Optical Fiber Devices Research Articles

Phase-Shifted Fiber Bragg Grating by Selective Pitch Slicing.

This paper presents a new type of phase-shifted Fiber Bragg Grating (FBG): the sliced-FBG (SFBG). The fabrication process involves cutting a standard FBG inside its grating region. As a result, the last grating pitch is shorter than the others. The optical output signal consists of the overlap between the FBG reflection and the reflection at the fiber-cleaved tip. This new fiber optic device has been studied as a vibration sensor, allowing for the characterization of this sensor in the frequency range of 150 Hz to 70 kHz. How the phase shift in the FBG can be controlled by changing the length of the last pitch is also shown. This device can be used as a filter and a sensing element. As a sensing element, we will demonstrate its application as a vibration sensor that can be utilized in various applications, particularly in monitoring mechanical structures.

Real-time optical fibre near-infrared chromatic dispersion analyser using collocated optical fibre gratings

We present what we believe to be a novel optical fibre device for real-time measurements of near-infrared chromatic dispersion of a liquid medium from 1100 nm to 1700 nm. This inline optical fibre chromatic dispersion analyser is based upon collocated fibre long-period gratings written adjacently in the core by femtosecond laser inscription yielding 8 attenuation bands associated with different cladding modes, yielding 8 independent measurements. This fibre device is tested on a series of chemical compounds associated with wines. The results for each compound yielded distinctive chromatic responses. A machine learning pipeline was developed that successfully clustered and classified spectral responses of the different chemicals to illustrate the distinctive responses. The limits of detection for these fibre devices ranged from 1×10−3 to 6×10−5 mol/L for the compounds associated with wines, demonstrating the potential usefulness of an optical fibre chromatic dispersion analyser is capable of monitoring in real-time effective chromatic dispersion that is not offered by any current technology.

Experimental testing of additively manufactured embedded fiber optic smart devices for clean energy applications

Abstract An additively manufactured prototype smart device was created to investigate in-flow temperature distributions using embedded high-definition fiber optic sensors within a component for clean energy systems. The devices were created using Ultrasonic Additive Manufacturing to create a unique embedded pathway within a flow conditioner for the high-definition fiber optic sensors to be placed within. The fibers used allowed for temperature measurements to be taken every 0.65 mm along the fiber. The high-resolution fibers were thermally calibrated enable the 2D reconstruction of the temperature profile in the flow path of the structure. This is due to the temperature-related strain response of the material and strain measurements of the fibers. Hot airflow testing of these devices showed the ability to identify localized temperature differences in the flow. The observed strain response within the smart device had higher strain concentrations in the thicker web regions than in the thinner web regions. These higher strain regions resulted in higher uncertainties for the temperature responses. Further calibration is needed to improve the accuracy of the smart devices, specifically within the inner web structures of a flow straightening component. Further investigations of the devices within flow showed the temperature sensing to be independent of the effects of flow velocity. The devices were able to distinguish temperature differences within single and two-phase flow and showed local sensitivity to the temperature changes with the identification of hot and cold spots. The presented results showed the viability of the smart device for obtaining detailed temperature distributions using common industrial components. Eventually, the goal for these smart devices will be to withstand higher temperature and pressure environments such as those experienced in nuclear, fusion, and concentrated solar energy systems.

(Invited) Development of Fiber-Optic Hydrogen Sensor Using Platinum-Supported Tungsten Trioxide-Silica Composite Film

A fiber-optic hydrogen gas sensor using a platinum-supported tungsten oxide-silica composite film was fabricated. This sensor utilizes the absorption of the evanescent field interaction in the hydrogen sensitive clad which was composed of WO3 and SiO2, coated on a silica core with sol-gel process. As a first step, transmission spectra of sensing film itself were measured. The transmittance of the sensitive film decreased in the range of wavelengths above about 500 nm after exposure to pure hydrogen, and the change in transmittance at 1300 nm was greater than that at 850 nm. Then, fiber optic sensor device was fabricated, and the amount of propagating light was measured. In the case of using the light source with a wavelength of 1300 nm, the sensitivity with respect to the hydrogen response was nearly twice and the response speed was faster, compared with those at 850 nm.

