• Special Issue
  • Topological Photonics and Beyond
  • 6 Article (s)
Topological photonic crystal of large valley Chern numbers
Xiang Xi, Kang-Ping Ye, and Rui-Xin Wu
Photonics Research
  • Publication Date: Aug. 14, 2020
  • Vol. 8, Issue 9, 090000B1 (2020)
Creating locally interacting Hamiltonians in the synthetic frequency dimension for photons
Luqi Yuan, Avik Dutt, Mingpu Qin, Shanhui Fan, and Xianfeng Chen
The recent emerging field of synthetic dimension in photonics offers a variety of opportunities for manipulating different internal degrees of freedom of photons such as the spectrum of light. While nonlinear optical effects can be incorporated into these photonic systems with synthetic dimensions, these nonlinear effects typically result in long-range interactions along the frequency axis. Thus, it has been difficult to use the synthetic dimension concept to study a large class of Hamiltonians that involves local interactions. Here we show that a Hamiltonian that is locally interacting along the synthetic dimension can be achieved in a dynamically modulated ring resonator incorporating χ(3) nonlinearity, provided that the group velocity dispersion of the waveguide forming the ring is specifically designed. As a demonstration we numerically implement a Bose–Hubbard model and explore photon blockade effect in the synthetic frequency space. Our work opens new possibilities for studying fundamental many-body physics in the synthetic space in photonics, with potential applications in optical quantum communication and quantum computation.
Photonics Research
  • Publication Date: Aug. 27, 2020
  • Vol. 8, Issue 9, 090000B8 (2020)
Disorder-protected quantum state transmission through helical coupled-resonator waveguides
JungYun Han, Andrey A. Sukhorukov, and Daniel Leykam
We predict the preservation of temporal indistinguishability of photons propagating through helical coupled-resonator optical waveguides (H-CROWs). H-CROWs exhibit a pseudospin-momentum locked dispersion, which we show suppresses on-site disorder-induced backscattering and group velocity fluctuations. We simulate numerically the propagation of two-photon wave packets, demonstrating that they exhibit almost perfect Hong–Ou–Mandel dip visibility and then can preserve their quantum coherence even in the presence of moderate disorder, in contrast with regular CROWs, which are highly sensitive to disorder. As indistinguishability is the most fundamental resource of quantum information processing, H-CROWs may find applications for the implementation of robust optical links and delay lines in the emerging quantum photonic communication and computational platforms.
Photonics Research
  • Publication Date: Sep. 28, 2020
  • Vol. 8, Issue 10, 10000B15 (2020)
Manipulating light radiation from a topological perspective
Xuefan Yin, and Chao Peng
Manipulating radiation is important for a variety of optoelectronic applications, such as on-chip lasers, energy-efficient grating couplers, and antennas for light detection and ranging. Although designing and optimizing those optoelectronic devices are usually believed to be an engineering-oriented task, recent research reveals that the principles underlying radiation manipulation are closely connected to the concept of topology—the study of properties that are invariant under continuous deformations. In this review, we summarize a series of advances of the physics, phenomena, and applications related to radiation manipulation, in which topological concepts were adopted. Radiation could carry energy escaping from the system, breaking the energy conservation. The non-Hermiticity of such systems brings quite different physical consequences when comparing with the Hermitian counterparts and, hence, also results in the emergence of many interesting and extraordinary phenomena. In particular, it is found that the perfect trapping of light can still be realized in such non-Hermitian systems because of the photonic realization of bound states in the continuum. The fundamental nature of bound states in the continuum has been identified to be topological: they are essentially topological defects of the polarization vector field in momentum space, depicted by a kind of topological invariant named topological charges. Therefore, manipulation of radiation channels can be realized by controlling the topological charge evolution in momentum space. It is also demonstrated that the photonic states accompanied with different topological charges generate vortex beams with unique far-field radiation patterns, and ultra-fast switching of such vortex beams is demonstrated according to this principle. The progresses of topological photonics upon light radiation show that the topology is not just mathematical convenience for depicting photonic systems, but has brought realistic consequences in manipulating light and will boost the applications of photonics and optoelectronics in many aspects.
Photonics Research
  • Publication Date: Oct. 21, 2020
  • Vol. 8, Issue 11, 11000B25 (2020)
Topologically protected long-range coherent energy transfer
Yujing Wang, Jun Ren, Weixuan Zhang, Lu He, and Xiangdong Zhang
The realization of robust coherent energy transfer with a long range from a donor to an acceptor has many important applications in the field of quantum optics. However, it is hard to be realized using conventional schemes. Here, we demonstrate theoretically that robust energy transfer can be achieved using a photonic crystal platform, which includes the topologically protected edge state and zero-dimensional topological corner cavities. When the donor and the acceptor are put into a pair of separated topological cavities, the energy transfer between them can be fulfilled with the assistance of the topologically protected interface state. Such an energy transfer is robust against various kinds of defects, and can also occur over very long distances, which is very beneficial for biological detections, sensors, quantum information science, and so on.
Photonics Research
  • Publication Date: Oct. 30, 2020
  • Vol. 8, Issue 11, 11000B39 (2020)
Weak-value amplification for the optical signature of topological phase transitions
Weijie Wu, Shizhen Chen, Wenhao Xu, Zhenxing Liu, Runnan Lou, Lihua Shen, Hailu Luo, Shuangchun Wen, and Xiaobo Yin
We show that weak measurements can be used to measure the tiny signature of topological phase transitions. The signature is an in-plane photonic spin Hall effect, which can be described as a consequence of a Berry phase. It is also parallel to the propagation direction of a light beam. The imaginary part of the weak value can be used to analyze ultrasmall longitudinal phase shifts in different topological phases. These optical signatures are related to the Chern number and bandgaps; we also use a preselection and postselection technique on the spin state to enhance the original signature. The weak amplification technique offers a potential way to determine the spin and valley properties of charge carriers, Chern numbers, and topological phases by direct optical measurement.
Photonics Research
  • Publication Date: Nov. 05, 2020
  • Vol. 8, Issue 12, 12000B47 (2020)

Guest Editors:

Andrea Alu,
City University of New York, USA (Lead Editor)
Jingyun Fan,
Southern University of Science and Technology, China
Laura Pilozzi,
National Research Council, Italy
Haitan Xu,
Peking University, China


On the Cover for this virtual special issue

Topological photonics opens a new avenue to understand varieties of exotic and novel photonic phenomena, and it is expected to boost a series of key applications of photonics and optoelectronic in many aspects. See Xuefan Yin et al., page 11000B25.