Sensors

Editorial

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4 pages, 182 KiB

Open AccessEditorial

Special Issue on Enabling Technology in Optical Fiber Communications: From Device, System to Networking

by Yang Yue, Jian Zhao, Jiangbing Du and Zhaohui Li

Sensors 2021, 21(6), 1969; https://doi.org/10.3390/s21061969 - 11 Mar 2021

Cited by 1 | Viewed by 1873

Abstract

It is well known that optical fiber communications support the global communication networks nowadays, which originates from Charles K [...] Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

Research

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19 pages, 3306 KiB

Open AccessArticle

Time-Domain Blind ICI Compensation in Coherent Optical FBMC/OQAM System

by Binqi Wu, Jin Lu, Mingyi Gao, Hongliang Ren, Zichun Le, Yali Qin, Shuqin Guo and Weisheng Hu

Sensors 2020, 20(21), 6397; https://doi.org/10.3390/s20216397 - 9 Nov 2020

Cited by 3 | Viewed by 3724

Abstract

A blind discrete-cosine-transform-based phase noise compensation (BD-PNC) is proposed to compensate the inter-carrier-interference (ICI) in the coherent optical offset-quadrature amplitude modulation (OQAM)-based filter-bank multicarrier (CO-FBMC/OQAM) transmission system. Since the phase noise sample can be approximated by an expansion of the discrete cosine transform [...] Read more.

A blind discrete-cosine-transform-based phase noise compensation (BD-PNC) is proposed to compensate the inter-carrier-interference (ICI) in the coherent optical offset-quadrature amplitude modulation (OQAM)-based filter-bank multicarrier (CO-FBMC/OQAM) transmission system. Since the phase noise sample can be approximated by an expansion of the discrete cosine transform (DCT) in the time-domain, a time-domain compensation model is built for the transmission system. According to the model, phase noise compensation (PNC) depends only on its DCT coefficients. The common phase error (CPE) compensation is firstly performed for the received signal. After that, a pre-decision is made on a part of compensated signals with low decision error probability, and the pre-decision results are used as the estimated values of transmitted signals to calculate the DCT coefficients. Such a partial pre-decision process reduces not only decision error but also the complexity of the BD-PNC method while keeping almost the same performance as in the case of the pre-decision of all compensated signals. Numerical simulations are performed to evaluate the performance of the proposed scheme for a 30 GBaud CO-FBMC/OQAM system. The simulation results show that its bit error rate (BER) performance is improved by more than one order of magnitude through the mitigation of the ICI in comparison with the traditional blind PNC scheme only aiming for CPE compensation. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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19 pages, 3099 KiB

Open AccessArticle

Hybrid Routing, Modulation, Spectrum and Core Allocation Based on Mapping Scheme

by Edson Rodrigues, Eduardo Cerqueira, Denis Rosário and Helder Oliveira

Sensors 2020, 20(21), 6393; https://doi.org/10.3390/s20216393 - 9 Nov 2020

Cited by 4 | Viewed by 2471

Abstract

With the persistently growing popularity of internet traffic, telecom operators are forced to provide high-capacity, cost-efficient, and performance-adaptive connectivity solutions to fulfill the requirements and increase their returns. However, optical networks that make up the core of the Internet gradually reached physical transmission [...] Read more.

With the persistently growing popularity of internet traffic, telecom operators are forced to provide high-capacity, cost-efficient, and performance-adaptive connectivity solutions to fulfill the requirements and increase their returns. However, optical networks that make up the core of the Internet gradually reached physical transmission limits. In an attempt to provide new solutions emerged, the Space-Division Multiplexing Elastic Optical Network emerged as one of the best ways to deal with the network depletion. However, it is necessary to establish lightpaths using routing, modulation, spectrum, and core allocation (RMSCA) algorithms to establish connections in these networks. This article proposes a crosstalk-aware RMSCA algorithm that uses a multi-path and mapping scheme for improving resource allocation. The results show that the proposed algorithm decreases the blocking ratio by up to four orders of magnitude compared with other RMSCA algorithms in the literature. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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13 pages, 1317 KiB

Open AccessArticle

Invalid-Resource-Aware Spectrum Assignment for Advanced-Reservation Traffic in Elastic Optical Network

by Shufang He, Yang Qiu and Jing Xu

Sensors 2020, 20(15), 4190; https://doi.org/10.3390/s20154190 - 28 Jul 2020

Cited by 15 | Viewed by 2706

Abstract

Elastic optical networks (EONs) can make service accommodation more flexible and precise by employing efficient routing and spectrum allocation (RSA) algorithms. In order to improve the efficiency of RSA algorithms, the advanced-reservation technique was introduced into designing RSA algorithms. However, few of these [...] Read more.

