“…1 . A substantial degenerate (or near-degenerate) FWM response is a prerequisite for applications of media in active optical systems ranging from modulators 2 , 3 to quantum repeaters 4 – 6 . Fig.…”
Third-order non-linearities are important because they allow control over light pulses in ubiquitous high-quality centro-symmetric materials like silicon and silica. Degenerate four-wave mixing provides a direct measure of the third-order non-linear sheet susceptibility χ(3)L (where L represents the material thickness) as well as technological possibilities such as optically gated detection and emission of photons. Using picosecond pulses from a free electron laser, we show that silicon doped with P or Bi has a value of χ(3)L in the THz domain that is higher than that reported for any other material in any wavelength band. The immediate implication of our results is the efficient generation of intense coherent THz light via upconversion (also a χ(3) process), and they open the door to exploitation of non-degenerate mixing and optical nonlinearities beyond the perturbative regime.
“…1 . A substantial degenerate (or near-degenerate) FWM response is a prerequisite for applications of media in active optical systems ranging from modulators 2 , 3 to quantum repeaters 4 – 6 . Fig.…”
Third-order non-linearities are important because they allow control over light pulses in ubiquitous high-quality centro-symmetric materials like silicon and silica. Degenerate four-wave mixing provides a direct measure of the third-order non-linear sheet susceptibility χ(3)L (where L represents the material thickness) as well as technological possibilities such as optically gated detection and emission of photons. Using picosecond pulses from a free electron laser, we show that silicon doped with P or Bi has a value of χ(3)L in the THz domain that is higher than that reported for any other material in any wavelength band. The immediate implication of our results is the efficient generation of intense coherent THz light via upconversion (also a χ(3) process), and they open the door to exploitation of non-degenerate mixing and optical nonlinearities beyond the perturbative regime.
“…However, the design at λ 0 = 1.56 µm still satisfies the bounds for a single nonlinear resonator, as indicated in Figure 1b. We also calculated the transmission in the dB scale, finding that T 12 = −50 dB at the peak transmission for T 21 when λ = 1.565 µm, demonstrating a large contrast in transmission, a sort of pseudo-isolation of 50 dB for this device at an incident power P inc = 18 GW/cm 2 . We stress that we should not consider this quantity as a conventional isolation metric, because it is based on the assumption that the two ports are excited independently, and the device cannot fully isolate in the general case of continuous wave excitation from opposite ports.…”
Section: Low Quality Factor Resonatorsmentioning
confidence: 92%
“…Optical nonreciprocity allows asymmetric light transmission from the opposite sides of a two-port device [1,2]. A common approach to break reciprocity is to utilize a magnetic bias [3,4], or in general a bias with odd symmetry under time-reversal, such that the propagating signals from opposite sides see entirely different devices.…”
Optical nonlinearities can enable unusual light–matter interactions, with functionalities that would be otherwise inaccessible relying only on linear phenomena. Recently, several studies have harnessed the role of optical nonlinearities to implement nonreciprocal optical devices that do not require an external bias breaking time-reversal symmetry. In this work, we explore the design of a metasurface embedding Kerr nonlinearities to break reciprocity for free-space propagation, requiring limited power levels. After deriving the general design principles, we demonstrate an all-dielectric flat metasurface made of coupled nonlinear Fano silicon resonant layers realizing large asymmetry in optical transmission at telecommunication frequencies. We show that the metrics of our design can go beyond the fundamental limitations on nonreciprocity for nonlinear optical devices based on a single resonance, as dictated by time-reversal symmetry considerations. Our work may shed light on the design of flat subwavelength free-space nonreciprocal metasurface switches for pulsed operation which are easy to fabricate, fully passive, and require low operation power. Our simulated devices demonstrate a transmission ratio >50 dB for oppositely propagating waves, an operational bandwidth exceeding 600 GHz, and an insertion loss of <0.04 dB.
“…Needless to say, the AI-empowered advancements have accelerated dramatically in a broad spectrum of nanophotonics and related fields, from design of novel metasurfaces to emulation of biological neural networks, and from materials discovery, optical characterizations to photonics technologies mediated by light-matter interaction [137][138][139][140][141][142]. It is truly amazing to see how the inverse design technique for arbitrary nanophotonic structures [143] has led to truly exciting applications such as chip-based LiDAR [144] and on-chip laser-driven particle accelerators [145] (Fig. 3b).…”
Section: Ai-empowered Nanophotonics and Photonic Machine-learningmentioning
Let there be light–to change the world we want to be! Over the past several decades, and ever since the birth of the first laser, mankind has witnessed the development of the science of light, as light-based technologies have revolutionarily changed our lives. Needless to say, photonics has now penetrated into many aspects of science and technology, turning into an important and dynamically changing field of increasing interdisciplinary interest. In this inaugural issue of eLight, we highlight a few emerging trends in photonics that we think are likely to have major impact at least in the upcoming decade, spanning from integrated quantum photonics and quantum computing, through topological/non-Hermitian photonics and topological insulator lasers, to AI-empowered nanophotonics and photonic machine learning. This Perspective is by no means an attempt to summarize all the latest advances in photonics, yet we wish our subjective vision could fuel inspiration and foster excitement in scientific research especially for young researchers who love the science of light.
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