Application of advances in the development and production of optical fiber in the development and design of fiber optic devices.

The dimensions of devices based on optical fiber are limited by the sensitivity of the optical fiber to macrobending, which leads to an increase in optical losses at small bending radii. New types of fibers with low macrobending losses make it possible to significantly tighten the dimensions. However, there may be a risk of fiber failure at bending points during the life of the product due to mechanical fatigue. In the article, based on the use of a static fatigue model of silica glass, a simple expression is obtained to estimate the probability of fiber failure under long-term bending stress depending on the length of the bent section, bend radius and humidity, taking into account the result of a proof-test carried out by the fiber manufacturer. The possibility of increasing the mechanical reliability of silica fiber by applying a hermetical carbon coating is discussed. The use of the obtained expressions in design makes it possible to reduce the dimensions of fiber optic products without the risk of reducing their reliability.

Continuous Positive-Pressure Oxygen Supply Improves Fiberoptic Intubation Efficacy and Safety in Patients With Simulated Cervical Spinal Injury: A Prospective Double-Blind Randomized Controlled Study.

Fiberoptic intubation is an important method for tracheal intubation in patients with cervical spine injury. How to effectively and safely complete fiberoptic intubation while maintaining the stability of the cervical spine is very important. This study compared the efficiency and safety of fiberoptic intubation after anesthesia induction under different types of air pressure in patients with simulated cervical spinal injury. In total, 59 adult patients who underwent fiberoptic intubation with a cervical collar for simulated cervical spinal injury were randomly allocated to continuous positive-pressure oxygen, normal-pressure, or intermittent negative-pressure suction groups. After the induction of anesthesia and adequate 100% oxygenation, which confirmed effective neuromuscular blockade, it was deemed appropriate to begin fiberoptic intubation. In the continuous positive-pressure oxygen group, the fiberoptic device was connected through the negative-pressure suction path with 5 L/min oxygen. In the intermittent negative-pressure suction group, the fiberoptic device was connected to the negative-pressure suction device. In the normal-pressure group, the flexible fiberoptic device was not connected to either the oxygen source or the negative-pressure suction device. The intubation time was recorded as the primary outcome measure. The intubation success rate, number of attempts, minimum SpO2, objective lens contamination rate, and incidence of complications were also compared among the groups. Compared with those in the other groups, the median (range) intubation time in the continuous positive-pressure group was 59 (36-181) seconds, which was significantly shorter than that in the normal-pressure group, 167 (46-181) seconds, and the intermittent negative-pressure suction group, 132.5 (38-181) seconds (P=0.04). The success rate of nasotracheal intubation was significantly greater in the continuous positive-pressure group (94.7%, 18/19) than in the normal-pressure group (50%, 10/20) and intermittent negative-pressure suction group (50%, 10/20) (P=0.004). There was a significant difference among the three groups (P=0.043). The median (range) minimum SpO2 during fiberoptic intubation was 100% (99-100%) in the continuous positive-pressure group, 100% (90-100%) in the normal-pressure group, and 99% (88-100%) in the intermittent negative-pressure suction group (P=0.029). However, no statistically significant difference was detected among the groups with complications. The continuous use of positive-pressure oxygen via the negative-pressure suction pathway can improve the efficiency and safety of fiberoptic intubation in patients with simulated cervical spinal injury after anesthesia induction.