Elastic optical networks (EONs) can make service accommodation more flexible and precise by employing efficient routing and spectrum allocation (RSA) algorithms. In order to improve the efficiency of RSA algorithms, the advanced-reservation technique was introduced into designing RSA algorithms. However, few of these advanced-reservation-based RSA algorithms were focused on the unavailable spectrum resources in EONs. In this paper, we propose an Advanced-Reservation-based Invalid-Spectrum-Aware (AR-ISA) resource allocation algorithm to improve the networking performance and the resource alignment of EONs. By employing a new index, Invalid Spectrum Rate (ISR), to record the proportion of unavailable spectrum resources in EONs, the proposed AR-ISA algorithm set a network load threshold to trigger the postponement of an arriving service. Compared with the traditional slack-based AR mechanism, the proposed algorithm has more concerns about the current spectrum usage of the path designated by the service than the conflicts between AR services and other existing services. To further increase the networking performance, the proposed algorithm adopts defragmentation to increase the number of available spectrum resources when postponing a service. Theoretical analysis and simulation results show that the proposed AR-ISA algorithm has obvious effectiveness in reducing the service blocking rate and increasing the spectrum alignment rate. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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16 pages, 3870 KiB

Open AccessArticle

Impact of Equalization-Enhanced Phase Noise on Digital Nonlinearity Compensation in High-Capacity Optical Communication Systems

by Jiazheng Ding, Tianhua Xu, Cenqin Jin, Ziyihui Wang, Jian Zhao and Tiegen Liu

Sensors 2020, 20(15), 4149; https://doi.org/10.3390/s20154149 - 26 Jul 2020

Cited by 5 | Viewed by 3194

Abstract

Equalization-enhanced phase noise (EEPN) can severely degrade the performance of long-haul optical fiber transmission systems. In this paper, the impact of EEPN in Nyquist-spaced dual-polarization quadrature phase shift keying (DP-QPSK), dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM), and DP-64QAM optical transmission systems is investigated [...] Read more.

Equalization-enhanced phase noise (EEPN) can severely degrade the performance of long-haul optical fiber transmission systems. In this paper, the impact of EEPN in Nyquist-spaced dual-polarization quadrature phase shift keying (DP-QPSK), dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM), and DP-64QAM optical transmission systems is investigated considering the use of electrical dispersion compensation (EDC) and multi-channel digital backpropagation (MC-DBP). Our results demonstrate that full-field DBP (FF-DBP) is more susceptible to EEPN compared to single-channel and partial-bandwidth DBP. EEPN-induced distortions become more significant with the increase of the local oscillator (LO) laser linewidth, and this results in degradations in bit-error-rates (BERs), achievable information rates (AIRs), and AIR-distance products in optical communication systems. Transmission systems using higher-order modulation formats can enhance information rates and spectral efficiencies, but will be more seriously degraded by EEPN. It is found that degradations on AIRs, for the investigated FF-DBP schemes, in the DP-QPSK, the DP-16QAM, and the DP-64QAM systems are 0.07 Tbit/s, 0.11 Tbit/s, and 0.57 Tbit/s, respectively, due to the EEPN with an LO laser linewidth of 1 MHz. It is also seen that the selection of a higher-quality LO laser can significantly reduce the bandwidth requirement and the computational complexity in the MC-DBP. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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12 pages, 5826 KiB

Open AccessArticle

A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser

by Jiewei Yang, Tianxin Yang, Zhaoying Wang, Dongfang Jia and Chunfeng Ge

Sensors 2020, 20(14), 3834; https://doi.org/10.3390/s20143834 - 9 Jul 2020

Cited by 8 | Viewed by 4486

Abstract

Ultrafast linear frequency modulated continuous-wave (FMCW) lasers are a special category of CW lasers. The linear FMCW laser is the light source for many sensing applications, especially for light detection and ranging (LiDAR). However, systems for the generation of high quality linear FMCW [...] Read more.

