Palatal prolapse during nasal expiration in patients with myasthenia gravis.

INTRODUCTION/AIMS: We have encountered patients with myasthenia gravis (MG) who exhibited palatal prolapse (PP) during nasal expiration in the supine position while awake. This may be an overlooked cause of dyspnea in MG patients. This study aimed to examine and describe the characteristics of MG patients with PP. METHODS: We reviewed the medical records of 183 consecutive patients who were diagnosed with MG in our hospital from 2012 to 2021. Thirty-two patients underwent laryngoscopy because of bulbar symptoms. Eight of these patients (25%) exhibited PP on laryngoscopy. Clinical features of these eight patients were retrospectively characterized. RESULTS: Median age of the eight patients with PP was 70 years. Six were men. Median body mass index was 21.6 kg/m2 . All patients exhibited PP in the supine position but not the sitting position. Although no patient had abnormal findings on spirometry nor chest computed tomography, six reported dyspnea or difficulty with nasal expiration only in the supine position. PP improved in all four patients who underwent edrophonium testing. All eight patients eventually improved after immunotherapy. DISCUSSION: PP during nasal expiration may be a cause of dyspnea in MG patients, along with respiratory muscle impairment, lung disease, and vocal cord paralysis. Laryngoscopy in the supine position is required to confirm.

Asymptomatic Dysphagia and Aspiration in Patients with Idiopathic Bronchiectasis.

PURPOSE: Although considered contributors to idiopathic bronchiectasis (IB), neither dysphagia nor silent aspiration have been systematically evaluated in IB patients. We aimed to explore the prevalence of asymptomatic dysphagia and silent aspiration in IB patients and to identify parameters predictive of their presence. METHODS: This prospective cohort study included IB patients from our Pulmonary Institute without prior history of dysphagia and without prior dysphagia workup. Swallowing function was assessed by the Eating Assessment Tool (EAT-10) questionnaire and by the Fiberoptic Endoscopic Evaluation of Swallowing (FEES) test. RESULTS: Forty-seven patients (31 females, mean age 67 ± 16 years) were recruited. An EAT-10 score ≥ 3 (risk for swallowing problems) was present in 21 patients (44.6%). Forty-two patients (89.3%) had at least one abnormal swallowing parameter in the FEES test. Six patients (12.7%) had a penetration aspiration score (PAS) in the FEES of at least 6, indicating aspiration. An EAT-10 score of 3 was found to be the ideal cutoff to predict aspiration in the FEES, with a good level of accuracy (area under the curve = 0.78, 95% CI 0.629-0.932, p = 0.03) and sensitivity of 83%. This cutoff also showed a trend towards a more severe disease using the FACED (forced expiratory volume, age, colonization with pseudomonas, extension of lung involvement, dyspnea) score (p = 0.05). CONCLUSION: Dysphagia is prevalent in IB and may be undiagnosed if not specifically sought. We recommend screening all patients with IB for dysphagia by the EAT-10 questionnaire and referring all those with a score of ≥ 3 to formal swallowing assessment.

Awake fiberoptic intubation of a patient with severe multiple trauma in prone position: a case report.

BACKGROUND: Fiberoptic-guided intubation is considered as "gold standard" of difficult airway management. Management of the airway in prone position in patients with severe trauma presenting with penetrating waist and hip injury poses a major challenge to the anesthesiologist. CASE PRESENTATION: A man presented with severe multiple trauma and hemorrhagic shock as a result of an industrial accident with several deformed steel bars penetrating the left lower waist and hip. It was decided to schedule an exploratory laparotomy following extracting the deformed steel bars. Successful administration of awake fiberoptic nasotracheal intubation, performed in a prone position under airway blocks and appropriate sedation, allowed for the procedure. The exploratory laparotomy revealed damage to multiple organs, which were repaired sequentially during a 7-hour surgical operation. The patient's recovery was uneventful, and he was discharged from the hospital one month after the surgery. CONCLUSIONS: Awake fiberoptic nasotracheal intubation, along with airway blocks and appropriate sedation, can be a viable option in patients with severe multiple trauma in the prone position.

ED50 of ciprofol combined with sufentanil for fiberoptic bronchoscopy of different patient populations with pulmonary tuberculosis.

