Planar photonic crystal

We present results of guiding light in a single-line-defect planar photonic crystal (PPC) waveguide with 90° and 60° bends. The wave guiding is obtained by total internal reflection perpendicular to the plane of propagation and by the photonic band gap for the 2D photonic crystal in the plane. The results for photonic waveguiding are shown and demonstrated at 1.5 µm wavelength

Experimental and theoretical confirmation of Bloch-mode light propagation in planar photonic crystal waveguides

The dispersion diagram of the leaky modes in the planar photonic crystal waveguide is experimentally obtained for the wavelengths from 1440 to 1590 nm. A small stop band, around wavelength 1500 nm, is detected. The experimentally obtained results are in very good agreement with our three-dimensional finite difference time domain calculations. Propagation losses of the leaky modes are estimated and we have found that they decrease as we approach the ministop band

Waveguiding at 1550 nm using photonic crystal structures in silicon on insulator wafers

Design, fabrication and light guiding in planar photonic crystal structures including sharp corners with a bending radius less than 1 micron are demonstrated at 1550 nm wavelength in silicon waveguides on silicon dioxide substrates. Photon confinement in the sample plane was achieved by a photonic crystal structure while confinement in the vertical direction was achieved by index of refraction contrast

Experimental characterization of dispersion properties of leaky modes in planar photonic crystal waveguide

We have experimentally observed the coupling of a Bloch wave in a single-line-defect planar photonic crystal and have mapped the dispersion diagram of the leaky mode component of this wave. The results are in excellent agreement with our three-dimensional finite difference time domain calculations

Guiding and reflecting light by boundary material

We study effects of finite height and surrounding material on photonic crystal slabs of one- and two-dimensional photonic crystals with a pseudo-spectral method and finite difference time domain simulation methods. The band gap is shown to be strongly modified by the boundary material. As an application we suggest reflection and guiding of light by patterning the material on top/below the slab.Comment: 12 pages, 7 figure

Experimental characterization of dispersion properties of the leaky modes in planar photonic crystal waveguide

We have experimentally obtained the dispersion diagram of the leaky modes in a planar photonic crystal waveguide for wavelengths from 1440 nm to 1590 nm. A small stop band around λ=1500 nm is also detected. The experimental results are in very good agreement with our 3D FDTD calculations

PEN: a low energy test of lepton universality

Allowed charged $\pi$ meson decays are characterized by simple dynamics, few available decay channels, mainly into leptons, and extremely well controlled radiative and loop corrections. In that sense, pion decays represent a veritable triumph of the standard model (SM) of elementary particles and interactions. This relative theoretical simplicity makes charged pion decays a sensitive means for testing the underlying symmetries and the universality of weak fermion couplings, as well as for studying pion structure and chiral dynamics. Even after considerable recent improvements, experimental precision is lagging far behind that of the theoretical description for pion decays. We review the current state of experimental study of the pion electronic decay $\pi^+ \to e^+\nu_e(\gamma)$, or $\pi_{e2(\gamma)}$, where the $(\gamma)$ indicates inclusion and explicit treatment of radiative decay events. We briefly review the limits on non-SM processes arising from the present level of experimental precision in $\pi_{e2(\gamma)}$ decays. Focusing on the PEN experiment at the Paul Scherrer Institute (PSI), Switzerland, we examine the prospects for further improvement in the near term.Comment: 11 pages, 5 figures; paper presented at the XIII International Conference on Heavy Quarks and Leptons, 22-27 May 2016, Blacksburg, Virginia, US