Ultrafast linear frequency modulated continuous-wave (FMCW) lasers are a special category of CW lasers. The linear FMCW laser is the light source for many sensing applications, especially for light detection and ranging (LiDAR). However, systems for the generation of high quality linear FMCW light are limited and diverse in terms of technical approaches and mechanisms. Due to a lack of characterization methods for linear FMCW lasers, it is difficult to compare and judge the generation systems in the same category. We propose a novel scheme for measuring the mapping relationship between instantaneous frequency and time of a FMCW laser based on a modified coherent optical spectrum analyzer (COSA) and digital signal processing (DSP) method. Our method has the potential to measure the instantaneous frequency of a FMCW laser at an unlimited sweep rate. In this paper, we demonstrate how to use this new method to precisely measure a FMCW laser at a large fast sweep rate of 5000 THz/s by both simulation and experiments. We find experimentally that the uncertainty of this method is less than 100 kHz and can be improved further if a frequency feedback servo system is introduced to stabilize the local CW laser. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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16 pages, 3248 KiB

Open AccessArticle

A QoE-Aware Energy Supply Scheme over a FiWi Access Network in the 5G Era

by Chao He and Ruyan Wang

Sensors 2020, 20(13), 3794; https://doi.org/10.3390/s20133794 - 7 Jul 2020

Cited by 3 | Viewed by 3587

Abstract

Integrated fiber-wireless (FiWi) should be regarded as a promising access network architecture in future 5G networks, and beyond; this due to its seamless combination of flexibility, ubiquity, mobility of the wireless mesh network (WMN) frontend with a large capacity, high bandwidth, strong robustness [...] Read more.

Integrated fiber-wireless (FiWi) should be regarded as a promising access network architecture in future 5G networks, and beyond; this due to its seamless combination of flexibility, ubiquity, mobility of the wireless mesh network (WMN) frontend with a large capacity, high bandwidth, strong robustness in time, and a wavelength-division multiplexed passive optical network (TWDM-PON) backhaul. However, the key issue in both traditional human-to-human (H2H) traffic and emerging Tactile Internet is the energy conservation network operation. Therefore, a power-saving method should be instrumental in the wireless retransmission-enabled architecture design. Toward this end, this paper firstly proposes a novel energy-supply paradigm of the FiWi converged network infrastructure, i.e., the emerging power over fiber (PoF) technology instead of an external power supply. Then, the existing time-division multiplexing access (TDMA) scheme and PoF technology are leveraged to carry out joint dynamic bandwidth allocation (DBA) and provide enough power for the sleep schedule in each integrated optical network unit mesh portal point (ONU-MPP) branch. Additionally, the correlation between the transmitted optical power of the optical line terminal (OLT) and the quality of experience (QoE) guarantee caused by multiple hops in the wireless frontend is taken into consideration in detail. The research results prove that the envisioned paradigm can significantly reduce the energy consumption of the whole FiWi system while satisfying the average delay constraints, thus providing enough survivability for multimode optical fiber. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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14 pages, 2739 KiB

Open AccessArticle

Bipolar Optical Code Division Multiple Access Techniques Using a Dual Electro-Optical Modulator Implemented in Free-Space Optics Communications

by Shin-Pin Tseng, Eddy Wijanto, Po-Han Lai and Hsu-Chih Cheng

Sensors 2020, 20(12), 3583; https://doi.org/10.3390/s20123583 - 24 Jun 2020

Cited by 7 | Viewed by 3075

Abstract

This study developed a bipolar optical code division multiple access (Bi-OCDMA) technique based on spectral amplitude coding for the formation and transmission of optical-polarized and coded signals over wireless optical channels. Compared with conventional Bi-OCDMA schemes, the proposed free-space optics communication system that [...] Read more.

This study developed a bipolar optical code division multiple access (Bi-OCDMA) technique based on spectral amplitude coding for the formation and transmission of optical-polarized and coded signals over wireless optical channels. Compared with conventional Bi-OCDMA schemes, the proposed free-space optics communication system that uses a dual electro-optical modulator design improves the transmission rate. In theory, multiple access interference can be removed by using correlation subtraction schemes. The experiment results revealed that the proposed system can be employed to accurately extract codewords from an M-sequence and subsequently reconstruct the desired original data. Moreover, the proposed architecture can be implemented easily in simple and cost-effective designs and may be beneficial for broadening the use of Bi-OCDMA schemes in wireless optical communications. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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13 pages, 3410 KiB