BACKGROUND: Ciprofol is a promising sedative. This study aims to explore the median effective dose (ED50) of ciprofol in inhibiting responses to fiberoptic bronchoscopy in patients with pulmonary tuberculosis (PTB) of different genders and ages when combined with 0.15 µg/kg sufentanil, and to evaluate its efficacy and safety, providing a reference for the rational use of ciprofol in clinical practice. METHODS: PTB patients who underwent bronchoscopy examination and treatment at The Third People's Hospital of Changzhou between May 2023 and June 2023 were selected and divided into four groups using a stratified random method. All patients received intravenous injection of 0.15 µg/kg sufentanil followed by injection of the test dose of ciprofol according to Dixon's up-and-down method. The initial dose of ciprofol in all four groups was 0.4 mg/kg, with an adjacent ratio of 1:1.1. The next patient received a 10% increase in the dose of ciprofol if the previous patient in the same group experienced positive reactions such as choking cough, frowning, and body movements during the endoscopy. Otherwise, it was judged as a negative reaction, and the next patient received a 10% decrease in the dose of ciprofol. The transition from a positive reaction to a negative reaction was defined as a turning point, and the study of the group was terminated when seven turning points occurred. Hemodynamic parameters, oxygen saturation and adverse reactions were recorded at different time points in all groups. The Probit regression analysis method was used to calculate the ED50 of ciprofol in the four groups and compare between the groups. RESULTS: The ED50 of ciprofol combined with 0.15 µg/kg sufentanil for bronchoscopy in the four groups were 0.465 mg/kg, 0.433 mg/kg, 0.420 mg/kg and 0.396 mg/kg, respectively. CONCLUSION: The ED50 of ciprofol used for fiberoptic bronchoscopy varied among PTB patients of different genders and ages. TRIAL REGISTRATION: The Chinese Clinical Trial Registry, ChiCTR2300071508, Registered on 17 May 2023.

A novel approach to calculate the required volume of air for bronchial blockers in young children.

INTRODUCTION: Bronchial blocker balloons inflated with small volumes of air increase balloon pressure, involving a risk of airway injury especially in young children. However, there are no established guidelines regarding the appropriate volumes of air required to provide safe bronchial occlusion. METHODS: This study aimed to introduce a novel method for calculating the amount of air required for safe bronchial blocker balloon occlusion for one lung anesthesia in young children. We included 79 pediatric patients who underwent video-assisted thoracoscopic surgery at our hospital. Preoperatively, the balloon pressure and corresponding diameter of 5F bronchial blockers inflated with different volumes of air were measured. Intraoperatively, bronchial diameters measured by computerized tomographic scans were matched to the ex vivo measured balloon diameters. The quality of lung isolation, incidence of balloon repositioning, and airway injury were documented. Postoperatively, airway injury was evaluated through fiberoptic bronchoscopy. RESULTS: Balloon pressure and balloon diameter showed linear and nonlinear correlations with volume, respectively. The median lengths of the right and left mainstem bronchi were median (interquartile range) range: 5.3 mm (4.5-6.3) 2.7-8.15 and 21.8 (19.6-23.4) 14-29, respectively. Occluding the left mainstem bronchus required <1 mL of air, with a balloon pressure of 27 cm H2O. The isolation quality was high with no case of mucosal injury or displacement. Occluding the right mainstem bronchus required a median air volume of 1.3 mL, with a median balloon pressure of 44 cm H2O. One patient had poor lung isolation due to a tracheal bronchus and another developed mild and transient airway injury. CONCLUSION: The bronchial blocker cuff should be regarded as a high-pressure balloon. We introduced a new concept for safe bronchial blocker balloon occlusion for one-lung ventilation in small children.

Validation of the European Portuguese Version of the Yale Pharyngeal Severity Rating Scale.

This study aimed to validate the Yale Pharyngeal Residue Severity Rating Scale's European Portuguese version and investigate the impact of rater experience. The scale measures the severity of residue in the vallecula and pyriform sinus. Ninety Fiberoptic Endoscopic Evaluation of Swallowing images were selected after consensus and proposed to 13 raters who were asked to assess the severity of pharyngeal residue (PR) in each image in two moments with an interval of two weeks. The raters were divided by years of experience conducting the Fiberoptic Endoscopic Evaluation of Swallowing and in experience using severity scales for residues. Construct validity, inter-rater, and intra-rater reliability were assessed by kappa statistics. The original English scale was translated into European Portuguese using a forward-backward method for validation. The scale reliability was strong, with an elevated intra-rater internal consistency for vallecula (Cronbach's alpha = 0.982) and pyriform sinus (Cronbach's alpha = 0.922). Inter-rater reliability for raters was equally significant and high for vallecula (0.613 for first assessment and 0.604 for second assessment) and pyriform sinus (0.558 for first assessment and 0.509 for second assessment) or for raters with experience using Yale Pharyngeal Severity Rating Scale (vallecula with 0.832 for first assessment and 0.717 for second assessment and pyriform sinus with 0.856 for first assessment and 0.714 for second assessment).The European Portuguese version of the Yale Pharyngeal Severity Rating Scale is a valid, reliable instrument for scoring the location and severity of pharyngeal residue in the context of fiberoptic endoscopic evaluation of swallowing.

