- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Low-loss and broadband non-volatile phase-change directional coupler switches
摘要： An optical equivalent of the field-programmable gate array (FPGA) is of great interest to large-scale photonic integrated circuits. Previous programmable photonic devices relying on the weak, volatile thermo-optic or electro-optic effect usually suffer from a large footprint and high energy consumption. Phase change materials (PCMs) offer a promising solution due to the large non-volatile change in the refractive index upon phase transition. However, the large optical loss in PCMs poses a serious problem. Here, by exploiting an asymmetric directional coupler design, we demonstrate non-volatile PCM-clad silicon photonic 1 × 2 and 2 × 2 switches with a low insertion loss of ~1 dB and a compact coupling length of ~30 μm while maintaining a small crosstalk less than ?10 dB over a bandwidth of 30 nm. The reported optical switches will function as the building blocks of the meshes in the optical FPGAs for applications such as optical interconnects, neuromorphic computing, quantum computing, and microwave photonics.
关键词： Silicon photonics,Non-volatile,Optical switches,Phase-change materials,Reconfigurable photonics,Integrated photonic devices
更新于2025-09-23 15:23:52
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Nanoplasmonics || Plasmonic Nanoantenna Array Design
摘要： Recently, wireless optical communication system is developing toward the chip level. Optical nanoantenna array in optical communication system is the key component for radiating and receiving light. In this chapter, we propose a sub-wavelength plasmonic nanoantenna with high gain operating at the standard optical communication wavelength of 1550 nm. The designed plasmonic antenna has a good matching with the silicon waveguide in a wide band, and light is fed from the bottom of the nanoantenna via the silicon waveguide. Furthermore, we design two kinds of antenna arrays with the proposed plasmonic nanoantenna, including one- and two-dimensional arrays (1 × 8 and 8 × 8). The radiation characteristics of the antenna arrays are investigated and both arrays have high gains and wide beam steering range without grating lobes.
关键词： localized surface plasmon,radiation characteristics,integrated photonic devices,plasmonic nanoantenna,integrated optical antenna arrays
更新于2025-09-23 15:21:01
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Demonstration of low loss <b> <i>β</i> </b> -Ga <sub/>2</sub> O <sub/>3</sub> optical waveguides in the UV–NIR spectra
摘要： In this paper, we report the fabrication of low loss beta-phase gallium oxide (b-Ga2O3) optical waveguides and the propagation loss analysis of the waveguides in the ultraviolet (UV) to near infrared (NIR) spectral region. The b-Ga2O3 thin films were grown on sapphire substrates using metal organic chemical vapor deposition and were fabricated into various waveguide structures using nanofabrication processes. A low propagation loss of 3.7 dB/cm was obtained on the b-Ga2O3 waveguide at the wavelength of 810 nm, which is comparable to the state of the art. Combined with theoretical simulations, various loss mechanisms from two-photon absorption, sidewall scattering, top surface scattering, and bulk scattering were discussed for b-Ga2O3 waveguides, and their contributions to the total optical loss were estimated. These results show that b-Ga2O3 is a promising optical material for the fabrication of various integrated photonic devices in the UV–NIR spectra region.
