Optical Fiber Research Articles

Polyaniline-Coated U-Bent Optical Fiber Aptasensor for Detection of Arsenic in Environmental Matrices

Polyaniline-Coated U-Bent Optical Fiber Aptasensor for Detection of Arsenic in Environmental Matrices

Enhancing the Sensitivity of a Temperature and Relative Humidity Sensor Utilizing Fe₂O₃-Coated Tapered Optical Fiber

Enhancing the Sensitivity of a Temperature and Relative Humidity Sensor Utilizing Fe₂O₃-Coated Tapered Optical Fiber

Performance analysis of cyanoacrylate bonded optical fiber 2 × 2 acoustic couplers for sensing applications

In this paper the behavior of a cyanoacrylate (CA) bonded optical fiber acoustic signal coupler will be studied in detail. A stainless-steel mold was used to create a 2×2 CA coupler that transfers guided waves between two optical fibers. Four FBGs placed at each port were used to assess the repeatability, signal behavior, and performance of the coupler produced. Signal propagation through the network was mapped to determine how the initial acoustic signal traveled and subdivided through the fiber network. To examine the repeatability of the signal coupler interaction, the experiments were performed multiple times. Finally, the acoustic energy transferred through the coupler’s paths was calculated to assess the performance of the 2×2 coupler. The coupler successfully and repeatably transferred an acoustic signal from one optical fiber to another; however, the performance associated with the current coupler design was limited by relatively large excess and return losses. Improvements to the CA coupler design are then proposed from the results.

Clinical and Structural Parameters in Autosomal Dominant Optic Atrophy Patients: A Cross-Sectional Study Using Optical Coherence Tomography

Background: Autosomal Dominant Optic Atrophy (ADOA) is a hereditary optic neuropathy characterized by retinal ganglion cell degeneration and optic nerve fiber loss. This study examined the correlation between clinical and structural parameters in patients with ADOA using optical coherence tomography (OCT) and explored potential clinical biomarkers. Methods: A cross-sectional, case–control observational study included 27 patients with ADOA and 27 age- and sex-matched healthy controls. Clinical examinations, OCT imaging, and OCT angiography (OCTA) were performed. Statistical analyses were conducted to establish correlations between clinical and OCT parameters. Results: Patients with ADOA exhibited gradual bilateral vision loss, central scotomas, and optic disc pallor. Structural OCT analysis revealed significant reductions in central macular thickness, macular volume, ganglion cell complex (GCC), and peripapillary retinal nerve fiber layer compared with controls. Correlation analysis demonstrated associations between worsening clinical parameters (best corrected visual acuity, Sloan Letters Low Contrast Chart 25%, Pseudoisochromatic Test) and increased OCT damage (structural and OCTA). GCC emerged, at least at exploratory terms, as the most important clinical biomarker in patients with ADOA given its multiple positive functional associations, while OCTA parameters correlated with visual field defects. Conclusions: Our study revealed significant correlations between clinical and structural parameters in patients with ADOA, highlighting the importance of OCT in assessing disease severity. GCC measurement shows promise as a clinical biomarker, aiding in disease monitoring. OCTA parameters offer potential early biomarkers for vascular changes. These findings contribute to understanding ADOA pathophysiology and may improve patient diagnosis and management. Further research is warranted to validate these findings and explore potential therapeutic interventions.

Numerical study of a tapered fiber magnetic field sensor based on the ENZ mode

This study introduces what we believe to be a novel magnetic field sensor that utilizes a tapered optical fiber coated with indium tin oxide (ITO) and titanium dioxide (TiO2), operating on an epsilon-near-zero (ENZ) mode. The evanescent field around the tapered optical fiber can excite the ENZ mode of the ITO film, and the TiO2 layer can ensure the phase matching between the fiber core mode and the ENZ mode. The sensor, immersed in magnetic fluid, leverages the unique properties of ENZ materials to achieve a high sensitivity and resolution in the near-infrared (NIR) region. Through a simulation, the sensor demonstrated a maximum sensitivity of 6900 nm/RIU and a magnetic field sensitivity of 370 pm/Oe. The findings suggest that ENZ mode-based optic sensing presents a promising alternative to traditional plasmonic sensing methods, offering potential applications in various fields requiring precise magnetic field measurements.