Fiber Optic Devices for Diagnostics and Therapy in Photomedicine

AbstractPhotonic technologies have made enormous impacts on modern medicine, advancing disease diagnostics and treatments as well as health monitoring. A long‐standing challenge in the use of light and its widespread effects in photomedicine is the finite penetration of light in tissues. However, judiciously engineered optical fibers helped overcome this challenge and advance light delivery to deep tissues with spatial precision and desired accessibility. In recent years, the development of photonic technologies including optical biomaterials, fiber functionalization, and biomedical device innovations has greatly expanded the scope of light‐based healthcare. Here, the fundamentals and materials of fiber optics to endow themselves with biocompatibility, flexibility, and diverse functionalities required for long‐term implantation are overviewed. The design strategies of lab‐on‐fiber techniques, operation requirements to construct fiber optic sensors, and their health monitoring applications as wearable and implantable devices are presented. The use of fiber optics in major light‐based therapeutic modalities including optogenetics, photodynamic therapy, photobiomodulation, photochemical cross–linking, and photothermal therapy is illustrated to enhance their effectiveness, specificity, and feasibility. In short, a comprehensive review is provided on the fiber optic techniques and the latest photonic devices, which are envisioned to evolve photomedicine in clinical and point‐of‐care practices.

Carbon Quantum Dots (CQDs)-Diphenyl Carbazone (DPCO) loaded thin film sensors for fluorescent and colorimetric dual mode detection of mercury in various water resources

Mitigation of the environmental pollution has attracted huge attention in recent years owing to the caused health hazards. Mercury ions are one of the toxic heavy metals as pollutants that cause severe damage to health and the environment. Fluorometric and colorimetric-based detection of mercury in water resources is gaining popularity globally due to ease of measurement and the possibility of onsite measurement. We herein report a fluorescent and colorimetric dual-mode Diphenyl carbazone (DPCO) and Carbon quantum dots (CQDs) thin film sensor for specific detection of mercury ions. The thin film sensors were characterized using various techniques like XPS, XRD, TEM, and CLSM. The colorimetric detection is based on the specific binding of DPCO with mercury ions forming a violet-colored complex with simultaneous production of protons. The intensity of color formation was quantified with a smartphone camera and the images using ImageJ software yielding a limit of detection (LOD) of 290 ppb. Fluorometric estimation was performed at an excitation wavelength of 365 nm and an emission wavelength of 505 nm which was possible due to the pH sensitive nature of CQDs in the thin film. Mercury (Hg2+) detection to an extent of 1.8 ppb was made possible in the linear range of 0–100 μM using fluorometric method with a response time of 2 min. Accuracy of estimation of Hg2+ detection was evaluated by spiking different water samples like Tap water, and two river water samples and resulted in the range of 100–103 %. Current investigation shows that DPCO-CQDs loaded thin films coupled with a fiber-optic device and smartphone imaging could be used for accurate dual mode sensing of Hg2+ in real water resource samples.

The thermal diffusion blocking effect of holes enclosing core fiber

We have developed a variety of optical fibers with holes enclosing the core to increase the service life of fiber optic devices under high-temperature and high-pressure environments by blocking the diffusion of dopants in the core with the help of air holes. Simulation results show that the fiber with uniformly distributed holes enclosing the core, the more the hole number, the smaller the core hole distance, and the larger the hole radius, the more significant the blocking effect on thermal diffusion. By comparing the refractive index distribution of three kinds of holes enclosing core fibers and single-mode fibers after prolonged high-temperature heating treatment, the thermal diffusion blocking effect of the holes enclosing core fiber is verified. Long-period fiber gratings fabricated by periodic refractive index modulation of holes enclosing core fibers can realize the measurement of various physical parameters. The thermal diffusion blocking effect of the holes enclosing core fiber enables the long-period fiber grating devices to work for a long time under high-temperature and high-pressure environments, showing the potential for practical applications in various industrial processes.