Fiberoptic Endoscopy Evaluation of Swallowing (FEES) Findings Associated with High Pneumonia Risk in a Cohort of Patients at Risk of Dysphagia.

Aspiration detected in the fiberoptic endoscopy evaluation of swallowing (FEES) has been inconsistently associated with pneumonia, with no evidence of the risk of pneumonia from other alterations in swallowing safety detected in FEES. We conducted a dynamic, ambidirectional cohort study involving 148 subjects at risk of dysphagia in a tertiary university hospital. Our aim was to determine the risk of pneumonia attributed to alterations in swallowing safety detected during FEES. We used multivariate negative binomial regression models to adjust for potential confounders. The incidence density rate (IR) of pneumonia in patients with tracheal aspiration of any consistency was 26.6/100 people-years (RR 7.25; 95% CI: 3.50-14.98; P < 0.001). The IR was 19.7/100 people-years (RR 7.85; 95% CI: 3.34-18.47; P < 0.001) in those with laryngeal penetration of any consistency and 18.1/100 people-years (RR 6.24; 95% CI: 2.58-15.09; P < 0.001) in those with pharyngeal residue of any consistency. When adjusted for aspiration, the association of residue and penetration with pneumonia disappeared, suggesting that their risk of pneumonia is dependent on the presence of aspiration and that only aspiration is independently associated with pneumonia. This increased risk of pneumonia was significant in uni- and multivariate negative binomial regression models. We found an independently increased risk of pneumonia among patients with dysphagia and aspiration detected during FEES. Alterations in the oral and pharyngeal phases of swallowing, without aspiration, did not increase the risk of pneumonia.

Pharyngeal Residues Scoring through the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS): Efficacy of Training.

The assessment of pharyngeal residues during fiberoptic endoscopic evaluation of swallowing (FEES) is based on visual-perceptual scales that involve clinical subjectivity. Training might be helpful to increase agreement among clinicians. This paper aims to assess the efficacy of training for the assessment of pharyngeal residue in FEES frames and videos through the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS). Twenty-nine clinicians (Phoniatricians, Otorhinolaryngologists, Speech and Language Pathologists) and 47 students in Speech and Language Pathology participated in this study. Fourteen clinicians were randomly allocated to the training group, whilst the remaining 15 served as a control group; all the students participated in the training. Participants scored 30 pairs of videos and frames using the YPRSRS twice, before and after the training for the training groups and at least two weeks apart for the control group. Construct validity, defined as the agreement between each rater and the experts' scores, and inter-rater reliability were compared among the groups and between the first and the second assessments to verify the efficacy of the training. Construct validity significantly improved at the second assessment in the training group for the pyriform sinuses videos (baseline 0.71 ± 0.04, post-training 0.82 ± 0.05, p = .049) and in the students' group for the valleculae (baseline 0.64 ± 0.02, post-training 0.84 ± 0.02, p < .001) and pyriform sinuses videos (baseline 0.55 ± 0.03, post-training 0.77 ± 0.02, p < .05). No significant differences were found in the inter-rater reliability in any group. In conclusion, the training seems to improve participants' agreement with experts in scoring the YPRSRS in FEES videos.

Pharyngeal Residue Scoring in Fiberoptic Endoscopic Evaluation of Swallowing: Reliability Comparison and Applicability Among Different Scales.

