skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Roadmap on topological photonics
Abstract Topological photonics seeks to control the behaviour of the light through the design of protected topological modes in photonic structures. While this approach originated from studying the behaviour of electrons in solid-state materials, it has since blossomed into a field that is at the very forefront of the search for new topological types of matter. This can have real implications for future technologies by harnessing the robustness of topological photonics for applications in photonics devices. This roadmap surveys some of the main emerging areas of research within topological photonics, with a special attention to questions in fundamental science, which photonics is in an ideal position to address. Each section provides an overview of the current and future challenges within a part of the field, highlighting the most exciting opportunities for future research and developments.  more » « less
Award ID(s):
1809915
PAR ID:
10347562
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; « less
Date Published:
Journal Name:
Journal of Physics: Photonics
Volume:
4
Issue:
3
ISSN:
2515-7647
Page Range / eLocation ID:
032501
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. A miniature on-chip laser is an essential component of photonic integrated circuits for a plethora of applications, including optical communication and quantum information processing. However, the contradicting requirements of small footprint, robustness, single-mode operation, and high output power have led to a multi-decade search for the optimal on-chip laser design. During this search, topological phases of matter—conceived initially in electronic materials in condensed matter physics—were successfully extended to photonics and applied to miniature laser designs. Benefiting from the topological protection, a topological edge mode laser can emit more efficiently and more robustly than one emitting from a trivial bulk mode. In addition, single-mode operation over a large range of excitation energies can be achieved by strategically manipulating topological modes in a laser cavity. In this Perspective, we discuss the recent progress of topological on-chip lasers and an outlook on future research directions. 
    more » « less
  2. Topological photonics allows for the deterministic creation of electromagnetic modes of any dimensionality lesser than that of the system. In the context of two-dimensional systems such as metasurfaces, topological photonics enables trapping of light in 0D cavities defined by boundaries of higher-order topological insulators and topological defects, as well as guiding of optical fields along 1D boundaries between topologically distinct domains. More importantly, it allows engineering interactions of topological modes with radiative continuum, which opens new opportunities to control light-matter interactions, scattering, generation, and emission of light. This review article aims at highlighting recent work in the field focusing on the control of radiation and generation of light in topological metasurfaces. 
    more » « less
  3. Abstract Hyperbolic metamaterial (HMM) is a unique type of anisotropic material that can exhibit metal and dielectric properties at the same time. This unique characteristic results in it having unbounded isofrequency surface contours, leading to exotic phenomena such as spontaneous emission enhancement and applications such as super-resolution imaging. However, at optical frequencies, HMM must be artificially engineered and always requires a metal constituent, whose intrinsic loss significantly limits the experimentally accessible wave vector values, thus negatively impacting the performance of these applications. The need to reduce loss in HMM stimulated the development of the second-generation HMM, termed active HMM, where gain materials are utilized to compensate for metal’s intrinsic loss. With the advent of topological photonics that allows robust light transportation immune to disorders and defects, research on HMM also entered the topological regime. Tremendous efforts have been dedicated to exploring the topological transition from elliptical to hyperbolic dispersion and topologically protected edge states in HMM, which also prompted the invention of lossless HMM formed by all-dielectric material. Furthermore, emerging twistronics can also provide a route to manipulate topological transitions in HMMs. In this review, we survey recent progress in topological effects in HMMs and provide prospects on possible future research directions. 
    more » « less
  4. Topological boundary modes in electronic and classical-wave systems exhibit fascinating properties. In photonics, topological nature of boundary modes can make them robust and endows them with an additional internal structure—pseudo-spins. Here, we introduce heterogeneous boundary modes, which are based on mixing two of the most widely used topological photonics platforms—the pseudo-spin–Hall-like and valley-Hall photonic topological insulators. We predict and confirm experimentally that transformation between the two, realized by altering the lattice geometry, enables a continuum of boundary states carrying both pseudo-spin and valley degrees of freedom (DoFs). When applied adiabatically, this leads to conversion between pseudo-spin and valley polarization. We show that such evolution gives rise to a geometrical phase associated with the synthetic gauge fields, which is confirmed via an Aharonov-Bohm type experiment on a silicon chip. Our results unveil a versatile approach to manipulating properties of topological photonic states and envision topological photonics as a powerful platform for devices based on synthetic DoFs. 
    more » « less
  5. Classical wave systems have constituted an excellent platform for emulating complex quantum phenomena, such as demonstrating topological phenomena in photonics and acoustics. Recently, a new class of topological states localized in more than one dimension of a D -dimensional system, referred to as higher-order topological (HOT) states, has been reported, offering an even more versatile platform to confine and control classical radiation and mechanical motion. Here, we design and experimentally study a 3D topological acoustic metamaterial supporting third-order (0D) topological corner states along with second-order (1D) edge states and first-order (2D) surface states within the same topological bandgap, thus establishing a full hierarchy of nontrivial bulk polarization–induced states in three dimensions. The assembled 3D topological metamaterial represents the acoustic analog of a pyrochlore lattice made of interconnected molecules, and is shown to exhibit topological bulk polarization, leading to the emergence of boundary states. 
    more » « less