关键词： integrated photonic devices,b-Ga2O3,propagation loss,UV–NIR spectra,optical waveguides
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Adiabatic Transitions between Supersymmetric Structures as a Tool to Design Integrated Photonic Devices
摘要： Supersymmetry (SUSY), originally developed to unify the mathematical treatment of bosons and fermions, is a powerful mathematical tool with many applications in both non-relativistic quantum mechanics and Helmholtz optics [1]. The application of SUSY to optical systems has attracted a lot of attention, e.g. for mode filtering and multiplexing [2,3], exploiting the global phase-matching conditions among all the modes of two superpartner structures, except for the fundamental mode. So far, SUSY transformations have been proposed in a discrete way, i.e., evanescently coupling the superpartner structures. Here, instead, we introduce adiabatic transitions connecting superpartner profiles by smoothly modifying the transverse refractive index profile along the propagation direction, offering a new way to manipulate the modal content in systems of optical waveguides and to engineer efficient and robust photonic integrated devices [4]. The propagation of the transverse electric (TEm) component of the electric field along z-direction through a medium with arbitrary index of refraction n(x,z) can be described by the Helmholtz equation. At any fixed position, the problem is described by ?(cid:1857)(cid:3040)((cid:1876)) = (cid:2010)(cid:3040)(cid:2870) (cid:1857)(cid:3040)((cid:1876)), where (cid:1857)(cid:3040)((cid:1876)) is the transverse spatial distribution, and (cid:2010)(cid:3040) is the propagation constant of mode m. By factorizing the Hamiltonian using SUSY techniques, the superpartner index profiles can be derived [1]. To achieve a transition connecting two superpartner profiles (cid:1866)((cid:3044)(cid:2879)(cid:2869))((cid:1876)) and (cid:1866)((cid:3044))((cid:1876)), we introduce a continuous transformation function (cid:1859)(cid:3044)((cid:1878)) valued between 0 and 1: , where (cid:1849) ((cid:3044)(cid:2879)(cid:2869))((cid:1876)) = ?(cid:2034)(cid:3051)(cid:1864)(cid:1866)(cid:1857)(cid:2868)(cid:1856)(cid:1849) ((cid:3044)(cid:2879)(cid:2869))((cid:1876))(cid:1856)(cid:1876) is the superpotential and q identifies the number of discrete SUSY transformations applied (see Fig. 1(a)). In particular, we demonstrate that such transformations provide a systematic way to design efficient and robust tapered waveguides and mode filters by using single-waveguide structures (see Fig. 1(b)), and beam splitters (see Fig. 1(c)) and Mach-Zehnder Interferometers (MZI) by using two-waveguide structures. Numerically calculated fidelities above 0.999 and above 0.99 are achieved in a broad region of wavelengths for L > 1.8mm tapered waveguides and L>6mm symmetric beam splitters, respectively. Moreover, we design a single-waveguide mode filter with fidelities above 0.9 and a MZI with a visibility of 98.6%. Although we apply continuous SUSY transformations to single- and two-waveguide structures, more complex structures could be designed by increasing the number of waveguides, using waveguides with different widths, using optical fibers or combining continuous with discrete SUSY transformations. Such SUSY transformations could be incorporated in the design of novel quantum integrated photonic devices and even extended to other quantum platforms such as in atomtronics.
关键词： Supersymmetry,integrated photonic devices,adiabatic transitions,optical waveguides,mode filtering
更新于2025-09-12 10:27:22
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Inverse photonic design of functional elements that focus Bloch surface waves
摘要： Bloch surface waves (BSWs) are sustained at the interface of a suitably designed one-dimensional (1D) dielectric photonic crystal and an ambient material. The elements that control the propagation of BSWs are defined by a spatially structured device layer on top of the 1D photonic crystal that locally changes the effective index of the BSW. An example of such an element is a focusing device that squeezes an incident BSW into a tiny space. However, the ability to focus BSWs is limited since the index contrast achievable with the device layer is usually only on the order of Δn≈0.1 for practical reasons. Conventional elements, e.g., discs or triangles, which rely on a photonic nanojet to focus BSWs, operate insufficiently at such a low index contrast. To solve this problem, we utilize an inverse photonic design strategy to attain functional elements that focus BSWs efficiently into spatial domains slightly smaller than half the wavelength. Selected examples of such functional elements are fabricated. Their ability to focus BSWs is experimentally verified by measuring the field distributions with a scanning near-field optical microscope. Our focusing elements are promising ingredients for a future generation of integrated photonic devices that rely on BSWs, e.g., to carry information, or lab-on-chip devices for specific sensing applications.
关键词： focusing elements,scanning near-field optical microscope,integrated photonic devices,Bloch surface waves,photonic design
更新于2025-09-04 15:30:14