Several scales to assess pharyngeal residue in Fiberoptic Endoscopic Evaluation of Swallowing (FEES) are currently available. The study aimed to compare the reliability and the applicability in real clinical practice among four rating scales: the Pooling Score (P-SCORE), the Boston Residue and Clearance Scale (BRACS), the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS), and the Residue Ordinal Rating Scale (RORS). Twenty-five FEES videos were evaluated four times, once for each scale, by four speech and language pathologists. To test intra-rater reliability, the same raters re-assessed the videos two weeks apart. To test the applicability, raters recorded the time required to complete each assessment and the perceived difficulty/ease on a visual-analog scale (VAS). The intra-rater and the inter-rater reliability were calculated with Cohen's weighted Kappa and the Fleiss weighted Kappa, respectively. Time and perceived difficulty/ease scores were compared. The intra-rater reliability analysis showed almost perfect agreement for YPRSRS (k = 0.91) and RORS (k = 0.83) and substantial agreement for P-SCORE (k = 0.76) and BRACS (k = 0.74). Pairwise comparison showed no significant differences among the scales. The inter-rater reliability for the YPRSRS (k = 0.78) was significantly higher than P-SCORE (k = 0.52, p < 0.001), BRACS (k = 0.56, p < 0.001), and RORS (k = 0.65, p = 0.005). The BRACS required the longest time (p < 0.001) and was perceived as the most difficult scale (p < 0.001). The RORS was perceived as the easiest scale (p < 0.05). In conclusion, the YPRSRS showed the highest reliability, while raters perceived the RORS as the easiest to score. These results will allow clinicians to consciously choose which scale to use in clinical practice.

Fiberoptic endoscopic evaluation of swallowing (FEES) in children with spinal muscular atrophy type 1: feasibility, swallowing safety and efficacy, and dysphagia phenotype.

PURPOSE: Although dysphagia is a common symptom among patients with Spinal Muscular Atrophy Type 1 (SMA1), scant data exist on the application of Fiberoptic Endoscopic Evaluation of Swallowing (FEES) in this population. The aim was to analyze FEES feasibility, swallow safety and efficacy, dysphagia phenotype, and agreement with VideoFluoroscopic Swallow Study (VFSS) in children with symptomatic, medication-treated SMA1 and oral feeding. METHODS: 10 children with SMA1 underwent FEES. Six patients had also a VFSS. Two clinicians independently rated FEES and VFSS videos. Swallowing safety was assessed using the Penetration-Aspiration scale (PAS). Dysphagia phenotypes were defined according to the classification defined by Warnecke et al. Swallowing efficacy was evaluated with the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS) in FEES, whereas pharyngeal residue was rated as present or absent in VFSS. RESULTS: FEES was performed in all children without complications. Four children tolerated bolus trials during FEES, in 4 children swallowing characteristics were inferred based on post-swallow residues, while 2 children refused to eat and only saliva management was assessed. The dysphagia phenotype of predominance of residue in the piriform sinuses was documented in 7/8 children. The PAS score was < 3 in 3 children and > 5 in one child. Swallowing efficacy was impaired in 8/8 children. VFSS showed complete agreement with FEES. CONCLUSIONS: FEES is a feasible examination in children with SMA1. Swallowing safety and efficacy are impaired in nearly all patients with strong agreement between FEES and VFSS. Dysphagia is characterized by the predominance of residue in the piriform sinus.

Recent Progress on Microfluidics Integrated with Fiber-Optic Sensors for On-Site Detection.

This review introduces a micro-integrated device of microfluidics and fiber-optic sensors for on-site detection, which can detect certain or several specific components or their amounts in different samples within a relatively short time. Fiber-optics with micron core diameters can be easily coated and functionalized, thus allowing sensors to be integrated with microfluidics to separate, enrich, and measure samples in a micro-device. Compared to traditional laboratory equipment, this integrated device exhibits natural advantages in size, speed, cost, portability, and operability, making it more suitable for on-site detection. In this review, the various optical detection methods used in this integrated device are introduced, including Raman, ultraviolet-visible, fluorescence, and surface plasmon resonance detections. It also provides a detailed overview of the on-site detection applications of this integrated device for biological analysis, food safety, and environmental monitoring. Lastly, this review addresses the prospects for the future development of microfluidics integrated with fiber-optic sensors.

Efficient Sequential Detection of Two Antibiotics Using a Fiber-Optic Surface Plasmon Resonance Sensor.

Antibiotic residues have become a worldwide public safety issue. It is vital to detect multiple antibiotics simultaneously using sensors. A new and efficient method is proposed for the combined detection of two antibiotics (enrofloxacin (Enro) and ciprofloxacin (Cip)) in milk using surface plasmon resonance (SPR) sensors. Based on the principle of immunosuppression, two antibiotic antigens (for Enro and Cip) were immobilized on an optical fiber surface with conjugates of bovine serum albumin using dopamine (DA) polymerization. Each single antigen was bound to its corresponding antibody to derive standard curves for Enro and Cip. The fiber-optic sensor's sensitivity was 2900 nm/RIU. Detection limits were calculated to be 1.20 ng/mL for Enro and 0.81 ng/mL for Cip. The actual system's recovery rate was obtained by testing Enro and Cip in milk samples; enrofloxacin's and ciprofloxacin's mean recoveries from the milk samples were 96.46-120.46% and 96.74-126.9%, respectively. In addition, several different regeneration solutions were tested to analyze the two target analytes' regeneration ability; NaOH and Gly-HCl solutions were found to have the best regeneration ability.

