Morse Roche (burnbumper46)

The selective excitation of localized surface wave modes remains a challenge in the design of both leaky-wave and bound-wave devices. In this Letter, we show how the truncation of a metasurface can play an important role in breaking the spatial inversion symmetry in the excitation of surface waves supported by the structure. This is done by combining a large anisotropy in the dispersion relation and the presence of an edge that also serves as a coupling mechanism between the plane wave excitation and the induced surface waves. By resorting to the exact solution to the scattering problem based on a discrete Wiener-Hopf technique, we show that by inverting the component of the impinging wavevector parallel to the truncation, two distinct surface waves are excited.Narrow-band terahertz (THz) Cherenkov radiation can be excited as a relativistic electron bunch passes through the dielectric capillary with sub-millimeter radius. However, due to the diffraction effect, the radiation will enter free space with a large divergence angle, which makes it difficult to collect the radiation energy efficiently. Irpagratinib In this Letter, to deal with this challenge, we propose to add a new dielectric layer, which satisfies a special relationship with the electron velocity, between the metal coating and original dielectric layer in the capillary. According to numerical simulation and theoretical analysis results, the divergence angle of radiation is significantly suppressed, and the peak power density is also enhanced by over two orders. As a result, the transmission efficiency from the radiation source to the optical system can be increased to over 90%. We expect that this method will provide a new way to generate THz Cherenkov radiation.Upon excitation with extreme ultraviolet (EUV) radiation, optical windows CaF2 and sapphire emit strong photoluminescence (PL) in the ultraviolet region 200-400 nm. The spectral profiles of the windows observed in the PL spectra appear strongly dependent on their temperature. We suggest the use of PL spectra of CaF2 and sapphire excited with EUV light to indicate the temperature for EUV applications such as nano-photolithography technology in manufacturing semiconductor devices; potentially, the method is applicable to a wide range of radiation including the vacuum-ultraviolet (VUV) and EUV regions and in all fields.We present an all-passive efficient KGW Raman laser with an external-cavity configuration in the 2 µm spectral regime. The Raman laser was pumped by a passively Q-switched TmYAP laser emitting at 1935 nm. Due to the bi-axial properties of the KGW crystal, the laser exhibits stimulated Raman emission at two separate spectral lines 2272 nm and 2343 nm. The output energies achieved at these two lines are 340 µJ/pulse and 450 µJ/pulse, accordingly. The seed to Raman laser conversion efficiencies achieved of 19.2% and 23.5%, respectively, are comparable to actively Q-switched laser arrangements. To the best of our knowledge, this is the first time an efficient Raman laser in the 2 µm regime is demonstrated in a completely passive configuration.Fourier ptychographic microscopy (FPM) is a computational approach geared towards creating high-resolution and large field-of-view images without mechanical scanning. Acquiring color images of histology slides often requires sequential acquisitions with red, green, and blue illuminations. The color reconstructions often suffer from coherent artifacts that are not presented in regular incoherent microscopy images. As a result, it remains a challenge to employ FPM for digital pathology applications, where resolution and color accuracy are of critical importance. Here we report a deep learning approach for performing unsupervised image-to-image translation of FPM reconstructions. A cycle-consistent adversarial network with multiscale structure similarity loss is trained to perform virtual brightfield and fluorescence staining of the recovered FPM images. In th