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The rapid development of silicon photonics inspired the emergence of on‐chip geometric optics. As one of the most crucial elements, waveguide‐lenses have attracted much attention. Nevertheless, waveguide‐lenses often suffer from large chromatism due to the strong waveguide dispersion, especially for the cases with multiple guided‐modes. In this paper, achromatic waveguide‐lenses available for multimode photonics are proposed and are further utilized for realizing multimode spot size converters (MSSCs) as an example. The present MSSC shows low excess losses < 0.4 dB and low inter‐mode crosstalks <−14 dB within an ultra‐broad bandwidth of 1450–1650 nm, which is realized for the first time by comprising a positive waveguide‐lens and a negative waveguide‐lens. In addition, the present MSSC is applied successfully for realizing high‐performance multimode waveguide corner‐bends. To the best of the knowledge, the proposed MSSC is the unique one with an ultra‐compact footprint and the largest bandwidth for low crosstalks as well as low losses, indicating that on‐chip geometric optics potentially provides a new perspective for on‐chip light manipulation desired in various applications. [ABSTRACT FROM AUTHOR]

Guided waves are the perfect carriers of electromagnetic signals in planar miniaturized devices due to their high localization and controlled propagation direction. However, it is still a challenge to control the polarization of propagating guided waves. In this work, the broadband polarization TE‐TM degeneracy of highly localized guided waves propagating along an all‐dielectric metasurface and a subwavelength chain of dielectric high‐index cylinders is discovered, both theoretically and experimentally. Using the discovered near‐field polarization degree of freedom, the polarization transformation for guided waves propagating along a subwavelength chain of dielectric cylinders at any frequency within the finite spectral range is demonstrated experimentally. Namely, the simplest planar near‐field polarization device – the quarter‐wave‐retardation (linear‐to‐circular) polarization transformer of guided waves is implemented. The results obtained discover the polarization degree of freedom for guided waves paving the way toward numerous applications in flat optics and planar photonics. [ABSTRACT FROM AUTHOR]

The article titled "Light Engineering and Silicon Diffractive Optics Assisted Nonparaxial Terahertz Imaging" explores the use of structured terahertz light in nonparaxial lensless imaging systems. The study focuses on the application of silicon diffractive optics to create Airy beams, which resemble a "THz sun," and illuminate Fresnel, Fibonacci, and Bessel shaped THz beams. The article, authored by Sergej Orlov, Rusnė Ivaškevičiūtė‐Povilauskienė, and their colleagues, provides a comprehensive analysis of the modulation transfer map dependencies on the distance between the imaged object and the optical element. [Extracted from the article]

Geometric phase is a unifying and central concept in physics, including optics. As a matter of fact, optics played a pivotal role from the inception of this new paradigm, as some of the first experimental demonstrations have been carried out in optics. A specific type of geometric phase was first introduced by Pancharatnam while investigating interference effects between different polarizations. This specific type of geometric phase, nowadays called the Pancharatnam–Berry phase, is related to the variation of light polarization, encompassing exotic properties when compared with the dynamic phase associated with the optical path. The most widespread manifestation of the Pancharatnam–Berry phase occurs in the presence of a twisted anisotropic material, yielding a point‐wise phase modulation proportional to the local rotation angle of the material. Here the basic mechanism behind the Pancharatnam–Berry phase is discussed. The various applications of this relatively original concept in photonics are then reviewed, presenting both the most important results and manufactured devices reported in literature. The interplay between geometric phase and diffraction occurring in bulk structures is discussed in detail. In the latter case it is shown how geometric phase can be harnessed to generate a new kind of optical waveguide without the necessity of any index gradient. [ABSTRACT FROM AUTHOR]

Guiding light in the low index region of a high refractive index contrast waveguide can be beneficial for many applications including sensing, nonlinear optics and electro-optics. Existing methods to achieve this goal suffer from fabrication complexity, large loss, or poor optical confinement. We propose a simple structure to achieve a significant enhancement of light confinement in the low index medium. We explain the guiding principle of this structure using geometrical optics, and suggest a number of applications where this guiding structure can provide significant performance benefits. The combination of simplicity, ease of fabrication, and good confinement makes this waveguide an attractive choice for a wide range of applications. To illustrate this, we consider the integration of a nonlinear polymer with a silicon photonic waveguide, and show that significantly better performance with an easier fabrication process can be achieved using this new scheme. [ABSTRACT FROM AUTHOR]