Direction-Finding Study of a 1.7 mm Diameter Towed Hydrophone Array Based on UWFBG.

This paper investigates a 1.7 mm diameter ultra-weak fiber Bragg grating (UWFBG) hydrophone towed array cable for acoustic direction finding. The mechanism of the underwater acoustic waves received by this integrated-coating sensitizing optical cable is deduced, and it is shown that the amplitude of its response varies with the direction of the sound wave. An anechoic pool experiment is carried out to test the performance of such a hydrophone array. The test array is a selection of six sensing fibers, each of which is coiled into 9 cm diameter fiber ring suspended in the water to receive acoustic signals. An average sensitivity of -141.2 dB re rad/µPa at frequencies from 2.5 kHz to 6.3 kHz was achieved, validating the detection of the azimuth of underwater acoustic waves. The ultra-thin towing cable system, with free structure, high sensitivity, and underwater target-detection capability has demonstrated great potential for future unmanned underwater vehicle (UUV) applications.

Recent Progress in MEMS Fiber-Optic Fabry-Perot Pressure Sensors.

Pressure sensing plays an important role in many industrial fields; conventional electronic pressure sensors struggle to survive in the harsh environment. Recently microelectromechanical systems (MEMS) fiber-optic Fabry-Perot (FP) pressure sensors have attracted great interest. Here we review the basic principles of MEMS fiber-optic FP pressure sensors and then discuss the sensors based on different materials and their industrial applications. We also introduce recent progress, such as two-photon polymerization-based 3D printing technology, and the state-of-the-art in this field, e.g., sapphire-based sensors that work up to 1200 °C. Finally, we discuss the limitations and opportunities for future development.

Detection and Recognition of Voice Commands by a Distributed Acoustic Sensor Based on Phase-Sensitive OTDR in the Smart Home Concept.

In recent years, attention to the realization of a distributed fiber-optic microphone for the detection and recognition of the human voice has increased, whereby the most popular schemes are based on φ-OTDR. Many issues related to the selection of optimal system parameters and the recognition of registered signals, however, are still unresolved. In this research, we conducted theoretical studies of these issues based on the φ-OTDR mathematical model and verified them with experiments. We designed an algorithm for fiber sensor signal processing, applied a testing kit, and designed a method for the quantitative evaluation of our obtained results. We also proposed a new setup model for lab tests of φ-OTDR single coordinate sensors, which allows for the quick variation of their parameters. As a result, it was possible to define requirements for the best quality of speech recognition; estimation using the percentage of recognized words yielded a value of 96.3%, and estimation with Levenshtein distance provided a value of 15.

GA-BP-Based Low-Noise FBG Hydroacoustic Monitoring System with Reference Sensor.

To address the issue of harsh marine background noise impacting the monitoring signal of fiber-optic hydrophones, we propose a low-noise fiber Bragg grating (FBG) hydroacoustic monitoring system with a reference sensor based on genetic algorithm backpropagation (GA-BP). Through theoretical analysis, we deduce the noise suppression steps of the GA-BP algorithm based on the reference sensor and construct train and test sets based on the data from the reference sensor and monitoring sensor at different times, optimizing the GA-BP algorithm to find the best fitting results and thereby obtaining the low-noise monitoring signal. Experimental results from the anechoic tank show that the proposed method can suppress background noise interference on effective signals and that the suppression effect improves as the background noise increases. The sound pressure sensitivity ranges from -173.76 dB to -171.33 dB at frequencies of 8 kHz to 12 kHz, with a response flatness of less than 2.43 dB. The noise suppression effect is obvious under the condition of poor signal-to-noise ratio (SNR), which can reach more than 18.3 dB. The advantages of the proposed algorithm in array signal processing are further demonstrated by the directivity experiment, which proves that the algorithm has a great potential for engineering applications in harsh marine environment.

Distributed Vibration Sensing Based on a Forward Transmission Polarization-Generated Carrier.

