The He-II (λ=30.4 nm) emission line is one of the spectral channels chosen to study solar corona. This Letter reports on investigations of novel beryllium (Be)/magnesium multilayer coatings which, when incorporated beneath a protective bilayer of aluminium and Be, ensure particularly high-reflection coefficients of up to 56%, a spectral width of Δλ=1.6 nm (λ/Δλ≈20), and high temporal stability.
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http://dx.doi.org/10.1364/OL.44.000263 | DOI Listing |
We present a novel, to the best of our knowledge, magneto-optical (MO) metasurface composed of a bismuth iron garnet (BIG) nanocube array, designed to achieve near-perfect absorption through quasi-bound states in the continuum (QBICs). This metasurface supports a stable QBIC mode induced by MO-induced permittivity terms that break the symmetry of the permittivity tensors, corresponding to a longitudinal electric dipole (ED) mode. By integrating graphene to introduce material loss, the absorption reaches 99.
View Article and Find Full Text PDFIn this paper, we demonstrate the selection of radiation from the stimulated Raman scattered radiation, while using a spectral filter, based on a high-reflection fiber Bragg grating and an optical circulator. As a result, a stable pulsed signal was obtained at a wavelength of 1125 nm with a repetition rate of 1 MHz. The pulse duration and energy varied from 120 to 173 ps and 9 to 15 nJ, respectively, depending on the operating regimes of the master oscillator and amplifier.
View Article and Find Full Text PDFWe demonstrate a distributed Bragg reflector fiber laser that is capable of long-term operation at ultra-high temperatures. To form the laser cavity, a piece of Er-doped fiber is fusion spliced to a pair of type II-IR gratings, which are written using a femtosecond laser with a phase mask. Saturated gratings with different reflectivities are fabricated by varying the position of the grating region relative to the fiber core center.
View Article and Find Full Text PDFWe demonstrate a high-temperature resistant distributed Bragg reflector (DBR) fiber laser that is highly compact with an entire cavity length of 12 mm. A partial-reflection tilted fiber Bragg grating (PR-TFBG) is used as the laser output coupler whose reflectivity can be adjusted by changing the TFBG tilt angle. The laser cavity consists of two strong gratings including the PR-TFBG and a high-reflection fiber Bragg grating (HR-FBG), which is directly fabricated in an Er-doped fiber using a femtosecond laser and a phase mask.
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