المؤلفون: Fujiwara, Eric, Oku, Hiromasa, Cordeiro, Cristiano M. B.

المصدر: MRS Communications; Jun2024, Vol. 14 Issue 3, p237-247, 11p

مصطلحات موضوعية: OPTICAL devices, RED algae, OPTICAL fibers, EDIBLE coatings, OPTICS, WAVEGUIDES

مستخلص: Biocompatible optical devices are breakthrough illumination, imaging, and biomedical sensing technologies. Despite the noteworthy developments in silk, cellulose, and hydrogel-based optics, such approaches rely on expensive precursors and intricate fabrication. Therefore, agar extracted from red algae emerges as a promising biodegradable alternative as an edible, low-cost, and renewable material. This paper overviews the state-of-the-art of agar-based optical devices. Firstly, we revisit this phycocolloid's fundamentals and highlight its appealing mechanical, optical, and electrical characteristics. Subsequently, we summarize the available agar elements, slab waveguides, and optical fibers. Lastly, we discuss their advantages and challenges by envisaging opportunities for future developments and applications. [ABSTRACT FROM AUTHOR]

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المؤلفون: Arcadio, Francesco¹ (AUTHOR) francesco.arcadio@unicampania.it, Marzano, Chiara¹ (AUTHOR), Del Prete, Domenico¹ (AUTHOR), Zeni, Luigi¹ (AUTHOR), Cennamo, Nunzio¹ (AUTHOR) nunzio.cennamo@unicampania.it

المصدر: Sensors (14248220). Jul2023, Vol. 23 Issue 13, p6182. 12p.

مصطلحات موضوعية: *PLASTIC optical fibers, *SURFACE plasmon resonance, *OPTICAL waveguides, *REFRACTIVE index, *PLASMONICS, *DETECTORS, *ADHESIVES, *WAVEGUIDES

مستخلص: Polymer-based surface plasmon resonance (SPR) sensors can be used to realize simple, small-size, disposable, and low-cost biosensors for application in several fields, e.g., healthcare. The performance of SPR sensors based on optical waveguides can be changed by tuning several parameters, such as the dimensions and the shape of the waveguides, the refractive index of the core, and the metal nanofilms used to excite the SPR phenomenon. In this work, in order to develop, experimentally test, and compare several polymer-based plasmonic sensors, realized by using waveguides with different core refractive indices, optical adhesives and 3D printed blocks with a trench inside have been used. In particular, the sensors are realized by filling the blocks' trenches (with two plastic optical fibers located at the end of these) with different UV-cured optical adhesives and then covering them with the same bilayer to excite the SPR phenomenon. The developed SPR sensors have been characterized by numerical and experimental results. Finally, in order to propose photonic solutions for healthcare, a comparative analysis has been reported to choose the best sensor configuration useful for developing low-cost biosensors. [ABSTRACT FROM AUTHOR]

المؤلفون: Jin, Yingying¹ (AUTHOR), Yang, Liu¹ (AUTHOR), Huang, Yishu¹ (AUTHOR), Yang, Yuxin¹ (AUTHOR), Wang, Pan^1,2,3 (AUTHOR), Dai, Daoxin¹ (AUTHOR), Guo, Xin^1,2,3 (AUTHOR) guoxin@zju.edu.cn, Tong, Limin^1,4 (AUTHOR) phytong@zju.edu.cn

المصدر: Laser & Photonics Reviews. Jun2023, Vol. 17 Issue 6, p1-7. 7p.