For distributed fiber-optic sensors, slowly varying vibration signals down to 5 mHz are difficult to measure due to low signal-to-noise ratios. We propose and demonstrate a forward transmission-based distributed sensing system, combined with a polarization-generated carrier for detection bandwidth reduction, and cross-correlation for vibration positioning. By applying a higher-frequency carrier signal using a fast polarization controller, the initial phase of the known carrier frequency is monitored and analyzed to demodulate the vibration signal. Only the polarization carrier needs to be analyzed, not the arbitrary-frequency signal, which can lead to hardware issues (reduced detection bandwidth and less noise). The difference in arrival time between the two detection ends obtained through cross-correlation can determine the vibration position. Our experimental results demonstrate a sensitivity of 0.63 mrad/µÎµ and a limit of detection (LoD) of 355.6 pε/Hz1/2 at 60 Hz. A lock-in amplifier can be used on the fixed carrier to achieve a minimal LoD. The sensing distance can reach 131.5 km and the positioning accuracy is 725 m (root-mean-square error) while the spatial resolution is 105 m. The tested vibration frequency range is between 0.005 Hz and 160 Hz. A low frequency of 5 mHz for forward transmission-based distributed sensing is highly attractive for seismic monitoring applications.

Optimizing Algorithm for Existing Fiber-Optic Displacement Sensor Performance.

This paper describes the optimal design of a miniature fiber-optic linear displacement sensor. It is characterized by its ability to measure displacements along a millimetric range with sub-micrometric resolution. The sensor consists of a triangular reflective grating and two fiber-optic probes. The measurement principle of the sensor is presented. The design of the sensor's triangular grating has been geometrically optimized by considering the step angle of the grating to enhance the sensor's resolution. The optimization method revealed a global optimum at which the highest resolution is obtained.

Multipoint Energy-Balanced Laser-Ultrasonic Transducer Based on a Thin-Cladding Fiber.

This study proposes a novel multipoint transducer system by utilizing the single-mode-multimode-thin-cladding fiber (SMTC) structure. This structure leverages the disparity in mode field diameter between the multimode fiber (MMF) and thin-cladding fiber (TCF) to generate high-amplitude ultrasonic signals safely and efficiently. The fabricated transducer exhibits signal amplitudes 2-3-fold higher compared to conventional laser-ultrasonic transducers. Simulation analysis investigates the impact of the length of the MMF and the diameter of the TCF on coupling efficiency. The coupling efficiency of individual transducer units can be accurately controlled by adjusting the length of the MMF. A three-point energy-balanced laser-ultrasonic transducer system was achieved, with improved energy conversion efficiencies, and the optimal thickness of candle soot nanoparticles (CSNPs) is experimentally determined. Additionally, we carried out experiments to compare the performance of the proposed SMTC-based transducer system under different material conditions using two different photoacoustic materials: graphite-epoxy resin and candle soot nanoparticle-polydimethylsiloxane (CSNP-PDMS) composite. CSNPs, as a cost-effective and easy-to-prepare composite material, exhibit higher photoacoustic conversion efficiency compared to graphite-epoxy resin. The proposed system demonstrates the potential for applications in non-destructive testing techniques.

Deep Integration of Fiber-Optic Communication and Sensing Systems Using Forward-Transmission Distributed Vibration Sensing and on-off Keying.

The deep integration of communication and sensing technology in fiber-optic systems has been highly sought after in recent years, with the aim of rapid and cost-effective large-scale upgrading of existing communication cables in order to monitor ocean activities. As a proof-of-concept demonstration, a high-degree of compatibility was shown between forward-transmission distributed fiber-optic vibration sensing and an on-off keying (OOK)-based communication system. This type of deep integration allows distributed sensing to utilize the optical fiber communication cable, wavelength channel, optical signal and demodulation receiver. The addition of distributed sensing functionality does not have an impact on the communication performance, as sensing involves no hardware changes and does not occupy any bandwidth; instead, it non-intrusively analyzes inherent vibration-induced noise in the data transmitted. Likewise, the transmission of communication data does not affect the sensing performance. For data transmission, 150 Mb/s was demonstrated with a BER of 2.8 × 10-7 and a QdB of 14.1. For vibration sensing, the forward-transmission method offers distance, time, frequency, intensity and phase-resolved monitoring. The limit of detection (LoD) is 8.3 pε/Hz1/2 at 1 kHz. The single-span sensing distance is 101.3 km (no optical amplification), with a spatial resolution of 0.08 m, and positioning accuracy can be as low as 10.1 m. No data averaging was performed during signal processing. The vibration frequency range tested is 10-1000 Hz.