Open AccessArticle

Polarization Beam Splitter Based on Si₃N₄/SiO₂ Horizontal Slot Waveguides for On-Chip High-Power Applications

by Yuxi Fang, Changjing Bao, Zhonghan Wang, Yange Liu, Lin Zhang, Hao Huang, Yongxiong Ren, Zhongqi Pan and Yang Yue

Sensors 2020, 20(10), 2862; https://doi.org/10.3390/s20102862 - 18 May 2020

Cited by 6 | Viewed by 5163

Abstract

In this paper, we propose an Si₃N₄/SiO₂ horizontal-slot-waveguide-based polarization beam splitter (PBS) with low nonlinearity for on-chip high-power systems. The coupling length ratio between the quasi-TE and quasi-TM modes (L_TE/L_TM) was optimized [...] Read more.

In this paper, we propose an Si₃N₄/SiO₂ horizontal-slot-waveguide-based polarization beam splitter (PBS) with low nonlinearity for on-chip high-power systems. The coupling length ratio between the quasi-TE and quasi-TM modes (L_TE/L_TM) was optimized to 2 for an efficient polarization splitting. For the single-slot design, the coupling length of the PBS was 281.5 μm, while the extinction ratios (ER) of the quasi-TM and quasi-TE modes were 23.9 dB and 20.8 dB, respectively. Compared to PBS based on the Si₃N₄ strip waveguide, the coupling length became 22.6% shorter. The proposed PBSs also had a relatively good fabrication tolerance for an ER of >20 dB. For the multi-slot design, the coupling length of the PBS was 290.3 μm, while the corresponding ER of the two polarizations were 24.0 dB and 21.0 dB, respectively. Furthermore, we investigated the tradeoff between the ER and coupling length for the optimized PBSs with single slot or multiple slots. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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12 pages, 3128 KiB

Open AccessArticle

Accurately Shaping Supercontinuum Spectrum via Cascaded PCF

by Jifang Rong, Hua Yang and Yuzhe Xiao

Sensors 2020, 20(9), 2478; https://doi.org/10.3390/s20092478 - 27 Apr 2020

Cited by 14 | Viewed by 3225

Abstract

Shaping is very necessary in order to obtain a wide and flat supercontinuum (SC). Via numerical simulations, we accurately demonstrated shaping the SC using the fiber cascading method to significantly increase the width as well as the flatness of the spectrum in silica [...] Read more.

Shaping is very necessary in order to obtain a wide and flat supercontinuum (SC). Via numerical simulations, we accurately demonstrated shaping the SC using the fiber cascading method to significantly increase the width as well as the flatness of the spectrum in silica photonic crystal fiber (PCF). The cascaded PCF contains two segments, each of which has dual zero-dispersion frequencies (ZDFs). The spectral range of the SC can be expanded tremendously by tuning the spacing between the two ZDFs of the first segmented cascaded PCF. Increasing the pump power generates more solitons at the red edge, which accelerates solitons trapping and improves the spectral flatness of the blue edge. Furthermore, cascading the second segmented PCF by choosing appropriate fiber parameters ensures the flatness of the red end of SC. Therefore, a cost-effective alternative method for broad and flat supercontinuum generation in the near-infrared range is proposed here, which can be implemented easily in any photonics laboratory, where dual ZDFs PCFs are commonly found. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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Review

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22 pages, 823 KiB

Open AccessReview

Virtual Network Embedding for Multi-Domain Heterogeneous Converged Optical Networks: Issues and Challenges

by Yue Zong, Chuan Feng, Yingying Guan, Yejun Liu and Lei Guo

Sensors 2020, 20(9), 2655; https://doi.org/10.3390/s20092655 - 6 May 2020

Cited by 12 | Viewed by 6017

Abstract

The emerging 5G applications and the connectivity of billions of devices have driven the investigation of multi-domain heterogeneous converged optical networks. To support emerging applications with their diverse quality of service requirements, network slicing has been proposed as a promising technology. Network virtualization [...] Read more.