Optical and electrical properties and applications of two-dimensional carbon-based nanomaterials

As an emerging material, two-dimensional (2D) carbon-based nanomaterials have unique optical and electrical properties due to their unique atomic layer structure. On the one hand, due to their high transmittance, high carrier mobility, controllable Fermi level, and wide spectral light saturation absorption characteristics, they can be applied in new-generation solar cells, organic light-emitting diodes, touch screens, and fiber optic devices. On the other hand, due to their unique nanostructure, they have high specific surface area, low diffusion distance, high conductivity, and ion conductivity. They can serve as substrates and work together with other materials as electrode materials for future fuel cells and lithium-ion batteries and have significant advantages in fields such as sensors. This article mainly summarizes the impact of two-dimensional carbon-based nanomaterials represented by graphene, Mxene, and 2D covalent organic frameworks (COFs) on their optical and electrical properties, and summarizes the latest practical applications and research progress of these nanomaterials in the field of optics and electronics. In addition, a corresponding summary and outlook have been made on the problems that need to be solved in future applications of 2D carbon-based nanomaterials.

141: An innovative scintillating optical fiber device for measuring in-vivo kV-CBCT dose

141: An innovative scintillating optical fiber device for measuring in-vivo kV-CBCT dose

Intrarenal pressure detection during flexible ureteroscopy with fiber optic pressure sensor system in porcine model

To validate the feasibility of a fiber-optic pressure sensor-based pressure measurement device for monitoring intrarenal pressure and to analyze the effects of ureteral acess sheath (UAS) type, surgical location, perfusion flow rate, and measurement location on intrarenal pressure (IRP). The measurement deviations and response times to transient pressure changes were compared between a fiber-optic pressure sensing device and a urodynamic device IRP in an in vitro porcine kidney and in a water tank. Finally, pressure measurements were performed in anesthetized female pigs using fiber-optic pressure sensing device with different UAS, different perfusion flow rates, and different surgical positions at different renal calyces and ureteropelvic junctions (UPJ). According to our operation, the result is fiber optic pressure sensing devices are highly accurate and sensitive. Under the same conditions, IRP varied among different renal calyces and UPJ (P < 0.05). IRP was lowest at 50 ml/min and highest at 150 ml/min (P < 0.05). Surgical position had a significant effect on IRP (P < 0.05). 12/14 Fr UAS had a lower IRP than 11/13 Fr UAS. Therefore fiber optic pressure sensing devices are more advantageous for IRP measurements. In ureteroscopy, the type of ureteral sheath, the surgical position, the perfusion flow rate, and the location of the measurement all affect the intrarenal pressure value.

Advances in laser‐based manufacturing techniques for specialty optical fiber

AbstractAs demand for customized specialty fibers grows, standardized production methods face challenges. This article reviews industry standards and discusses potentially disruptive techniques that enable rapid prototyping and fabrication of optical fiber devices. Furthermore, we showcase laser powder deposition's (LPD) potential for additive manufacturing (AM) of customized glass structures. In the case of, for example, fiber preforms, although the feasible size is smaller than the industry standard, utilizing laser‐based manufacturing techniques for a small batch production presents an attractive avenue for rapid prototyping and expedites material and design optimization. In the realm of AM of glass, LPD offers numerous benefits, including minimal shrinkage, high densification, and the ability to tailor glass composition to achieve desired optical properties. The article reviews the latest achievements and highlights future directions in this technology.

Analysis and prospects of the field of optical fiber materials and devices in China from the perspective of National Natural Science Foundation of China

Analysis and prospects of the field of optical fiber materials and devices in China from the perspective of National Natural Science Foundation of China

Chemical sensor thin film-based carbon quantum dots (CQDs) for the detection of heavy metal count in various water matrices.