A Conjugate Linearly Polarized Light Wave Along an Optical Fiber with the Berry Phase Model and Its Magnetic Trajectories According to the Conjugate Frame

In this article, we study how a linear polarized wave that is going along an optical fiber works, which is known not only as a curve on a Lie group but also as a rotation of the polarization plane. What we are trying to show in this article is that linear polarized light waves (PLWs) are related to the Berry phase. Moreover, we give magnetic curves created by N traveling in the electromagnetic trajectories and the optical fiber generated by the electric field N of the PLW moving through the optical fiber. With this described method, we present a mathematical model to conveniently generate the relationships between an optical fiber and the optical angular momentum in a three-dimensional Lie group. The conjugate frame we used in this article removes unnecessary bending around the tangent and enables a more dynamic characterization, which can still be applied even when the second derivative of the curve is zero.

Shape measurement by using multicore optical fiber sensor with asymmetric dual cores

Abstract Shape measurement by using multicore optical fiber sensor has attracted more attention in many fields due to the good consistency of the fiber cores. Three symmetrically arranged cores in multicore fiber are usually used for reconstructing shape by calculating the bending vectors, which will not be achieved when one of the cores is damaged or occupied in actual application. A shape measurement method using multicore optical fiber sensor with asymmetric dual cores is proposed in this paper. Based on analyzing the principle of shape reconstruction and the geometric relationship of asymmetric dual cores in multicore fiber sensor, the bending vector is decomposed. The mathematical expressions for bending curvature and orientation of asymmetric dual cores are derived. The two dimensional (2D) and three dimensional (3D) shape reconstruction results both in finite element modelling simulation and shape measurement experiment based on optical frequency domain reflectometry have shown that the proposed method using multicore fiber sensor with asymmetric dual cores is able to achieve shape measurement, and its performance is comparable and even equivalent to the traditional method by using three symmetrically arranged cores. In the experiment, the maximum relative errors of 2D and 3D reconstructed shapes are 2.653% and 5.139%, respectively. The proposed method, which only needs asymmetric dual cores in the multicore optical fiber sensor for shape reconstruction, will be conducive to solve the limitation of multicore optical fiber sensors in shape measurement applications.

NP-doped Optical Fibers for All-Fiber Integrated Optical Sources, Sensors and Actuators with Self-Sensing Capabilities

NP-doped Optical Fibers for All-Fiber Integrated Optical Sources, Sensors and Actuators with Self-Sensing Capabilities

Intrusion event recognition method for distributed fibre optic sensing systems based on Siamese networks

ABSTRACT Due to its high sensitivity and wide measurement range, the distributed optical fibre sensing system has been widely used in long-distance infrastructure monitoring, where it detects vibration signals caused by external events and provides effective early warnings. Given the complexity and diversity of external intrusion events, traditional closed-set classification methods cannot effectively exclude unknown signals. Open-set recognition methods, on the other hand, involve complex model designs, requiring boundary Algorithms and often the inclusion of information related to unknown classes. In this paper, we combine a Siamese network with a residual network to recognise events in the distributed optical fibre sensing system. Through experiments, by comparing the similarity with data in the database, we not only ensure very high accuracy in closed-set classification but also effectively exclude unknown class signals. Experimental results show that our method successfully rejects unknown class data with a 92% success rate, while maintaining closed-set classification accuracy at an average of 99%. Our approach demonstrates excellent performance.

Influence of polymer solution parameters on optical fiber Fabry-Perot polymer cavities

Abstract Optical fiber polymer-based Fabry-Perot sensors are commonly utilized to detect and measure a wide range of physical and chemical properties. By dipping the cleaved end of a single mode fiber into the polymer solution, a cavity is formed at the end facet of the fiber, as the solution effectively bonds to the fiber surface. The cavity serves as a sensing structure for the interaction with the analyte, ultimately determining the sensor’s sensitivity. Maintaining consistent thickness of the FP cavities is of utmost importance for the coating mechanism, as it directly impacts the sensitivity of the FP sensor. The main aim of this study is to assess and establish a technique that can effectively generate a cavity at the end facet of a fiber. A simulation study is conducted to examine the influence of variations in polymer solution characteristics on the cavity fabrication. Our experimental work involved creating polymer cavities on varying the polymer viscosity on the end facet of optical fibers. Furthermore, the suitability of this proposed approach has been assessed on a range of polymers, examining the fluctuations in the free spectral range of the fabricated FP cavities. The findings of this research highlight the possibility of achieving a repeatable coating on the end facet of fiber, irrespective of the polymer used.

