Subwavelength structured silicon waveguides and photonic devices

Abstract

<jats:title>Abstract</jats:title><jats:p>Subwavelength structures such as subwavelength gratings (SWGs) and subwavelength metamaterials are capable of tailoring the optical properties of materials and controlling the flow of light at the nanoscale. The effective indices of the subwavelength structured strip and slab waveguides can be changed in a wide range by choosing an appropriate duty cycle or a filling factor of silicon, which provides an effective method to manipulate the optical field and achieve effective index matching for functional devices. Recent advances in nanofabrication techniques have made it possible to implement subwavelength structures in silicon strip and slab waveguides. Here we review various approaches used to design subwavelength structures and achieve exotic optical responses and discuss how these structures can be used to realize high-performance silicon photonic devices. Both one-dimensional SWG devices and two-dimensional subwavelength metamaterial devices are covered in this review, including subwavelength structure–based polarization handling devices, mode manipulation devices, and building blocks for integrated optical interconnects. Perspectives on subwavelength structured silicon photonic devices are also discussed.</jats:p>

Subwavelength Grating Waveguide Structures Proposed on the Low-Cost Silica–Titania Platform for Optical Filtering and Refractive Index Sensing Applications

“…SWG waveguide with a certain grating period or duty cycle (hereafter represented as DC ) may be well-organized for each given wavelength band to be transmitted. The SWG waveguides are appealing because they allow the modification of the guided mode’s effective index and dispersion properties [ 16 ]. SWG waveguides are composed of periodic silicon segments that are smaller than the propagation wavelength, removing diffraction effects and acting like a typical waveguide made up of complementary birefringent material [ 17 ].…”

Silicon Multimode Waveguide Crossing Based on Anisotropic Subwavelength Gratings

“…Metamaterials have attracted a lot of attention because it provides a flexible approach to control the flow of light [26,27] including one-dimensional (1D) and two-dimensional (2D) subwavelength structures. In particular, subwavelength gratings (SWGs) have been widely used in silicon photonics for some special on-chip mode and polarization manipulation.…”

Design and Demonstration of Compact and Broadband Wavelength Demultiplexer Based on Subwavelength Grating (SWG)

“…SWGs are periodic structures that composed by interlaced segments of a high-refractive-index core material (e.g., Si) and a lowrefractive-index cladding material (e.g., air or SiO 2 ), where the reflection and diffraction effects are suppressed by using a grating pitch that much smaller than the operating wavelength [24]- [26]. As a result, the SWG is denoted as a homogeneous medium with an equivalent refractive index, which presents the potential of providing a new degree of freedom for device design by manipulating structural parameters [27]- [28]. Thus, it is a promising candidate for wavelength demultiplexer.…”