مصطلحات موضوعية: *OPTICAL interconnects, *SINGLE-mode optical fibers, *NANOWIRES, *WAVEGUIDES

مستخلص: An efficient fiber‐to‐chip interface via an intermediated CdS nanowire is demonstrated. The fiber mode is firstly squeezed through a fiber taper drawn at the end of a single‐mode fiber, then evanescently coupled into an intermediated CdS nanowire with a longitudinally tapering profile, and finally coupled into an on‐chip silicon waveguide (SiW) via a waveguide taper fabricated on it. Since the fiber‐nanowire‐SiW cascade structure is designed to match effective indices in each coupling area, such a fiber‐to‐chip interface ensures a bidirectional coupling efficiency up to 90% and a 3‐dB bandwidth over 100 nm in experiments. The difference of coupling efficiencies between the TM or TE modes is less than 0.5 dB in the spectral range of 1545–1635 nm. The footprint of the on‐chip coupling structure is about 10 µm in size. The results may provide a compact, efficient, and versatile fiber‐to‐chip interface in applications including optical interconnects, coherent communication, and quantum optical circuitry. [ABSTRACT FROM AUTHOR]

المؤلفون: Parker, Ross¹ (AUTHOR) rhparker@smu.edu, Shen, Yannan² (AUTHOR), Aceves, Alejandro¹ (AUTHOR), Zweck, John³ (AUTHOR)

المصدر: Studies in Applied Mathematics. Aug2022, Vol. 149 Issue 2, p537-560. 24p.

مصطلحات موضوعية: OPTICAL fibers, NONLINEAR Schrodinger equation, LIGHT intensity, NONLINEAR optics, WAVEGUIDES

مستخلص: We consider the existence and spectral stability of nonlinear discrete localized solutions representing light pulses propagating in a twisted multicore optical fiber. By considering an even number, N, of waveguides, we derive asymptotic expressions for solutions in which the bulk of the light intensity is concentrated as soliton‐like pulses confined to a single waveguide. The leading order terms obtained are in very good agreement with results of numerical computations. Furthermore, as in the model without temporal dispersion, when the twist parameter, ϕ, is given by ϕ=π/N$\phi = \pi/N$, these standing waves exhibit optical suppression, in which a single waveguide remains unexcited, to leading order. Spectral computations and numerical evolution experiments suggest that these standing wave solutions are stable for values of the coupling parameter less than a critical value, at which point a spectral instability results from the collision of an internal eigenvalue with the eigenvalues at the origin. This critical value has a maximum when ϕ=π/N$\phi = \pi/N$. [ABSTRACT FROM AUTHOR]

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المؤلفون: Lin, Chung-Chih, Na, Audrey, Wu, Yi-Kuei, Wang, Likarn, Na, Neil

المصدر: Photonics; Mar2024, Vol. 11 Issue 3, p267, 11p

مصطلحات موضوعية: OPTICAL gratings, COVARIANCE matrices, WAVEGUIDES, SINGLE-mode optical fibers, ELECTRON beams, LITHOGRAPHY, DEEP learning

مستخلص: Grating couplers are essential components in silicon photonics that facilitate the coupling of light between waveguides and fibers. Optimization of the grating couplers to reach <1 dB loss when coupling to single-mode fibers (SMFs) has been reported in the literature, but this was based on silicon-on-insulator (SOI) waveguides supporting multi-modes. In this paper, using a deep-learning model combined with an inverse-design process, we achieve <1 dB losses for grating couplers implemented over single-mode SOI waveguides, i.e., a maximum efficiency of 80.5% (−0.94 dB) for gratings constrained with e-beam (EB) lithography critical dimension (CD), and a maximum efficiency of 77.9% (−1.09 dB) for gratings constrained with deep ultraviolet (DUV) lithography CD. To verify these results, we apply covariance matrix adaptation evolution strategy (CMA-ES) and find that while CMA-ES yields slightly better results, i.e., 82.7% (−0.83 dB) and 78.9% (−1.03 dB) considering e-beam and DUV, respectively, the spatial structures generated by CMA-ES are nearly identical to the spatial structures generated by the deep-learning model combined with the inverse-design process. This suggests that our approach can achieve a representative low-loss structure, and may be used to improve the performance of other types of nanophotonic devices in the future. [ABSTRACT FROM AUTHOR]