A major aim of researchers working in the field of optics and photonics is to mold the flow of light in optical structures and devices. In the regime of ballistic light propagation, transformation optics has given a certain boost, for which optical invisibility cloaking devices are striking examples. Our capability to mold the flow of light in the regime of diffuse light propagation in light-scattering media has fallen behind-while diffuse light from clouds, white wallpaper, computer monitors, and light-emitting diodes is literally all around us every day. In this review, we summarize progress in steering the flow of diffuse light in turbid media which was triggered by the mathematical analogy between electrostatics, magnetostatics, stationary heat conduction, and stationary light diffusion. We give an extensive tutorial introduction to the mathematics of the diffusion equation for light and its solutions, present an overview on the current experimental state-of-the-art of simple core-shell invisibility cloaking, and compare these experiments with diffusion theory as well as with more advanced modelling based on Monte Carlo simulations. The latter approach enables spanning the bridge from diffusive to ballistic light propagation. [ABSTRACT FROM AUTHOR]

One of the challenges of the modern photonics is to develop all-optical devices enabling increased speed and energy efficiency for transmitting and processing information on an optical chip. It is believed that the recently suggested Parity-Time (PT) symmetric photonic systems with alternating regions of gain and loss can bring novel functionalities. In such systems, losses are as important as gain and, depending on the structural parameters, gain compensates losses. Generally, PT systems demonstrate nontrivial non-conservative wave interactions and phase transitions, which can be employed for signal filtering and switching, opening new prospects for active control of light. In this review, we discuss a broad range of problems involving nonlinear PT-symmetric photonic systems with an intensity-dependent refractive index. Nonlinearity in such PT symmetric systems provides a basis for many effects such as the formation of localized modes, nonlinearly-induced PT-symmetry breaking, and all-optical switching. Nonlinear PT-symmetric systems can serve as powerful building blocks for the development of novel photonic devices targeting an active light control. [ABSTRACT FROM AUTHOR]

A table of contents for the 2016 issue of the journal "Laser & Photonics Reviews," is presented.

The table of contents for the January 2014 issue of "Laser & Photonics Reviews" is presented.

Single photons from a solid state source are deterministically routed into different output modes by a fully integrated active optical switch network. Using a state‐of‐the‐art single photon source made of a single quantum dot in a micropillar cavity and an innovative integrated optical demultiplexer, this scheme is capable of creating manifold single photon states. Such states are a crucial resource for photonic quantum information applications including linear optics quantum computation and quantum communications. (Picture: Mirko Lobino, Ph.D. et al., article number 1600297, in this issue) [ABSTRACT FROM AUTHOR]

Researchers in Australia report a novel approach to laser brightness scaling based on beam combination in a diamond Raman amplifier. Efficient power transfer to a Stokes input is demonstrated using a three pump beam arrangement. An analysis is also presented revealing that the concept may be applicable to continuous beam generation at kilowatt power levels and orders‐of‐magnitude higher when using isotopically purified diamond at reduced temperature. (Picture: Aaron McKay et al., article number 1600130 in this issue, Image credit: Ondrej Kitzler) [ABSTRACT FROM AUTHOR]

Information about the January 2014 issue of "Laser & Photonics Reviews" is presented. It lists the editorial advisors including Hans A. Bachor, Jeremy J. Baumberg and John T. Fourkas. It discusses the scope, main areas of interest, information for subscribers, customer services and disclaimer of the journal.

A chaotic microcavity coupled with a free-space laser beam. When the probe beam is on resonance with the high-Q regular mode, it leads to the cancellation of the chaos loss due to the destructive interference of two excitation pathways, which induces a transparency in the transmitted field. (Picture: Y.-F. Xiao et al., pp. L51-L54, in this issue) [ABSTRACT FROM AUTHOR]