Modern concepts on the mechanisms of endovasal laser coagulation in varicose vein disease

Mechanisms of endovasal laser coagulation (EVLC) applied in varicose vein disease are not fully understood.Purpose. To analyze currently applied EVLC mechanisms so as to prevent hemorrhagic complications and paresthesia caused by these mechanisms.Methods. This review analyses modern theories on EVLC mechanisms when applied in varicose vein disease in the lower extremities.Results. Published experimental and clinical trials, including histological ones, have shown that the degree of vein damage during EVLC session depends on many factors, such as wavelength, intensity, and optical fiber speed. Damage to veins during EVLC procedure depends on various factors, such as direct contact of the vein wall with an optical fiber tip, carbonization of blood elements leading to the increased intravenous blood temperature and to the formation of gas bubbles as well as heat convection on the vein wall through the blood.Conclusion. Destruction of the vein wall during EVLC procedure is the result of a synergistic effect of various damaging factors. Currently, 2-μm laser irradiation is being implemented into clinical practice. This technique provides better vein coagulation under less power values which promotes less postoperative complications.

Fast and light-efficient wavefront shaping with a MEMS phase-only light modulator

Over the last two decades, spatial light modulators (SLMs) have revolutionized our ability to shape optical fields. They grant independent dynamic control over thousands of degrees-of-freedom within a single light beam. In this work we test a new type of SLM, known as a phase-only light modulator (PLM), that blends the high efficiency of liquid crystal SLMs with the fast switching rates of binary digital micro-mirror devices (DMDs). A PLM has a 2D mega-pixel array of micro-mirrors. The vertical height of each micro-mirror can be independently adjusted with 4-bit precision. Here we provide a concise tutorial on the operation and calibration of a PLM. We demonstrate arbitrary pattern projection, aberration correction, and control of light transport through complex media. We show high-speed wavefront shaping through a multimode optical fiber – scanning over 2000 points at 1.44 kHz. We make available our custom high-speed PLM control software library developed in C++. As PLMs are based upon micro-electromechanical system (MEMS) technology, they are polarization agnostic, and possess fundamental switching rate limitations equivalent to that of DMDs – with operation at up to 10 kHz anticipated in the near future. We expect PLMs will find high-speed light shaping applications across a range of fields including adaptive optics, microscopy, optogenetics and quantum optics.

Seven-Core Fiber Composite Structures-Based Mach-Zehnder Interferometer for Bending and Temperature Measurement

AbstractIn the paper, an optical fiber sensor based on a seven-core fiber composite structure is presented, which enables dual-parameter sensing of bending and temperature. The proposed structure is fabricated by combining the strongly-coupled seven-core fibers (SC-SCFs) and a weakly-coupled seven-core fiber (WC-SCF). The SC-SCF acts as a beam coupler and enhances the Mach-Zehnder interference, while the WC-SCF serves as the enhanced section of another Mach-Zehnder interference. Therefore, the spectrum response of the fiber structure mentioned above exhibits a superposition effect of two Mach-Zehnder interferometers (MZIs). Among them, two dips corresponding to different MZIs are used to measure bending and temperature. The experimental results show the bending sensitivity and temperature sensitivity of the two MZIs are −4.238 nm/m−1, −2.263 nm/m−1, 0.047 nm/°C, and 0.064 nm/°C, respectively. It proves that our sensor is very sensitive to bending. Through the dual-wavelength matrix method, the bending and temperature can be measured simultaneously. With the benefit of the composite structure, low cost, and ease of fabrication, the proposed sensor can be used in harsh environments.

