

Wang, Zhixin; Liang, Yong; Beck, Matthias; Scalari, Giacomo; Faist, Jérôme

doi:10.1103/physrevb.102.045122

Cited by 15 publications

(15 citation statements)

References 40 publications

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“…2a shows the mode magnetic field profile H z at the Γ point of the fundamental TE-like band in a photonic crystal slab with 15 × 15 periods. Unlike the infinite-size cavity, the mode profile shows an envelope distribution with a convex shape accompanied by mode leakage into free space 25,27 . This finite-size effect results in the mode broadening Δk (white circle) in the k-space field distribution, FT(H z ) (Fig.…”

Section: Resultsmentioning

confidence: 99%

Ultralow-threshold laser using super-bound states in the continuum

et al. 2021

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Wavelength-scale lasers provide promising applications through low power consumption requiring for optical cavities with increased quality factors. Cavity radiative losses can be suppressed strongly in the regime of optical bound states in the continuum; however, a finite size of the resonator limits the performance of bound states in the continuum as cavity modes for active nanophotonic devices. Here, we employ the concept of a supercavity mode created by merging symmetry-protected and accidental bound states in the continuum in the momentum space, and realize an efficient laser based on a finite-size cavity with a small footprint. We trace the evolution of lasing properties before and after the merging point by varying the lattice spacing, and we reveal this laser demonstrates the significantly reduced threshold, substantially increased quality factor, and shrunken far-field images. Our results provide a route for nanolasers with reduced out-of-plane losses in finite-size active nanodevices and improved lasing characteristics.

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Section: Resultsmentioning

confidence: 99%

Ultralow-threshold laser using super-bound states in the continuum

et al. 2021

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“… 5 − 9 Polarization textures are also widely applied in beam engineering, lasing, and holography. 10 − 14 …”

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confidence: 99%

Polarization and Phase Textures in Lattice Plasmon Condensates

et al. 2021

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Polarization textures of light may reflect fundamental phenomena, such as topological defects, and can be utilized in engineering light beams. They have been observed, for instance, in photonic crystal lasers and semiconductor polariton condensates. Here we demonstrate domain wall polarization textures in a plasmonic lattice Bose–Einstein condensate. A key ingredient of the textures is found to be a condensate phase that varies spatially in a nontrivial manner. The phase of the Bose–Einstein condensate is reconstructed from the real- and Fourier-space images using a phase retrieval algorithm. We introduce a simple theoretical model that captures the results and can be used for design of the polarization patterns and demonstrate that the textures can be optically switched. The results open new prospects for fundamental studies of non-equilibrium condensation and sources of polarization-structured beams.

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“…Very recently, both symmetry protected as well as accidental BICs were reported to exhibit lasing action. 14,[20][21][22][23] For symmetry protected BICs, lasing for both TE and TM-like BICs with +1 and -1 topological charges have been observed at the Γ-point of a square lattice. In each of the above reports, either one or two out of four possible BICs exhibited lasing.…”

Section: Introductionmentioning

confidence: 99%

Topological charge engineering in lasing bound states in continuum

Mohamed,

Wang,

Rekola

et al. 2020

Preprint

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Recently, optical bound states in continuum in various passive photonic crystals have been identified and similar structures incorporated with optical gain have been reported to exhibit lasing. However, no explicit control over the type of lasing BIC has been reported. In this work, we utilize all four fundamental BICs related to the lowest energy Γ-point of a square photonic crystal lattice. We identify the associated topological charges from experimentally obtained dispersions, finite element method simulations, as well as from spherical decomposition method based on the microscopic polarization currents in the photonic crystal plane. By tailoring the periodicity and the hole diameter of the photonic crystal slab, we selectively bring each of the four BIC resonances to a wavelength regime, where fluorescent IR702 molecules overlaid with the photonic crystal provide sufficient gain for the onset of lasing. We experimentally analyze all four observed lasing BICs by imaging their far-field polarization vortices and their associated topological charges. The results correspond excellently with the transmission results as well as the simulation results in the absence of gain. Finally, we experimentally present a case where the lasing signal reveals the coexistence of two BICs with opposite topological charges, resulting in a unique polarization pattern. We believe our results enable tailoring the properties, such as polarization winding and topological charge of BICs, by a priori design and thus pave the way for a more general utilization of their appealing properties.

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Topological charge of finite-size photonic crystal modes

Cited by 15 publications

References 40 publications

Ultralow-threshold laser using super-bound states in the continuum

Ultralow-threshold laser using super-bound states in the continuum

Polarization and Phase Textures in Lattice Plasmon Condensates

Topological charge engineering in lasing bound states in continuum

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