The emerging 5G applications and the connectivity of billions of devices have driven the investigation of multi-domain heterogeneous converged optical networks. To support emerging applications with their diverse quality of service requirements, network slicing has been proposed as a promising technology. Network virtualization is an enabler for network slicing, where the physical network can be partitioned into different configurable slices in the multi-domain heterogeneous converged optical networks. An efficient resource allocation mechanism for multiple virtual networks in network virtualization is one of the main challenges referred as virtual network embedding (VNE). This paper is a survey on the state-of-the-art works for the VNE problem towards multi-domain heterogeneous converged optical networks, providing the discussion on future research issues and challenges. In this paper, we describe VNE in multi-domain heterogeneous converged optical networks with enabling network orchestration technologies and analyze the literature about VNE algorithms with various network considerations for each network domain. The basic VNE problem with various motivations and performance metrics for general scenarios is discussed. A VNE algorithm taxonomy is presented and discussed by classifying the major VNE algorithms into three categories according to existing literature. We analyze and compare the attributes of algorithms such as node and link embedding methods, objectives, and network architecture, which can give a selection or baseline for future work of VNE. Finally, we explore some broader perspectives in future research issues and challenges on 5G scenario, field trail deployment, and machine learning-based algorithms. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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Other

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10 pages, 2855 KiB

Open AccessLetter

Ultrafast Resolution-Enhanced Digital Optical Frequency Comb-Based BOTDA with Pump Pulse Array Coding

by Yichang Wu, Chengkun Yang, Jingshun Pan, Qi Sui and Dawei Wang

Sensors 2020, 20(22), 6411; https://doi.org/10.3390/s20226411 - 10 Nov 2020

Cited by 8 | Viewed by 2410

Abstract

In this letter, a resolution enhancement and signal-to-noise ratio (SNR) improvement scheme for digital optical frequency comb (DOFC)-based Brillouin optical time-domain analysis (BOTDA) ultrafast distributed sensing employing a pump pulse array is proposed. Based on the properties of the time-invariant linear system and [...] Read more.

In this letter, a resolution enhancement and signal-to-noise ratio (SNR) improvement scheme for digital optical frequency comb (DOFC)-based Brillouin optical time-domain analysis (BOTDA) ultrafast distributed sensing employing a pump pulse array is proposed. Based on the properties of the time-invariant linear system and the cyclic revolution theorem, experimental results indicate that its spatial resolution reaches 10.24 m while the frequency uncertainty is below 2 MHz over a 9.5 km fiber. Moreover, the response time is only 209.6 μs and the temperature measurement error is less than 0.52 °C. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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10 pages, 2798 KiB

Open AccessLetter

Optical-Amplifier-Compatible Long-Distance Secure Key Generation Based on Random Phase Fluctuations for WDM Systems

by Ben Wu and Yue-Kai Huang

Sensors 2020, 20(21), 6296; https://doi.org/10.3390/s20216296 - 5 Nov 2020

Cited by 2 | Viewed by 2252

Abstract

We proposed and experimentally demonstrated a secure key generation and distribution system that is compatible with optical amplifiers and standard wavelength-division multiplexing (WDM) transmission systems. The key is generated from the phase fluctuations induced by environmental instabilities. The key generation system is tested [...] Read more.

We proposed and experimentally demonstrated a secure key generation and distribution system that is compatible with optical amplifiers and standard wavelength-division multiplexing (WDM) transmission systems. The key is generated from the phase fluctuations induced by environmental instabilities. The key generation system is tested in a 240 km bidirectional fiber-pair link with multiple optical amplifiers. To demonstrate the compatibility with WDM systems, 38 WDM channels are transmitted together with the key distribution channel. The secret key is protected against eavesdropping and coherence detection attack by the wide-band property of the signal carrier and the fast-changing rate of the phase fluctuations. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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13 pages, 1373 KiB

Open AccessLetter

MongoDB Database as Storage for GPON Frames

by Martin Holik, Tomas Horvath, Vaclav Oujezsky, Petr Munster, Adrian Tomasov and Sobeslav Valach

Sensors 2020, 20(21), 6208; https://doi.org/10.3390/s20216208 - 30 Oct 2020

Cited by 5 | Viewed by 3176

Abstract

This work is focused on creating an open-source software-based solution for monitoring traffic transmitted through gigabit passive optical network. In this case, the data are captured by the field-programmable gate array (FPGA) card and reassembled using parsing software from a passive optical network [...] Read more.

