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8 pages, 2419 KB

Open AccessArticle

Thermo-Tuning Fourier Transform Spectrometer Based on SU-8 Waveguide

by Qiongchan Shao, Xiao Ma, Mingyu Li and Jian-Jun He

Polymers 2025, 17(3), 261; https://doi.org/10.3390/polym17030261 - 21 Jan 2025

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On-chip Fourier transform spectrometer (FTS) is a promising technology due to the compact size, low cost, and relatively high throughput. In this work, we design, fabricate, and characterize a Mach-Zehnder interferometer (MZI) FTS based on SU-8 polymer waveguide. The optical path length difference of MZI is tuned by a heater with a maximum power consumption of 2.2 W. The interference signal is analyzed by Fourier transform algorithm, to retrieve the spectrum of light source. The footprint of the fabricated FTS device is only 2 × 12 mm², with the spectral bandwidth of ~100 nm and resolution <20 nm. Full article

(This article belongs to the Section Polymer Applications)

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11 pages, 3053 KB

Open AccessArticle

Silica–Polymer Heterogeneous Hybrid Integrated Mach–Zehnder Interferometer Optical Waveguide Temperature Sensor

by Zhanyu Gao, Yuhang Du, Qizheng Zhang, Yinxiang Qin, Jiongwen Fang and Yunji Yi

Polymers 2024, 16(16), 2297; https://doi.org/10.3390/polym16162297 - 14 Aug 2024

Cited by 2 | Viewed by 1383

Abstract

In this paper, a temperature sensor based on a polymer–silica heterogeneous integrated Mach–Zehnder interferometer (MZI) structure is proposed. The MZI structure consists of a polymer waveguide arm and a doped silica waveguide arm. Due to the opposite thermal optical coefficients of polymers and silica, the hybrid integrated MZI structure enhances the temperature sensing characteristics. The direct coupling method and side coupling method are introduced to reduce the coupling loss of the device. The simulation results show that the side coupling structure has lower coupling loss and greater manufacturing tolerance compared to the direct coupling structure. The side coupling loss for PMMA material-based devices, NOA material-based devices, and SU-8 material-based devices is 0.104 dB, 0.294 dB, and 0.618 dB, respectively. The sensitivity (S) values of the three hybrid devices are −6.85 nm/K, −6.48 nm/K, and −2.30 nm/K, which are an order of magnitude higher than those of an all-polymer waveguide temperature sensor. We calculated the temperature responsivity (R_T) (FSR→∞) of the three devices as 13.16 × 10⁻⁵ K, 32.20 × 10⁻⁵ K, and 20.20 × 10⁻⁵ K, suggesting that high thermo-optic coefficient polymer materials and the hybrid integration method have a promising application in the field of on-chip temperature sensing. Full article

(This article belongs to the Section Polymer Applications)

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26 pages, 534 KB

Open AccessReview

Sensitivity of Quantum-Enhanced Interferometers

by Dariya Salykina and Farid Khalili

Symmetry 2023, 15(3), 774; https://doi.org/10.3390/sym15030774 - 22 Mar 2023

Cited by 8 | Viewed by 3506

Abstract

We review various schemes of quantum-enhanced optical interferometers, both linear (SU(2)) and non-linear (SU(1,1)) ones, as well as hybrid SU(2)/SU(1,1) options, using the unified modular approach based on the Quantum Cramèr–Rao bound (QCRB), and taking into account the practical limitations pertinent to all real-world highly-sensitive interferometers. We focus on three important cases defined by the interferometer symmetry: (i) the asymmetric single-arm interferometer; (ii) the symmetric two-arm interferometer with the antisymmetric phase shifts in the arms; and (iii) the symmetric two-arm interferometer with the symmetric phase shifts in the arms. We show that while the optimal regimes for these cases differ significantly, their QCRBs asymptotically correspond to the same squeezing-enhanced shot noise limit (2), which first appeared in the pioneering work by C. Caves in 1981.We show also that in all considered cases the QCRB can be asymptotically saturated by the standard (direct or homodyne) detection schemes. Full article

(This article belongs to the Special Issue Quantum Mechanics and Symmetry/Asymmetry: Review Paper on Quantum Nonlinear Interferometers)