Rising pollution of heavy metals is one of the greatest concerns, especially in water resources globally and has led to significant adverse effects to human health. To uplift the status of human health, detection of heavy metals is of key importance. This study establishes the ability of carbon quantum dot (CQD)-based thin films for the detection of total heavy metal counts based on a fluorescence-based mechanism in various water resources using a fiber optic spectrometer (FOS) device. CQDs and CQD thin films were characterized using various techniques, such as X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and confocal laser scanning microscopy (CLSM), and the sensing capability was evaluated for the detection of heavy metals using an optical fiber system. The analytical parameters of the CQD-based thin film were compared with the estimation carried out using a micro plasma-atomic emission spectroscopy (MP-AES) method. The sensing performances of CQD thin films indicate that they are able to detect five heavy metals individually (lead, nickel, manganese, cobalt and chromium) in combination with a response time of 1 minute. The CQD thin films were able to detect heavy metals with a detection limit of 0.006-0.019 ppm for the analyzed heavy metals with a linear range of estimation analyzed as 0-100 μM. The accuracy of the estimation of all five heavy metals when spiked in various real water samples lies in the range of 100-103%. The result of the study clearly indicates that CQD thin films associated with a fiber optic device have the potential to play a role in point-of-care devices for total heavy metal count detection in complex matrices of water.

Non-coincidence detection of fiber optic circulators based on Hertz-level frequency-shifting heterodyne interferometry

The fiber optic circulator in the form of point diffraction is a key component for coupling fiber optical path and spatial optical path in a laser Doppler vibration measurement system. The coupling efficiency and other performance parameters of fiber optic circulator are great significant for improving measurement accuracy and working distance of vibration measurement system. The conventional circulator coincidence detection methods include energy monitoring method and far-field coincidence monitoring method, which cannot be used to quantitatively analyze the fiber mismatch factors. Therefore, the consistency of the circulator coupling efficiency cannot be guaranteed. To solve these problems, a phase detection technology based on Hertz-level frequency-shifting heterodyne interferometry is proposed. The interferometry phase information is used to calculate the relative spatial positions of optical fibers, and this technology performs quantitative detection in the fiber alignment process. The interference wavefront formed by relative spatial positions of optical fibers is simulated and validated experimentally. The curves of coupling efficiency and wavefront PV value versus different kinds of alignment errors are simulated and analyzed. By fitting the interference wavefront with the Zernike polynomials, the correspondence between different kinds of alignment errors and Zernike coefficients is obtained. The value of Z2 (Zernike coefficient) can be used as the basis for judging whether there is transverse displacement in the Y direction. Similarly, Z3 corresponds to the transverse displacement in the X direction, Z4 corresponds to the longitudinal displacement in the Z direction and Z5 corresponds to the optical axis angle. Through this correspondence relationship, the quantitative separation and analysis of fiber mismatch factors are realized. The experimental results show that the accuracy of this method for measuring lateral displacement is better than 1μm. According to the phase diagram obtained from the experiment, Zernike coefficient fitting is performed. The lateral displacement deviation, longitudinal displacement deviation, and angular deviation are calculated by the coefficients of Z2 to Z5. The fiber adjustment mechanism corrects the transverse displacement deviation. It provides a new detection method for realizing fiber alignment and mismatch correction. Compared with the existing detection methods, the phase detection method based on Hertz-level frequency-shifting heterodyne interferometry solves the quantification problem of fiber coincidence adjustment. This method has the advantages of high measurement accuracy, compact detection structure and composition, and low detection cost. This method has great potential applications in the fields of optical fiber and spatial optical device alignment, optical system aberration detection, and planar wavefront detection.

All-Optical Self-Heated Sensing Platform for Water Content Monitoring in Soil

In this contribution, we propose the use of an advanced all-optical self-heated sensing platform for highly sensitive monitoring of the volumetric water content (VWC) in the soil. The sensor is realized by properly integrating, inside a standard metallic needle, a fiber optic heating device based on core offset light coupling method and a Fiber Bragg Grating (FBG) acting as thermal monitor. The performance of the proposed device was validated through a series of measurements in the range [9 - 36] %VWC in the soil temperature range between 5 and 40 °C. Collected results have demonstrated that the presented platform is able to perform highly stable, fast and robust measurements, with time response lower than 10 seconds. The possibility of tuning the value of the injected power according to the application makes the proposed sensing solution extremely flexible and versatile for its exploitation in large areas and/or long-distance.