This work is focused on creating an open-source software-based solution for monitoring traffic transmitted through gigabit passive optical network. In this case, the data are captured by the field-programmable gate array (FPGA) card and reassembled using parsing software from a passive optical network built on the International Telecommunication Unit telecommunication section (ITU-T) G.984 gigabit-capable passive optical network GPON recommendation. Then, the captured frames are converted by suitable software into GPON frames, which will be further processed for analysis. Due to the high transfer rate of GPON recommendations, the work describes the issue of writing to the Mongo database system. In order to achieve the best possible results and minimal loss of transmitted frames, a series of tests were performed. The proposed test scenarios are based on different database writing approaches and are implemented in the Python and C# programming languages. Based on our results, it has been shown that the high processing speed is too high for Python processing. Critical operations must be implemented in the C# programming language. Due to rapid application development, Python can only be used for noncritical time-consuming data processing operations. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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9 pages, 3067 KiB

Open AccessLetter

Numerical Analysis and Recursive Compensation of Position Deviation for a Sub-Millimeter Resolution OFDR

by Yueying Cheng, Mingming Luo, Jianfei Liu and Nannan Luan

Sensors 2020, 20(19), 5540; https://doi.org/10.3390/s20195540 - 27 Sep 2020

Cited by 15 | Viewed by 2930

Abstract

We analyze the source of the position deviation and propose a demodulation recursive compensation algorithm to ensure a sub-millimeter resolution in improved optical frequency domain reflectometry. The position deviation between the geometric path and optical path changes with the temperature or strain, due [...] Read more.

We analyze the source of the position deviation and propose a demodulation recursive compensation algorithm to ensure a sub-millimeter resolution in improved optical frequency domain reflectometry. The position deviation between the geometric path and optical path changes with the temperature or strain, due to the elastic-optic and thermal-optic effects. It accumulates along the fiber and becomes large enough to affect the spectral correlation between the measured and reference spectra at the fiber end. The proposed algorithm compensates for the position deviation of each measuring point and aligns the measured spectra with its reference. The numerical and experimental results both reveal that the signal-to-noise ratio of the correlation is improved doubly and a sub-millimeter spatial resolution becomes available at a 30 m fiber end. The recursive compensation algorithm helps to restrain the correlation degeneration at the fiber end and promises an effective approach to a sub-millimeter resolution in optical frequency domain reflectometry. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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9 pages, 4151 KiB

Open AccessLetter

Fluorinated Polyimide-Film Based Temperature and Humidity Sensor Utilizing Fiber Bragg Grating

by Xiuxiu Xu, Mingming Luo, Jianfei Liu and Nannan Luan

Sensors 2020, 20(19), 5469; https://doi.org/10.3390/s20195469 - 24 Sep 2020

Cited by 12 | Viewed by 3349

Abstract

We propose and demonstrate a temperature and humidity sensor based on a fluorinated polyimide film and fiber Bragg grating. Moisture-induced film expansion or contraction causes an extra strain, which is transferred to the fiber Bragg grating and leads to a humidity-dependent wavelength shift. [...] Read more.

We propose and demonstrate a temperature and humidity sensor based on a fluorinated polyimide film and fiber Bragg grating. Moisture-induced film expansion or contraction causes an extra strain, which is transferred to the fiber Bragg grating and leads to a humidity-dependent wavelength shift. The hydrophobic fluoride doping in the polyimide film helps to restrain its humidity hysteresis and provides a short moisture breathing time less than 2 min. Additionally, another cascaded fiber Bragg grating is used to exclude its thermal crosstalk, with a temperature accuracy of ±0.5 °C. Experimental monitoring over 9000 min revealed a considerable humidity accuracy better than ±3% relative humidity, due to the sensitized separate film-grating structure. The passive and electromagnetic immune sensor proved itself in field tests and could have sensing applications in the electro-sensitive storage of fuel, explosives, and chemicals. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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11 pages, 3736 KiB

Open AccessLetter

Bragg Grating Assisted Sagnac Interferometer in SiO₂-Al₂O₃-La₂O₃ Polarization-Maintaining Fiber for Strain–Temperature Discrimination

by Zhifang Wu, Peili Wu, Maryna Kudinova, Hailiang Zhang, Perry Ping Shum, Xuguang Shao, Georges Humbert, Jean-Louis Auguste, Xuan Quyen Dinh and Jixiong Pu

Sensors 2020, 20(17), 4772; https://doi.org/10.3390/s20174772 - 24 Aug 2020

Cited by 5 | Viewed by 2990

Abstract

Polarization-maintaining fibers (PMFs) have always received great attention in fiber optic communication systems and components which are sensitive to polarization. Moreover, they are widely applied for high-accuracy detection and sensing devices, such as fiber gyroscope, electric/magnetic sensors, multi-parameter sensors, and so on. Here, [...] Read more.

