Salisburygundersen9357

Aluminum gallium arsenide has highly desirable properties for integrated parametric optical interactions large material nonlinearities, maturely established nanoscopic structuring through epitaxial growth and lithography, and a large bandgap for broadband low-loss operation. However, its full potential for record-strength nonlinear interactions is only released when the semiconductor is embedded within a dielectric cladding to produce highly confining waveguides. From simulations of such, we present second- and third-order pair generation that could improve upon state-of-the-art quantum optical sources and make novel regimes of strong parametric photon-photon nonlinearities accessible.A class of self-similar beams, the Platonic Gaussian beams, is introduced by using the vertices of the Platonic solids in a Majorana representation. Different orientations of the solids correspond to beams with different profiles connected through astigmatic transformations. The rotational symmetries of the Platonic solids translate into invariance to specific optical transformations. While these beams can be considered as "the least ray-like" for their given total order, a ray-based description still offers insight into their distribution and their transformation properties.Reflection-mode ultraviolet photoacoustic microscopy (UV-PAM) is capable of imaging cell nuclei in thick tissue without complex preparation procedures, but it is challenging to distinguish adjacent nuclei due to the limited spatial resolution. Tissue expansion technology has recently been developed to exceed the diffraction-limited fluorescence microscopies, but it is accompanied by limitations including additional staining. Herein, photoacoustic expansion microscopy (PAExM) is presented, which is an advanced histologic imaging strategy combining advantages of fast label-free reflection-mode UV-PAM and the tissue expansion technology. Clustered cell nuclei in an enlarged volume of a mouse brain section can be visually resolved without staining, demonstrating a great potential of the system to be widely used for histologic applications throughout biomedical fields.A focused Gaussian beam represents a case of highly practical importance in many areas of optics and photonics. We derive analytical expressions for a focused Gaussian beam in the paraxial approximation, considering an arbitrary lens filling factor. We discuss the role of higher-order Bessel functions of the first kind in defining the electric field in the focal region.It has recently been shown that counter-intuitive Franson-like second-order interference can be observed with a pair of classically correlated pseudo thermal light beams and two separate unbalanced interferometers (UIs) the second-order interference visibility remains fixed at 1/3 even though the path length difference in each UI is increased significantly beyond the coherence length of the pseudo thermal light [Phys. Rev. Lett.119, 223603 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.223603]. However, as the pseudo thermal beam itself originated from a long-coherence laser (and by using a rotating ground disk), there exists the possibility of a classical theoretical model to account for second-order interference beyond the coherence time on the long coherence time of the original laser beam. In this work, we experimentally explore this counter-intuitive phenomenon with a true thermal photon source generated via quantum thermalization, i.e., obtaining a mixed state from a pure two-photon entangled state. This experiment not only demonstrates the unique second-order coherence properties of thermal light clearly but may also open up remote sensing applications based on such effects.UV supercontinuum laser sources based on resonant dispersive wave (RDW) generation in gas-filled hollow-core (HC) fibers offer an attractive architecture for numerous applications. However, the narrow UV spectral peak inherent to RDW generation limits the suitability for applications that require broad spectral coverage within the UV region such as spectroscopic scatterometry. In this Letter, we demonstrate how the UV spectrum can be shaped by modulating the peak power of the pump pulses driving the RDW generation, thereby creating a broadened and flattened UV spectrum. Using an argon-filled anti-resonant HC fiber, we generate a UV spectrum with a center wavelength of 323.6 nm with an FWHM of 51.7 nm, corresponding to a relative bandwidth of 16.1%.We demonstrate theoretically and experimentally a novel photonic spin Hall effect (PSHE), to the best of our knowledge, at an interface between air and uniaxial crystal, whose optical axis is within the interface plane. Owing to the anisotropy of the crystal, partial cross polarization conversion occurs. For a horizontally polarized paraxial Gaussian beam incidence, a linear polarization gradient forms along the in-plane wavevector in the reflected beam, allowing us to achieve spin separation in real space. The spin separation of the reflected beam can be tuned by rotating the optical axis of the crystal. A maximum spin-dependent displacement up to 0.45 times the incident beam waist is obtained at Brewster incidence. click here This novel anisotropy-induced PSHE deepens the understanding of spin-orbit interaction and provides a new way for control of spin photons.We experimentally demonstrate the direct strong coupling between the S0→S1 absorption transition of rhodamine 6G (R6G) dye molecules and the surface plasmon polaritons of a hyperbolic metamaterial (HMM) substrate. The surface plasmon mode was excited by a guided mode of the R6G-doped polymer thin film on the HMM. The coupling strengths of the interactions between the surface plasmon and two molecular exciton modes are greater than the average linewidths of the individual modes indicating a strong coupling regime. This is the first, to the best of our knowledge, experimental demonstration of the direct strong coupling between the resonance mode supported by the HMM and the dye molecules on the HMM surface, not embedded in the HMM structure. The study may provide the foundation for the development of novel planar photonic or electronic devices.