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المؤلفون: De Gregorio, Marco, Yu, Shangxuan, Witt, Donald, Lin, Becky, Mitchell, Matthew, Dusanowski, Łukasz, Schneider, Christian, Chrostowski, Lukas, Huber‐Loyola, Tobias, Höfling, Sven, Young, Jeff F., Pfenning, Andreas

المصدر: Advanced Quantum Technologies; Jan2024, Vol. 7 Issue 1, p1-7, 7p

مصطلحات موضوعية: QUANTUM dots, OPTICAL fibers, PHOTONS, WIRE, PHOTONIC crystal fibers, WAVEGUIDES, RESONANT tunneling

مستخلص: The collection of single‐photon emission from a quantum dot (QD) in a Bragg waveguide through a photonic wire bond (PWB) via free‐space resonant frequency pumping at 1.6 K is demonstrated. The in‐fiber single photons show a small multiphoton contribution, quantified by a low second order photon autocorrelation value of gcorr(2)(0)=(5.9±0.8)×10−3$g_{{\mathrm{corr}}}^{(2)}\;(0) = ({5.9 \pm 0.8})\; \times {10^{ - 3}}$ (background‐corrected) or graw(2)(0)=(9.5±1.4)×10−2$g_{{\mathrm{raw}}}^{(2)}(0)\; = ({9.5 \pm 1.4})\; \times {10^{ - 2}}{\mathrm{\;}}$(raw data). The decay time of the QD is measured to be τ=440${\mathrm{\tau \;}} = {\mathrm{\;}}440$ ps. The PWB obviates the need for in‐cryostat alignment of the single‐photon source with an optical fiber and thus offers a route to scalable integration of quantum photonic devices in a cryogenic environment. Uniquely, the approach combines the QD‐waveguide technique, enabling resonant driving of individual QDs without the need for cross‐polarization filtering, and the PWB for deterministic, alignment‐free coupling of single‐photon sources to optical fibers. [ABSTRACT FROM AUTHOR]

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المؤلفون: Ertman, Sławomir, Orzechowski, Kamil, Rutkowska, Katarzyna, Kołodyńska, Oliwia, Różycka, Julia, Ignaciuk, Adam, Wasilewska, Natalia, Osuch, Tomasz, Woliński, Tomasz R.

المصدر: Scientific Reports; 11/20/2023, Vol. 13 Issue 1, p1-15, 15p

مصطلحات موضوعية: OPTICAL gratings, OPTICAL waveguides, MICROSTRUCTURE, OPTICAL spectra, WAVEGUIDES, OPTICAL fibers, MICROELECTRODES

مستخلص: Different methods allowing for creating optical waveguides with liquid–crystal (LC) cores, in which molecules form periodic patterns with precisely controlled periods, are reported. The first one is based on reversible photoalignment with high-resolution selective illumination and allows to control the period of LC molecules inside silica microcapillaries. The second method employs microstructures formed in PDMS, allowing to obtain both: LC-core waveguides and a set of specially designed periodic microelectrodes used for the periodic reorientation of molecules. Using both methods, we successfully controlled the period of the patterned alignment in the range from about 500 µm and scaled it down to as small as 20 µm. We performed experimental studies on waveguiding phenomenon in such structures, in view to obtain transmission spectra typical to optical fiber gratings. Since the results achieved in experimental conditions differed from those expected, the additional numerical simulations were performed to explain the observed effects. Finally, we obtained the waveguiding in a blue phase LC, characterized by naturally created three-dimensional periodicity with periods smaller than one micrometer. In such a structure, we were able to observe first-order bandgap, and moreover, we were able to tune it thermally in nearly the whole visible spectral range. [ABSTRACT FROM AUTHOR]

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المؤلفون: Parfenov, M. V., Agruzov, P. M., Ilichev, I. V., Usikova, A. A., Shamrai, A. V.