SURG-48. LASER INTERSTITIAL THERMAL THERAPY REMODELS THE TUMOR IMMUNE LANDSCAPE IN A MOUSE GLIOMA MODEL

Abstract BACKGROUND Laser interstitial thermal therapy (LITT), a minimally invasive surgical technique for tumor ablation, is increasingly being used to treat primary and recurrent glioma. While the primary goal of using LITT has been to destroy tumor tissue, little is known about the impact of LITT on the overall immune response. To investigate changes in the tumor immune landscape, we utilized a mouse model of LITT and applied it to a poorly immunogenic mouse model of glioma. METHODS SB28 glioma cells were implanted in the right frontal lobe of C57BL/6 mice, and on day 7, an optical fiber is inserted into the tumor, paired with a thermocouple for real-time temperature monitoring. A 30W laser was activated in pulses to maintain a peri-lesional temperature of 44C for 150-180 seconds. The tumor and LITT-associated immune response was analyzed by multiparameter flow cytometry, single cell RNA-seq, and multiplex immunofluorescence. RESULTS LITT (versus sham control) triggered an increase in neutrophils in the tumor during the acute phase at day 3 following treatment. Total immune cell numbers increased over time in both sham- and LITT-treated mice, but there was a significant increase at post-LITT day 7 in select adaptive immune cell populations including type 1 conventional dendritic cells, NK cells, and gamma delta T cells. Monocytes/macrophages comprised the majority of the immune infiltrate, and multiplex immunofluorescence revealed these populations localized to the perimeter of the LITT lesion. scRNA-seq also revealed enrichment of a Fabp5- and Gpnmb-expressing macrophage subset following LITT. CONCLUSIONS LITT modifies the tumor immune infiltrate with increases in neutrophils as well as select adaptive cell and macrophage subsets. Future studies will explore adjunct therapies to further augment the immune response in the setting of LITT.

Abraded optical fibre-based dynamic range force sensor for tissue palpation

Tactile information acquired through palpation plays a crucial role in relation to surface characterisation and tissue differentiation - an essential clinical requirement during surgery. In the case of Minimally Invasive Surgery, access is restricted, and tactile feedback available to surgeons is therefore reduced. This paper presents a novel stiffness controllable, dynamic force range sensor that can provide remote haptic feedback. The sensor has an abraded optical fibre integrated into a silicone dome. Forces applied to the dome change the curvature of the optical fibres, resulting in light attenuation. By changing the pressure within the dome and thereby adjusting the sensor’s stiffness, we are able to modify the force measurement range. Results from our experimental study demonstrate that increasing the pressure inside the dome increases the force range whilst decreasing force sensitivity. We show that the maximum force measured by our sensor prototype at 20 mm/min was 5.02 N, 6.70 N and 8.83 N for the applied pressures of 0 psi (0 kPa), 0.5 psi (3.45 kPa) and 1 psi (6.9 kPa), respectively. The sensor has also been tested to estimate the stiffness of 13 phantoms of different elastic moduli. Results show the elastic modulus sensing range of the proposed sensor to be from 8.58 to 165.32 kPa.

Near-infrared double-layer cascaded metasurface for beam shaping

The vast applicability of collimated flat-topped beam shapers, predominantly constructed from traditional lens elements, is met with challenges when the scale is less than wavelength. Metasurfaces have an excellent ability for optical manipulation, which can provide a promising approach to flat optics. Here, a metasurface-based Gaussian beam shaper is designed to combine the transmission phase principle with geometric transformation methods, which can reshape a 1550 nm Gaussian beam into a flat-topped beam with a uniformity of 84.39%. Furthermore, a cascaded metasurface beam shaper design is proposed to address the significant divergence in the flat-topped beam obtained from the single-layer metasurface. Simulation results indicate the output beam exhibits both uniform intensity and phase distributions over a considerable transmission distance, effectively minimizing the divergence of the output beam. This research has potential applications in various fields, such as optical antennas, fiber optics, and other optical systems.

Development of flip-chip technology for the optical drive of superconducting circuits

We discuss the flip-chip mounting process of photodiodes and fiber sleeves on silicon substrates to meet the increasing demand for fabrication of highly integrated and hybrid quantum circuits for operation at cryogenic temperatures. To further increase the yield and success rate of the flip-chip procedure, the size of the gold stud bumps, and flip-chip parameters were optimized. Moreover, to connect optical fibers to the photodiodes in an optimal position, the fiber sleeves were aligned with specially fabricated alignment circles before applying thermocompression with the flip-chip machine. The mounted photodiodes were tested at both room temperature and cryogenic temperature, and we find that mechanical imperfections of the sleeve-ferrule combination limit the overall alignment accuracy. The experimental results show that our flip-chip process is very reliable and promising for various optical and electrical applications and, thus, paves the way for fabrication of hybrid chips, multi-chip modules and chip-on-chip solutions, which are operated at cryogenic temperatures.