Polarization-maintaining fibers (PMFs) have always received great attention in fiber optic communication systems and components which are sensitive to polarization. Moreover, they are widely applied for high-accuracy detection and sensing devices, such as fiber gyroscope, electric/magnetic sensors, multi-parameter sensors, and so on. Here, we demonstrated the combination of a fiber Bragg grating (FBG) and Sagnac interference in the same section of a new type of PANDA-structure PMF for the simultaneous measurement of axial strain and temperature. This specialty PMF features two stress-applied parts made of lanthanum-aluminum co-doped silicate (SiO₂-Al₂O₃-La₂O₃, SAL) glass, which has a higher thermal expansion coefficient than borosilicate glass used commonly in commercial PMFs. Furthermore, the FBG inscribed in this SAL PMF not only aids the device in discriminating strain and temperature, but also calibrates the phase birefringence of the SAL PMF more precisely thanks to the much narrower bandwidth of grating peaks. By analyzing the variation of wavelength interval between two FBG peaks, the underlying mechanism of the phase birefringence responding to temperature and strain is revealed. It explains exactly the sensing behavior of the SAL PMF based Sagnac interference dip. A numerical simulation on the SAL PMF’s internal stress and consequent modal effective refractive indices was performed to double confirm the calibration of fiber’s phase birefringence. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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10 pages, 971 KiB

Open AccessLetter

Compressed Nonlinear Equalizers for 112-Gbps Optical Interconnects: Efficiency and Stability

by Wenjia Zhang, Ling Ge, Yanci Zhang, Chenyu Liang and Zuyuan He

Sensors 2020, 20(17), 4680; https://doi.org/10.3390/s20174680 - 19 Aug 2020

Cited by 11 | Viewed by 2688

Abstract

Low-complexity nonlinear equalization is critical for reliable high-speed short-reach optical interconnects. In this paper, we compare the complexity, efficiency and stability performance of pruned Volterra series-based equalization (VE) and neural network-based equalization (NNE) for 112 Gbps vertical cavity surface emitting laser (VCSEL) enabled [...] Read more.

Low-complexity nonlinear equalization is critical for reliable high-speed short-reach optical interconnects. In this paper, we compare the complexity, efficiency and stability performance of pruned Volterra series-based equalization (VE) and neural network-based equalization (NNE) for 112 Gbps vertical cavity surface emitting laser (VCSEL) enabled optical interconnects. The design space of nonlinear equalizers and their pruning algorithms are carefully investigated to reveal fundamental reasons of powerful nonlinear compensation capability and restriction factors of efficiency and stability. The experimental results show that NNE has more than one order of magnitude bit error rate (BER) advantage over VE at the same computation complexity and pruned NNE has around 50% lower computation complexity compared to VE at the same BER level. Moreover, VE shows serious performance instability due to its intricate structure when communication channel conditions become tough. Moreover, pruned VE presents more consistent equalization performance within varying bias values than NNE. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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10 pages, 2277 KiB

Open AccessLetter

Surface Plasmon Resonance Sensor Based on Dual-Side Polished Microstructured Optical Fiber with Dual-Core

by Haixia Han, Donglian Hou, Nannan Luan, Zhenxu Bai, Li Song, Jianfei Liu and Yongsheng Hu

Sensors 2020, 20(14), 3911; https://doi.org/10.3390/s20143911 - 14 Jul 2020

Cited by 35 | Viewed by 3574

Abstract

A surface plasmon resonance (SPR) sensor based on a dual-side polished microstructured optical fiber (MOF) with a dual core is proposed for a large analyte refractive index (RI; n_a) detection range. Gold is used as a plasmonic material coated on the [...] Read more.

A surface plasmon resonance (SPR) sensor based on a dual-side polished microstructured optical fiber (MOF) with a dual core is proposed for a large analyte refractive index (RI; n_a) detection range. Gold is used as a plasmonic material coated on the polished surface, and analytes can be directly contacted with the gold film. The special structure not only facilitates the fabrication of the sensor, but also can work in the n_a range of 1.42–1.46 when the background material RI is 1.45, which is beyond the reach of other traditional MOF-SPR sensors. The sensing performance of the sensor was investigated by the wavelength and amplitude interrogation methods. The detailed numerical results showed that the proposed sensor can work effectively in the n_a range of 1.35–1.47 and exhibits higher sensitivity in the n_a range of 1.42–1.43. Full article

(This article belongs to the Special Issue Enabling Technology in Optical Fiber Communications: From Device, System to Networking)

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