Optical Reflection Induced by Flexural Acoustic Wave on Fiber Bragg Grating

Flexural acoustic waves can induce optical reflection peaks on one side of the Bragg wavelength in the reflection spectrum of a fiber Bragg grating, thus laying a cornerstone of active acoustic-optic fiber devices. The acoustically-induced refractive index distribution of FBG is deduced. The mechanism of forming acoustically-induced reflection peaks is investigated using mode coupling theory in vector mode presentation. A precise picture is depicted with the selection rules for mode coupling and observation of phase matching, such that the two-step and the three-step processes for acoustically-induced reflection peaks are identified with experimental confirmation. While the three-step coupling theory is discovered, our theoretical framework also refines the former scalar-mode two-step coupling theory. Empowering the theoretical prediction to perfectly match experiment, this work will facilitate the design and application of novel active fiber-optic devices based on acoustic-optic interactions.

Microsurgery of chronic laryngeal diseases using fiber optic lasers. A review

Background. The treatment of chronic diseases of the larynx is an urgent issue. Chronic larynx masses account for up to 5570% of the upper respiratory tract proliferative diseases. The incidence of vocal apparatus disorders is stable due to increased load on the vocal apparatus, neuro-emotional stress, non-compliance with voice hygiene (smoking, alcohol consumption), nasal and pharyngeal inflammatory diseases, sensibilization, and gastrointestinal disorders. Dysphonia, voice timbre changes, and vocal fatigue are presented in 712% of otorhinolaryngologist patients. Delayed treatment of chronic larynx diseases can lead to upper respiratory obstruction, reduced exercise and self-care tolerance, and disablement in people with voice and speech professions.&#x0D; Aim. To address current treatment methods for chronic diseases of the larynx. Modern surgical and non-surgical treatments of chronic larynx diseases aim to restore voice quality and respiratory function. Over the past 50 years, laser-assisted phonosurgery has gained popularity due to the many benefits of biological tissue exposure to electromagnetic energy and low rates of intra- and postoperative complications.&#x0D; Materials and methods. The literature review was performed using electronic medical libraries and professional printed papers. According to local and foreign data, laryngeal laser surgery is highly precise, minimally invasive, associated with no blood loss, and highly effective. Historically, CO2 laser has been used for the longest time in laryngeal surgery. Modern medical technology has recently introduced surgical systems with novel technicalities for clinical use. In such devices, the laser energy is transmitted through a flexible optical fiber instead of a mirror system, as in the CO2 laser, which has made new surgical high-energy systems more affordable for equipping medical institutions. Currently, the following fiber-optic laser systems are most often used to treat chronic diseases of the larynx: potassium-titanyl-phosphate, diode laser, and "blue" laser with a wavelength of 445 nm.&#x0D; Results. The literature review and analysis of surgical treatment outcomes using fiber-optic laser devices in patients with chronic larynx diseases showed high safety and effectiveness of modern treatments, providing fast recovery of voice and respiratory function.&#x0D; Conclusion. The development of laser devices, including domestic ones, with new wavelengths, makes it possible to work in contact mode in an inert gas environment, which opens up new opportunities for phonosurgery.

Application of LiMgPO4 crystal for proton beam quality control in radiotherapy.

The radioluminescence (RL) emitted by LiMgPO4 detector under proton beam irradiation was investigated in real time at the radiotherapy facility in the Institute of Nuclear Physics Polish Academy of Sciences in Krakow. The facility uses protons accelerated by the AIC-144 isochronous cyclotron up to the energy of 60MeV. The measurements of RL were carried out using a remote optical fiber device with a luminophore detector and photomultiplier located at opposite ends of the optical fiber. A thin slice of LiMgPO4 doped with Tm (1.2mol%) crystal was exposed to the proton beam. The tested detector allowed for the measurement of proton beam current, flux fluence and determination of proton beam time structure parameters. The investigation of LiMgPO4 crystal showed its high sensitivity, fast reaction time to irradiation and possibility of application as the detector for control of proton beam parameters.