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12 pages, 4747 KiB

Open AccessArticle

Semi-Analytical Approach versus Finite Element Method for Analysis of Propagation Properties in Rectangular Waveguides: Silica-Titania Technological Platform

by Bartosz Janaszek, Muhammad A. Butt and Ryszard Piramidowicz

Electronics 2024, 13(1), 73; https://doi.org/10.3390/electronics13010073 - 22 Dec 2023

Cited by 1 | Viewed by 1156

Abstract

This work explicitly demonstrates a semi-analytical effective index approximation (EIA) approach for the description of the propagation properties of rib and ridge waveguides. By using the example of waveguides realized on a low-cost silica-titania (SiO₂:TiO₂) technological platform, we present that EIA may be successfully applied for the approximate determination of modal effective indices and single mode propagation conditions. All obtained results have been confirmed to be convergent with the finite element method (FEM) simulations at low relative error. Due to the tremendously fast execution time of EIA simulations in comparison with the FEM solver, we believe that the presented approach may be applied in a preliminary step of designing functional blocks in new and existing photonic integrated circuit technologies, which often require complex and multi-parameter calculations. Full article

(This article belongs to the Special Issue Section Collection Series: Recent Advances in Optoelectronics from Lab to Industry)

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10 pages, 2092 KiB

Open AccessArticle

Racetrack Ring Resonator Integrated with Multimode Interferometer Structure Based on Low-Cost Silica–Titania Platform for Refractive Index Sensing Application

by Muhammad A. Butt, Muhammad Shahbaz and Ryszard Piramidowicz

Photonics 2023, 10(9), 978; https://doi.org/10.3390/photonics10090978 - 27 Aug 2023

Cited by 59 | Viewed by 2815

Abstract

In this work, a racetrack ring resonator (RTRR) integrated with a multimode interferometer (MMI) structure based on a silica–titania (SiO₂:TiO₂) platform is projected for refractive index sensing application. The typical ring resonator structure requires a gap of ~100 nm to 200 nm between the bus waveguide (WG) and the ring structure which makes it challenging to fabricate a precise device. Thus, the device proposed in this paper can be considered a “gapless” ring resonator structure in which the coupling of light between the ring and bus WG can be achieved via an MMI coupler. A minor change in the refractive index in the vicinity of the MMI structure can trigger a shift in the resonance wavelength of the device. Thus, this simple and fascinating structure can be employed as a refractive index sensor. The device’s sensitivity is ~142.5 nm/RIU in the refractive index range of 1.33 to 1.36 with a figure of merit (FOM) of 78.3. This simple device structure can potentially be fabricated via a low-cost and highly efficient sol–gel process and dip-coating method combined with the nanoimprint lithography (NIL) method. Full article

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10 pages, 2611 KiB

Open AccessArticle

Characteristics of Synaptic Function of Mesoporous Silica–Titania and Mesoporous Titania Lateral Electrode Devices

by Dhanashri Vitthal Desai, Jongmin Yang and Hyun Ho Lee

Nanomaterials 2023, 13(11), 1734; https://doi.org/10.3390/nano13111734 - 25 May 2023

Cited by 2 | Viewed by 1779

Abstract

In this paper, we have fabricated non-volatile memory resistive switching (RS) devices and analyzed analog memristive characteristics using lateral electrodes with mesoporous silica–titania (meso-ST) and mesoporous titania (meso-T) layers. For the planar-type device having two parallel electrodes, current–voltage (I–V) curves and pulse-driven current changes could reveal successful long-term potentiation (LTP) along with long-term depression (LTD), respectively, by the RS active mesoporous two layers for 20~100 μm length. Through mechanism characterization using chemical analysis, non-filamental memristive behavior unlike the conventional metal electroforming was identified. Additionally, high performance of the synaptic operations could be also accomplished such that a high current of 10⁻⁶ Amp level could occur despite a wide electrode spacing and short pulse spike biases under ambient condition with moderate humidity (RH 30~50%). Moreover, it was confirmed that rectifying characteristics were observed during the I–V measurement, which was a representative feature of dual functionality of selection diode and the analog RS device for both meso-ST and meso-T devices. The memristive and synaptic functions along with the rectification property could facilitate a chance of potential implementation of the meso-ST and meso-T devices to neuromorphic electronics platform. Full article

(This article belongs to the Special Issue Nanostructures for Integrated Devices)

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12 pages, 8720 KiB

Open AccessArticle

Silica-Titania Integrated Photonics Platform-Based 1 × 2 Demultiplexer Utilizing Two Serially Cascaded Racetrack Microrings for 1310 nm and 1550 nm Telecommunication Wavelengths

by Muhammad A. Butt, Muhammad Shahbaz, Łukasz Kozłowski, Andrzej Kaźmierczak and Ryszard Piramidowicz

Photonics 2023, 10(2), 208; https://doi.org/10.3390/photonics10020208 - 14 Feb 2023

