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An eight‐channel hybrid‐integrated light source with 100 GHz channel spacing fabricated by a passive alignment technology is demonstrated. Side mode suppression ratios of better than 40 dB were obtained via grating couplers under eight‐channel simultaneous operation at a continuous wave current of 600 mA and 25°C. The surface slotted laser array fabricated by standard lithography butt‐joint with silicon photonic devices was demonstrated for the first time, to the best of the authors' knowledge. [ABSTRACT FROM AUTHOR]

Abstract: Resonant waveguide gratings (RWGs), also known as guided mode resonant (GMR) gratings or waveguide‐mode resonant gratings, are dielectric structures where these resonant diffractive elements benefit from lateral leaky guided modes from UV to microwave frequencies in many different configurations. A broad range of optical effects are obtained using RWGs such as waveguide coupling, filtering, focusing, field enhancement and nonlinear effects, magneto‐optical Kerr effect, or electromagnetically induced transparency. Thanks to their high degree of optical tunability (wavelength, phase, polarization, intensity) and the variety of fabrication processes and materials available, RWGs have been implemented in a broad scope of applications in research and industry: refractive index and fluorescence biosensors, solar cells and photodetectors, signal processing, polarizers and wave plates, spectrometers, active tunable filters, mirrors for lasers and optical security features. The aim of this review is to discuss the latest developments in the field including numerical modeling, manufacturing, the physics, and applications of RWGs. Scientists and engineers interested in using RWGs for their application will also find links to the standard tools and references in modeling and fabrication according to their needs. [ABSTRACT FROM AUTHOR]

Periodic structures with a sub-wavelength pitch have been known since Hertz conducted his first experiments on the polarization of electromagnetic waves. While the use of these structures in waveguide optics was proposed in the 1990s, it has been with the more recent developments of silicon photonics and high-precision lithography techniques that sub-wavelength structures have found widespread application in the field of photonics. This review first provides an introduction to the physics of sub-wavelength structures. An overview of the applications of sub-wavelength structures is then given including: anti-reflective coatings, polarization rotators, high-efficiency fiber-chip couplers, spectrometers, high-reflectivity mirrors, athermal waveguides, multimode interference couplers, and dispersion engineered, ultra-broadband waveguide couplers among others. Particular attention is paid to providing insight into the design strategies for these devices. The concluding remarks provide an outlook on the future development of sub-wavelength structures and their impact in photonics. [ABSTRACT FROM AUTHOR]

A new plasmonic device architecture based on ultrasmooth metallic surfaces with buried plasmonic nanostructures is presented. Using template-stripping techniques, ultrathin gold films with less than 5 Å surface roughness are optically coupled to an arbitrary arrangement of buried metallic gratings, rings, and nanodots. As a prototypical example, linear plasmonic gratings buried under an ultrasmooth 20 nm thick gold surface for biosensing are presented. The optical illumination and collection are completely decoupled from the microfluidic delivery of liquid samples due to the backside, reflection-mode geometry. This allows for sensing with opaque or highly scattering liquids. With the buried nanostructure design, high sensitivity and decoupled backside (reflective) optical access are maintained, as with traditional prism-based surface plasmon resonance (SPR) sensors. In addition, the benefits offered by nanoplasmonic sensors such as spectral tunability and high-resolution, wide-field SPR imaging with normal-incidence epi-illumination that is simple to construct and align are gained as well. Beyond sensing, the buried plasmonic nanostructures with ultrasmooth metallic surfaces can benefit nanophotonic waveguides, surface-enhanced spectroscopy, nanolithography, and optical trapping. [ABSTRACT FROM AUTHOR]

Planar devices for light transmission between diamond integrated optical circuits and optical fibers or microscope objectives (called grating couplers) can be fabricated by capacitively coupled reactive ion etching (RIE) through contact hard masks micropatterned by e‐beam lithography. However, sidewalls of such etched structures cannot be vertical because their steepness is limited by etching conditions. This study is devoted to numerical simulations of wall steepness influence on diamond‐based grating coupler efficiency at 637 and 1550 nm wavelengths. A simple genetic algorithm to find the optimal device geometry is used herein. The maximum grating coupler efficiency remains almost constant at the wall steepness from 90° to 60° and decreases at lower values. In the specified range, changes in the wall steepness can be fully compensated by changing the width of grating coupler ridges (fill factor). Lowering the wall steepness gives rise to other parameters' tolerances. The study proves that fast and robust capacitively coupled RIE of diamond is a suitable method for creating diamond grating couplers. [ABSTRACT FROM AUTHOR]