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We report on the theoretical and experimental investigations of optical microcavities consisting in the plane-plane arrangement of a broadband high-reflectivity mirror and a suspended one-dimensional grating mirror possessing a high-quality factor Fano resonance. By varying the length of these cavities from the millimeter to the few-micron range, we observe at short lengths the reduction of the spectral linewidth predicted to occur for such a Fano cavity as compared to a conventional broadband mirror cavity with the same length and internal losses. Such narrow linewidth and small modevolume microcavities with high-mechanical quality ultrathin mirrors will be attractive for a wide range of applications within optomechanics and sensing.
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http://dx.doi.org/10.1364/OE.521329 | DOI Listing |
Sci Rep
August 2025
International Research Center of Spectroscopy and Quantum Chemistry, Siberian Federal University, Krasnoyarsk, Russia, 660041.
We consider resonances induced by symmetry protected bound states in the continuum in dielectric gratings with in-plane mirror symmetry. It is shown that the shape of the resonance in transmittance is controlled by two parameters in a generic formula which can be derived in the framework of the coupled mode theory. It is numerically demonstrated that the formula encompasses various line-shapes including asymmetric Fano, Lorentzian, and anti-Lorentzian resonances.
View Article and Find Full Text PDFNano Lett
September 2025
Institute of Physics (IA), RWTH Aachen University, D-52056 Aachen, Germany.
Metasurfaces have evolved as prime candidates for miniaturized optical components to tailor the light-matter interaction. Conventionally, the fabrication and design of such metasurfaces with complex antenna structures are well-developed and precise but need clean-room access and multiple fabrication steps. While metasurfaces based on polarization conversion are limited to low efficiencies, metasurfaces with antennas above a metallic mirror reach much higher efficiencies by keeping the initial polarization.
View Article and Find Full Text PDFOpt Express
February 2025
We report the development of a high-power, nanosecond gain-switched Ti:sapphire laser with a narrow spectral linewidth, achieved by a simple plano-plano cavity design and a volume Bragg grating (VBG) as the cavity end mirror. Pumped by a frequency-doubled Nd:YLF laser, the laser produced a maximum average power of 8.8 W at 775 nm, with a spectral linewidth of approximately 0.
View Article and Find Full Text PDFThis study introduces an optimization algorithm, Shapley-Guided Stochastic Optimization (SGSO), which incorporates Shapley values to steer the search towards optimal solutions. The algorithm was tested on some well-known global optimization benchmark functions, like the Easom and Ackley functions, to validate its efficiency before applying it to more complex real-world scenarios, like the inverse design of photonic structures, specifically a 3dB splitter, a grating coupler, and a multilayer broadband mirror. The SGSO algorithm demonstrated its capability to direct the search process to generate highly performing designs while maintaining computational efficiency.
View Article and Find Full Text PDFWe report a monolithic low-loss short-length gain-switched thulium-doped fiber laser (TDFL) beyond 2.1 µm. Phase-mask-assisted 800-nm femtosecond laser exposure method was used to fabricate the monolithic laser cavity on ∼10-cm long straightened silica Tm-doped fiber (TDF) after single-shot spatial alignment.
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