Cited by 8 | Viewed by 2077

Abstract

Herein, a numerical analysis of a 1 × 2 demultiplexer based on a silica-titania integrated photonics platform is conducted via the finite element method. The structure is composed of two coupled racetrack microrings (RTMRs) and a subwavelength grating (SWG) structure for the demultiplexing of 1310 nm and 1550 nm telecommunication wavelengths. The material platform selected for this design is highly attractive due to its refined optical, physical, and chemical properties. Moreover, silica-titania sol-gel thin-films can be deposited on glass substrates with the dip-coating method. The proposed device has a small footprint of 84 × 125 μm² and offers crosstalk as low as ~−6.6 dB and ~−9.04 dB for 1550 nm and 1310 nm, respectively. We are convinced that this study promotes the use of the silica-titania platform for the development of low-cost on-chip optical communication devices for signal multiplexing and demultiplexing. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Photonics Sensors)

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25 pages, 2327 KiB

Open AccessReview

Optical Thin Films Fabrication Techniques—Towards a Low-Cost Solution for the Integrated Photonic Platform: A Review of the Current Status

by Muhammad A. Butt, Cuma Tyszkiewicz, Paweł Karasiński, Magdalena Zięba, Andrzej Kaźmierczak, Maria Zdończyk, Łukasz Duda, Malgorzata Guzik, Jacek Olszewski, Tadeusz Martynkien, Alicja Bachmatiuk and Ryszard Piramidowicz

Materials 2022, 15(13), 4591; https://doi.org/10.3390/ma15134591 - 29 Jun 2022

Cited by 31 | Viewed by 7441

Abstract

In the past few decades, several methods concerning optical thin films have been established to facilitate the development of integrated optics. This paper provides a brief depiction of different techniques for implementing optical waveguide thin films that involve chemical, physical, and refractive index modification methods. Recent advances in these fabrication methods are also been presented. Most of the methods developed for the realization of the thin-films are quite efficient, but they are expensive and require sophisticated equipment. The major interest of the scientists is to develop simple and cost-effective methods for mass production of optical thin films resulting in the effective commercialization of the waveguide technology. Our research group is focused on developing a silica-titania optical waveguide platform via the sol-gel dip-coating method and implementing active and passive optical elements via the wet etching method. We are also exploring the possibility of using nanoimprint lithography (NIL) for patterning these films so that the fabrication process is efficient and economical. The recent developments of this platform are discussed. We believe that silica-titania waveguide technology developed via the sol-gel dip-coating method is highly attractive and economical, such that it can be commercialized for applications such as sensing and optical interconnects. Full article

(This article belongs to the Special Issue Feature Papers in Thin Films and Interfaces)

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15 pages, 22662 KiB

Open AccessArticle

Subwavelength Grating Waveguide Structures Proposed on the Low-Cost Silica–Titania Platform for Optical Filtering and Refractive Index Sensing Applications

by Muhammad A. Butt, Cuma Tyszkiewicz, Katarzyna Wojtasik, Paweł Karasiński, Andrzej Kaźmierczak and Ryszard Piramidowicz

Int. J. Mol. Sci. 2022, 23(12), 6614; https://doi.org/10.3390/ijms23126614 - 14 Jun 2022

Cited by 19 | Viewed by 3125

Abstract

The sol–gel dip-coating method is a cost-efficient way for the realization of thin films on a planar substrate. In this work, high-quality, low-loss, and low-surface roughness silica–titania thin films are deposited on a glass substrate with the sol–gel dip-coating method. This platform works in the visible to near-IR wavelength ranges and can be useful for several eye-catching photonic components. The paper is comprised of two parts: the first part deals with the development of a low-cost silica–titania waveguide system, whereas the second part provides detail on the numerical modeling of the SWG waveguide filter and SWG waveguide FP-sensor design. The SWG waveguide NIR-stopband filter can achieve an ER of >40 dB and 3-dB bandwidth of 110 nm designed at optimized parameters. The SWG waveguide-FP structure proposed in this work act as a refractive index sensor where the sensitivity is ~120 nm/RIU by reducing the width of the waveguide. This sensitivity can be further enhanced by reducing the waveguide height. We believe that this work is quite important for the realization of low-cost integrated photonic devices based on the silica–titania platform developed via the sol–gel dip-coating method. Full article

(This article belongs to the Section Molecular Biophysics)

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14 pages, 3751 KiB

Open AccessArticle

Mode Sensitivity Exploration of Silica–Titania Waveguide for Refractive Index Sensing Applications

by Muhammad A. Butt, Andrzej Kaźmierczak, Cuma Tyszkiewicz, Paweł Karasiński and Ryszard Piramidowicz

Sensors 2021, 21(22), 7452; https://doi.org/10.3390/s21227452 - 9 Nov 2021

Cited by 19 | Viewed by 2806

Abstract

In this paper, a novel and cost-effective photonic platform based on silica–titania material is discussed. The silica–titania thin films were grown utilizing the sol–gel dip-coating method and characterized with the help of the prism-insertion technique. Afterwards, the mode sensitivity analysis of the silica–titania ridge waveguide is investigated via the finite element method. Silica–titania waveguide systems are highly attractive due to their ease of development, low fabrication cost, low propagation losses and operation in both visible and near-infrared wavelength ranges. Finally, a ring resonator (RR) sensor device was modelled for refractive index sensing applications, offering a sensitivity of 230 nm/RIU, a figure of merit (FOM) of 418.2 RIU⁻¹, and Q-factor of 2247.5 at the improved geometric parameters. We believe that the abovementioned integrated photonics platform is highly suitable for high-performance and economically reasonable optical sensing devices. Full article

(This article belongs to the Special Issue Selected Papers from 16th International Conference on Optical and Electronic Sensors (COE 2020))

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