المصدر: Technical Physics; Nov2023, Vol. 68 Issue 11, p443-447, 5p

مصطلحات موضوعية: WAVEGUIDES, TITANIUM dioxide, SINGLE-mode optical fibers, SILICA, LITHIUM niobate, FIBERS, INTEGRATED optics

مستخلص: Topology of a hybrid waveguide device, which performs an effective transformation of a standard gradient titanium in-diffused waveguide mode to a hybrid waveguide mode, is considered. With its help a rather large optical mode with size optimal for coupling with standard single-mode fibers can be converted to a mode with a smaller size. Two the most perspective materials for hybrid waveguide fabrication were considered: silicon and titanium dioxide. The theoretical analysis has shown that transformation efficiency of more than 99% is achievable for waveguide devices based on titanium dioxide with contact lithography resolution. [ABSTRACT FROM AUTHOR]

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المؤلفون: Ohana, Eli, Malka, Dror

المصدر: Applied Sciences (2076-3417); Sep2023, Vol. 13 Issue 17, p9951, 13p

مصطلحات موضوعية: SILICON nitride, INTEGRATED circuits, SINGLE-mode optical fibers, WAVEGUIDES

مستخلص: To test silicon photonics component performances, a silicon (Si) grating coupler (GC) is used to couple the light from a single-mode fiber (SMF) into the chip. However, silicon nitride (Si3N4) waveguides have recently become more popular for realizing photonic integrated circuits (PICs), which may be attributable to their exceptional characteristics, such as minimal absorption and low back reflection (BR) in the O-band spectrum. Thus, to test the photonic chip, a waveguide converter from Si3N4 to Si needs to be added to the photonic circuit, which can lead to more power losses and BR. To avoid this conversion, we propose in this manuscript a configuration of a GC based on Si3N4 structures, which can be employed to minimize the footprint size and obtain better performance. The achievement of high efficiency was possibly obtained by optimizing the structural properties of the waveguide and the coupling angle from the SMF. The results demonstrated high efficiency within the O-band spectrum by using a wavelength of 1310 nm. Notably, at this specific wavelength, the findings indicated a coupling efficiency of −5.52 db. The proposed design of the GC consists of a uniform grating that offers improvements regarding affordability and simplicity in manufacturing compared to other GC models. For instance, using a reflector or a GC with non-uniform grooved teeth introduces challenges in fabrication and incurs higher costs. Thus, the proposed design can be useful for improving the testing abilities of the Si3N4 photonic chips used in transceiver systems. [ABSTRACT FROM AUTHOR]

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العنوان البديل: Вплив ключових параметрів на ефективність зв’язку лінійного переходу між оптичним волокном і хвилеводом для телекомунікаційних мереж. (Ukrainian)

المؤلفون: Khaldouna, Zahia, Brik, Fatima

المصدر: Journal of Nano- & Electronic Physics; 2023, Vol. 15 Issue 5, p05017-1-05017-5, 5p

مصطلحات موضوعية: TELECOMMUNICATION systems, OPTICAL fibers, WAVEGUIDES

مستخلص: This study focuses on the optimization of a lateral transition that is designed for coupling an optical fiber and a waveguide. The objective is to study the impact of the key parameters of this linear transition on the coupling efficiency, taking into consideration the index variations, the length, and the transition form, in order to improve the transmission performance without losses between the optic fiber and the waveguide. We accomplish this using BeamProb of Rsoft CAD, which relies on the Beam Propagation Method BPM. Besides, we carried out simulations of different shapes and lengths of the lateral transition. The findings of the simulations allowed for the analysis and evaluation of the different configurations of the lateral transition. In order to use this type of transition in the field of optic communications, we examined how the diverse intensities varied in the outlet and inlet of the taper. In addition, the results allow determining the suitable length and form of the taper where the signal is most exploitable. [ABSTRACT FROM AUTHOR]

: Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)