Theoretical modeling and numerical simulation have been performed at λ=2100 nm on silicon-on-insulator channel-waveguide directional couplers in which the outer two Si waveguides are passive and the central waveguide(s) are electro-optical (EO) "islands." The EO channel(s) utilize a 10 nm layer of Ge2Sb2Te5 phase-change-material sited at midlevel of a doped Si channel. A voltage-driven phase change produces a large change in the effective index of the TE(o) and TM(o) modes, thereby inducing crossbar 2×2 switching. A mode-matching method is employed to estimate EO switching performance in the limit of strong interguide coupling. Low-loss switching is predicted for cross-to-bar and bar-to-cross coupling lengths. These "self-holding" switches had active lengths of 500-1000 μm, which are shorter than those in couplers relying upon free-carrier injection. The four-waveguide devices had lower cross talk but higher loss than the three-waveguide devices. For the crystalline phase we sometimes used an active length that was smaller than that for the amorphous phase.
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http://dx.doi.org/10.1364/AO.54.005897 | DOI Listing |
Npj Nanophoton
January 2025
Department of Physics, Humboldt-Universität zu Berlin, Berlin, Germany.
We introduce a novel material for integrated photonics and investigate aluminum gallium nitride (AlGaN) on aluminum nitride (AlN) templates as a platform for developing reconfigurable and on-chip nonlinear optical devices. AlGaN combines compatibility with standard photonic fabrication technologies and high electro-optic modulation capabilities with low loss over a broad spectral range, from UVC to long-wave infrared, making it a viable material for complex photonic applications. In this work, we design and grow AlGaN/AlN heterostructures and integrate several photonic components.
View Article and Find Full Text PDFSci Adv
January 2025
Institute of Physics, University of Rostock, Rostock, Germany.
Exceptional points facilitate peculiar dynamics in non-Hermitian systems. Yet, in photonics, they have mainly been studied in the classical realm. In this work, we reveal the behavior of two-photon quantum states in non-Hermitian systems across the exceptional point.
View Article and Find Full Text PDFSci Rep
January 2025
Departemant of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
With careful design and integration, microring resonators can serve as a promising foundation for developing compact and scalable sources of non-classical light for quantum information processing. However, the current design flow is hindered by computational challenges and a complex, high-dimensional parameter space with interdependent variables. In this work, we present a knowledge-integrated machine learning framework based on Bayesian Optimization for designing squeezed light sources using microring resonators.
View Article and Find Full Text PDFGrating-assisted, contra-directional couplers (GA-CDCs), owing to their four-port operations, can offer several important advantages over traditional, single waveguide-based Bragg gratings. However, how to flexibly design the spectral responses of GA-CDCs has been much less studied. We report the spectral tailoring methodology of GA-CDCs to achieve arbitrary, physically realizable, complex spectral responses.
View Article and Find Full Text PDFNanophotonics
September 2024
State Key Laboratory for Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Center for Optical & Electromagnetic Research, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
Efficient coupling between optical fibers and on-chip photonic waveguides has long been a crucial issue for photonic chips used in various applications. Edge couplers (ECs) based on an inverse taper have seen widespread utilization due to their intrinsic broadband operation. However, it still remains a big challenge to realize polarization-insensitive low-loss ECs working at the O-band (1,260-1,360 nm), mainly due to the strong polarization dependence of the mode coupling/conversion and the difficulty to fabricate the taper tip with an ultra-small feature size.
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