Optical polarization

About: Optical polarization is a research topic. Over the lifetime, 13992 publications have been published within this topic receiving 244284 citations.

The optical polarization of the Crab Pulsar

Abstract: Mesure des caracteristiques optiques du rayonnement directif emis par le pulsar du Crabe. Un nouveau modele est propose pour decrire la geometrie des regions emissives

Corrugated quantum well infrared photodetectors for normal incident light coupling

Abstract: In this letter, we report a quantum well infrared photodetector geometry for normal incidence light coupling. The new optical coupling scheme utilizes total internal reflection at the sidewalls of triangular wires to create favorable optical polarization for infrared absorption. These wires are created by chemically etching an array of V grooves through the detector active region along a specific crystallographic direction. Experimental results from the initial single color as well as two‐color detectors with linear wires and unthinned substrate show efficient light coupling comparable to the standard 45° edge coupling, without the undesirable wavelength dependence or spectral narrowing effect of a conventional grating structure. At the same time, the dark current density is substantially reduced due to the partial material removal. Further improvement is expected by creating a two‐dimensional coupling structure with substrate thinning.

Theory of Optical Gain of ${\hbox {Ge--}}{\hbox {Si}}_{x}{\hbox {Ge}}_{y}{\hbox {Sn}}_{1-x-y}$ Quantum-Well Lasers

Abstract: We develop a theoretical model for optical gain of a strained Ge--SixGeySn1-x-y quantum-well (QW) structure. By using a ternary SixGeySn1-x-y material system as the barriers, a tensile strained germanium QW with a direct band gap for the electron and hole confinements can be realized. We show our theoretical model for the strained band structure and the polarization dependent optical gain spectrum of the tensile strained germanium QW laser taking into account the carrier occupations in both the Gamma- and L-valleys of the conduction band. Reasonable material parameters are used to estimate the transition energy, optical gain spectrum, and effects of the carrier leakage in presence of the quantized subbands

Digital Equalisation of 40Gbit/s per Wavelength Transmission over 2480km of Standard Fibre without Optical Dispersion Compensation

Abstract: We demonstrate transmission and demodulation of 40Gbit/s per wavelength data, using 10Gbaud polarisation multiplexed QPSK. The digital coherent receiver includes carrier recovery and equalisation of all linear impairments, including chromatic dispersion and polarisation mode dispersion.

Visible Wavelength Planar Metalenses Based on Titanium Dioxide

Abstract: We present recent advances in metasurface-based photonics, which enables the realization of high performance planar lenses (metalenses) in the visible spectrum. They are enabled by a technique based on atomic layer deposition of titanium dioxide allowing for the fabrication of nanostructures with high fidelity. First, we demonstrate highly efficient metalenses with numerical aperture ${\rm{NA\,= \,0.8}}$ using the Pancharatnam-Berry phase approach. These metalenses can focus light into a diffraction-limited spot. They have efficiencies as high as 86% and provide high imaging resolution. Furthermore, by judicious design of the phase-shifting elements, we achieve a multispectral chiral metalens realized with a single metasurface layer. This chiral metalens can resolve both the chiral and spectral information of an object without the requirement of any additional optical components. Finally, we discuss the experimental realization of polarization-insensitive metalenses with NAs as high as 0.85. They are able to focus incident light to a spot as small as ∼0.64 λ with efficiencies up to 60%. Due to its straightforward and CMOS-compatible fabrication, this platform is promising for a wide range of applications ranging from camera modules, displays, laser-based imaging, microscopy, and spectroscopy to laser fabrication and lithography.