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26 pages, 9142 KB

Open AccessReview

Phase Sensitivity Improvement in Correlation-Enhanced Nonlinear Interferometers

by Xinyun Liang, Zhifei Yu, Chun-Hua Yuan, Weiping Zhang and Liqing Chen

Symmetry 2022, 14(12), 2684; https://doi.org/10.3390/sym14122684 - 19 Dec 2022

Cited by 10 | Viewed by 4013

Abstract

Interferometers are widely used as sensors in precision measurement. Compared with a conventional Mach–Zehnder interferometer, the sensitivity of a correlation-enhanced nonlinear interferometer can break the standard quantum limit. Phase sensitivity plays a significant role in the enhanced performance. In this paper, we review improvement in phase estimation technologies in correlation-enhanced nonlinear interferometers, including SU(1,1) interferometer and SU(1,1)-SU(2) hybrid interferometer, and so on, and the applications in quantum metrology and quantum sensing networks. Full article

(This article belongs to the Special Issue Quantum Mechanics and Symmetry/Asymmetry: Review Paper on Quantum Nonlinear Interferometers)

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12 pages, 485 KB

Open AccessArticle

Two-Colour Spectrally Multimode Integrated SU(1,1) Interferometer

by Alessandro Ferreri and Polina R. Sharapova

Symmetry 2022, 14(3), 552; https://doi.org/10.3390/sym14030552 - 9 Mar 2022

Cited by 2 | Viewed by 3023

Abstract

Multimode integrated interferometers have great potential for both spectral engineering and metrological applications. However, the material dispersion of integrated platforms constitutes an obstacle that limits the performance and precision of such interferometers. At the same time, two-colour nonlinear interferometers present an important tool for metrological applications, when measurements in a certain frequency range are difficult. In this manuscript, we theoretically developed and investigated an integrated multimode two-colour SU(1,1) interferometer operating in a supersensitive mode. By ensuring the proper design of the integrated platform, we suppressed the dispersion, thereby significantly increasing the visibility of the interference pattern. The use of a continuous wave pump laser provided the symmetry between the spectral shapes of the signal and idler photons concerning half the pump frequency, despite different photon colours. We demonstrate that such an interferometer overcomes the classical phase sensitivity limit for wide parametric gain ranges, when up to

3 \times 10^{4}

photons are generated. Full article

(This article belongs to the Section Physics)

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11 pages, 4734 KB

Open AccessArticle

Trimodal Waveguide Demonstration and Its Implementation as a High Order Mode Interferometer for Sensing Application

by Jhonattan C. Ramirez, Lucas H. Gabrielli, Laura M. Lechuga and Hugo E. Hernandez-Figueroa

Sensors 2019, 19(12), 2821; https://doi.org/10.3390/s19122821 - 24 Jun 2019

Cited by 15 | Viewed by 3932

Abstract

This work implements and demonstrates an interferometric transducer based on a trimodal optical waveguide concept. The readout signal is generated from the interference between the fundamental and second-order modes propagating on a straight polymer waveguide. Intuitively, the higher the mode order, the larger the fraction of power (evanescent field) propagating outside the waveguide core, hence the higher the sensitivity that can be achieved when interfering against the strongly confined fundamental mode. The device is fabricated using the polymer SU-8 over a SiO₂ substrate and shows a free spectral range of 20.2 nm and signal visibility of 5.7 dB, reaching a sensitivity to temperature variations of 0.0586 dB/°C. The results indicate that the proposed interferometer is a promising candidate for highly sensitive, compact and low-cost photonic transducer for implementation in different types of sensing applications, among these, point-of-care. Full article

(This article belongs to the Section Optical Sensors)

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10 pages, 2754 KB

Open AccessFeature PaperArticle

Optical Fiber-Tip Sensors Based on In-Situ µ-Printed Polymer Suspended-Microbeams

by Mian Yao, Xia Ouyang, Jushuai Wu, A. Ping Zhang, Hwa-Yaw Tam and P. K. A. Wai

Sensors 2018, 18(6), 1825; https://doi.org/10.3390/s18061825 - 5 Jun 2018

Cited by 28 | Viewed by 7076

Abstract

Miniature optical fiber-tip sensors based on directly µ-printed polymer suspended-microbeams are presented. With an in-house optical 3D μ-printing technology, SU-8 suspended-microbeams are fabricated in situ to form Fabry–Pérot (FP) micro-interferometers on the end face of standard single-mode optical fiber. Optical reflection spectra of the fabricated FP micro-interferometers are measured and fast Fourier transform is applied to analyze the cavity of micro-interferometers. The applications of the optical fiber-tip sensors for refractive index (RI) sensing and pressure sensing, which showed 917.3 nm/RIU to RI change and 4.29 nm/MPa to pressure change, respectively, are demonstrated in the experiments. The sensors and their optical µ-printing method unveil a new strategy to integrate complicated microcomponents on optical fibers toward ‘lab-on-fiber’ devices and applications. Full article

(This article belongs to the Special Issue Lab on Fiber Optrodes for Chemical and Biological Sensing: Recent Trends and Advances)

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