RF Photonics: An Optical Microcombs' Perspective Jiayang Wu; Xingyuan Xu; Nguyen, Thach G. ...
IEEE journal of selected topics in quantum electronics,
2018-July-Aug., 2018-7-00, Letnik:
24, Številka:
4
Journal Article
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Over the past decade, optical frequency combs generated by high-Q microresonators, or optical microcombs, which feature compact device footprints, low power consumption, and high repetition rates in ...broad optical bandwidths, have led to a revolution in a wide range of fields including metrology, telecommunications, radio frequency (RF) photonics, spectroscopy, sensing, and quantum optics. Among these, an application that has attracted great interest is the use of optical microcombs for RF photonics, where they offer enhanced functionalities as well as reduced size and power consumption over other approaches. This paper reviews the recent advances in this emerging field. We provide an overview of the main achievements that have been obtained to date, and highlight the strong potential of optical microcombs for RF photonics applications. We also discuss some of the open challenges and limitations that need to be addressed for practical applications.
The concept of optical bound states in the continuum (BICs) currently drives the field of dielectric resonant nanophotonics, providing an important physical mechanism for engineering high-quality ...(high-Q) optical resonances in high-index dielectric nanoparticles and structured dielectric metasurfaces. For structured metallic metasurfaces, realization of BICs remains a challenge associated with strong dissipative losses of plasmonic materials. Here, we suggest and realize experimentally anisotropic plasmonic metasurfaces supporting high-Q resonances governed by quasi-BIC collective resonant modes. Our metasurfaces are composed of arrays of vertically oriented double-pillar meta-molecules covered by a thin layer of gold. We engineer quasi-BIC modes and observe experimentally sharp resonances in mid-IR reflectance spectra. Our work suggests a direct route to boost the resonant field enhancement in plasmonic metasurfaces via combining a small effective mode volume of plasmonic systems with engineered high-Q resonances provided by the BIC physics, with multiple applications to enhance light-matter interaction for nano-optics and quantum photonics.
Convolutional neural networks, inspired by biological visual cortex systems, are a powerful category of artificial neural networks that can extract the hierarchical features of raw data to provide ...greatly reduced parametric complexity and to enhance the accuracy of prediction. They are of great interest for machine learning tasks such as computer vision, speech recognition, playing board games and medical diagnosis
. Optical neural networks offer the promise of dramatically accelerating computing speed using the broad optical bandwidths available. Here we demonstrate a universal optical vector convolutional accelerator operating at more than ten TOPS (trillions (10
) of operations per second, or tera-ops per second), generating convolutions of images with 250,000 pixels-sufficiently large for facial image recognition. We use the same hardware to sequentially form an optical convolutional neural network with ten output neurons, achieving successful recognition of handwritten digit images at 88 per cent accuracy. Our results are based on simultaneously interleaving temporal, wavelength and spatial dimensions enabled by an integrated microcomb source. This approach is scalable and trainable to much more complex networks for demanding applications such as autonomous vehicles and real-time video recognition.
We report a broadband RF channelizer based on an integrated optical frequency Kerr micro-comb source, with an RF channelizing bandwidth of 90 GHz, a high RF spectral slice resolution of 1.04 GHz, and ...experimentally verify the RF performance up to 19 GHz. This approach of realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave signal detection.
With superior optical properties, high flexibility in engineering its material properties, and strong capability for large‐scale on‐chip integration, graphene oxide (GO) is an attractive solution for ...on‐chip integration of 2D materials to implement functional integrated photonic devices capable of new features. Over the past decade, integrated GO photonics, representing an innovative merging of integrated photonic devices and thin GO films, has experienced significant development, leading to a surge in many applications covering almost every field of optical sciences such as photovoltaics, optical imaging, sensing, nonlinear optics, and light emitting. This paper reviews the recent advances in this emerging field, providing an overview of the optical properties of GO as well as methods for the on‐chip integration of GO. The main achievements made in GO hybrid integrated photonic devices for diverse applications are summarized. The open challenges as well as the potential for future improvement are also discussed.
The advances in the field of integrated graphene oxide (GO) photonics are reviewed. First, an overview of GO's optical properties, as well as methods for its on‐chip integration, are provided. Next, the main achievements made in GO hybrid integrated photonic devices for diverse applications are summarized. Finally, the open challenges as well as the potential for future improvement are discussed.
Micro-combs - optical frequency combs generated by integrated micro-cavity resonators - offer the full potential of their bulk counterparts, but in an integrated footprint. They have enabled ...breakthroughs in many fields including spectroscopy, microwave photonics, frequency synthesis, optical ranging, quantum sources, metrology and ultrahigh capacity data transmission. Here, by using a powerful class of micro-comb called soliton crystals, we achieve ultra-high data transmission over 75 km of standard optical fibre using a single integrated chip source. We demonstrate a line rate of 44.2 Terabits s
using the telecommunications C-band at 1550 nm with a spectral efficiency of 10.4 bits s
Hz
. Soliton crystals exhibit robust and stable generation and operation as well as a high intrinsic efficiency that, together with an extremely low soliton micro-comb spacing of 48.9 GHz enable the use of a very high coherent data modulation format (64 QAM - quadrature amplitude modulated). This work demonstrates the capability of optical micro-combs to perform in demanding and practical optical communications networks.
We demonstrate advanced transversal radio frequency (RF) and microwave functions based on a Kerr optical comb source generated by an integrated micro-ring resonator. We achieve extremely high ...performance for an optical true time delay aimed at tunable phased array antenna applications, as well as reconfigurable microwave photonic filters. Our results agree well with theory. We show that our true time delay would yield a phased array antenna with features that include high angular resolution and a wide range of beam steering angles, while the microwave photonic filters feature high Q factors, wideband tunability, and highly reconfigurable filtering shapes. These results show that our approach is a competitive solution to implementing reconfigurable, high performance and potentially low cost RF and microwave signal processing functions for applications including radar and communication systems.
Integrated Kerr micro-combs are a powerful source of multiple wavelength channels for photonic radio frequency (RF) and microwave signal processing, particularly for transversal filter systems. They ...offer significant advantages featuring a compact device footprint, high versatility, large numbers of wavelengths, and wide Nyquist bands. We review progress on photonic RF and microwave high bandwidth temporal signal processing based on Kerr micro-combs with comb spacings from 49 GHz to 200 GHz. We focus on integral and fractional Hilbert transforms, differentiators as well as integrators. The future potential of optical micro-combs for RF photonic applications in terms of functionality and ability to realize integrated solutions is also discussed.
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