EPI proton resonant frequency temperature mapping at 0.5T in the brain: Comparison to single‐echo gradient recalled echo

AbstractPurposeEvaluate the use of both single‐echo gradient recalled echo (SE‐GRE) and EPI approaches to creating temperature maps on a mid‐field head‐only scanner, both in vivo and on a tissue mimicking gel.MethodsThree 2D protocols were investigated (an SE‐GRE, single‐shot EPI, and an averaged single‐shot EPI). The protocols used either a gradient recalled acquisition or an echo planar acquisition, with EPI parameters optimized for the longer at lower field‐strengths. Phantom experiments were conducted to evaluate temperature tracking while cooling, comparing protocol to measurements from an optical fiber thermometer. Studies were performed on a 0.5T head only MR scanner. Temperature stability maps were produced in vivo for the various protocols to evaluate precision.ResultsThe use of an EPI protocol for thermometry improved temperature precision in a temperature control phantom and provided an 18% improvement in temperature measurement precision in vivo. Temperature tracking using a fast (<2 s) update rate EPI thermometry sequence provided a similar precision to the slower SE‐GRE protocol.ConclusionWhile SE‐GRE PRF thermometry shows good performance, EPI methods offer improved tracking precision or update rate, making them a better option for thermometry in the brain at mid‐field.

SURG-18. INNOVATIVE DRUG-DEVICE COMBINATION FOR THE PHOTODYNAMIC TREATMENT OF PRIMARY GLIOBLASTOMA (GBM) PATIENTS

Abstract Despite advances in neurosurgical technology and techniques, the survival rate of GBM patients has remained relatively unchanged. The main treatments for GBM are associated with difficulties resulting from incomplete tumor resection and recurrence. In such situations, Photodynamic Therapy (PDT) is increasingly popular as an advanced therapeutic strategy, characterized by fewer side effects, minimal toxicity, and more controlled treatment. 5-aminolevulinic acid hydrochloride, (5-ALA HCl) has been used for years as a photosensitizing drug for the intraoperative visualization of GBM tumor tissue, enabling a more complete tumor resection. We demonstrated that, after such fluorescence-guided surgery, a laser light of specific 635 nm wavelength can additionally induce specific tumor cell death via the production of reactive oxygen species. This 5-ALA HCl–based PDT provides an antitumor effect within the tumor resection margins where recurrences occur in almost all patients. After performing pilot studies in over 20 patients with primary GBM, leading to positive safety and survival signals, we designed a new drug-device combination for this specific PDT procedure. It consists of Pentalafen ®, 5-ALA HCl administered orally to the patient before surgery, combined to Heliance®, a balloon device, inflated intraoperatively into the resection cavity, and connected to a controller (laser system) via an optical fiber to produce the light that illuminates the resection margins. A dedicated algorithm enables the duration of the illumination to be automatically computed from the tumor volume. This procedure adds an average of 30 minutes to the neurosurgery and can thus be fully integrated into the standard of care for primary GBM. This new drug-device combination is currently evaluated in a US phase 1 trial (NCT05736406) evaluating the feasibility of different light regimen treatments with the aim of delaying GBM recurrence and improving overall survival. If data is confirmed, it could be applicable to other CNS and solid tumors.

Implementasi dan Pengaruh Time Division Multiplexing (TDM) terhadap Kualitas Transmisi Sinyal

Time Division Multiplexing (TDM) is a multiplexing technique that enables the transmission of multiple signals over a single communication channel by allocating separate time slots for each signal stream. This study aims to analyze the working principles of TDM, examples of its implementation, as well as the benefits and drawbacks of TDM in communication networks. The findings show that TDM can enhance data transmission efficiency through flexible bandwidth allocation, minimizing signal interference and thereby improving signal quality. Due to these advantages, TDM is widely used in fiber optic communication systems, such as telephone and internet networks. Additionally, all data processing is conducted within integrated circuits utilizing Plastic Optical Fiber (POF), allowing TDM to be implemented at a low cost.