This PDF file contains the front matter associated with SPIE Proceedings Volume 12835, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

We report a graphene oxide integrated optical biosensor for the detection of breast cancer cell media. The graphene oxide nanosheets-coated long period grating (GO-LPG) serves as an optical transducer where the GO acts as a bridging interface between optical sensor and external medium. The principle of the optical biosensor is based on alerting the optical signal as a change of local refractive index caused by different analyte concentrations. The proposed biosensor has been implemented to detect the breast cancer cell media with ultrahigh sensitivity, opening the path as a bio-nano-photonic platform for biosensing and early diagnosis.

In this talk, the current status and future prospects of health care instruments using mid-infrared light (6 microns or longer) and deep ultraviolet light (shorter than 300 nm), which have not been utilized much in the past for health care applications, are reported. The results of non-invasive blood glucose measurement using mid-infrared quantum cascade laser based on photoacoustic spectroscopy method will be reported. As an example of applications of deep ultraviolet and vacuum ultraviolet spectroscopy using hollow optical fibers as microvolume and long optical path gas cells, the result of highly accurate measurement of acetone in exhaled breath, which is useful for metabolic measurements, will be presented.

The paper discusses all-fiber applicators for the percutaneous laser ablation of tumors, which integrate very dense fiber Bragg grating arrays to add quasi-distributed sensing capabilities. First an assessment of the temperature map distribution reconstruction from the measurements is presented and the impact of some non-idealities is studied; then the developed probes are used to analyze different laser operating conditions, comparing the measurements in ex-vivo porcine livers with modeling expectations.

A new fiber has been developed at Polymicro which has been optimized to significantly improve long term optical transmission stability under high power conditions, such as with Xenon and laser-driven plasma sources. This fiber has been demonstrated to remain stable in the spectral region of 190nm to 1800nm. The fiber is thermostable up to 150°C. In addition, the fiber has demonstrated excellent resistance to X-ray and Gamma radiation.

Dopamine, a vital neurotransmitter in the human body, plays a crucial role in various physiological functions and is closely associated with neurological disorders such as Parkinson's disease. Timely and accurate detection of dopamine levels is essential for effective disease management and personalized healthcare. In this study, we propose an innovative optical fiber-based biosensor utilizing the Localized Surface Plasmon Resonance (LSPR) effect for highly sensitive and selective dopamine detection. The biosensor probe is fabricated using a SMS (Single mode fiber-Multimode fiber-Single mode fiber) optical fiber structure, which is chemically modified to enhance the LSPR effect. Gold nanoparticles are employed to amplify the plasmonic response, enabling improved sensing performance. Experimental analysis is performed using dopamine samples, and the results are obtained using a spectrometer. The developed LSPR biosensor demonstrates great potential for precise and efficient dopamine detection, paving the way for advanced personalized healthcare and improved management of neurological disorders.

Tapered optical fiber sensor (TOFS) devices are attractive as biosensors due to their higher sensitivity, accurate measurement capabilities, and real-time operation. The tapered region allows the evanescent electromagnetic (EM) field to extend outside the fiber to enable the detection of minute changes in the refractive index in close proximity to the tapered region. The sensing is achieved using appropriate functionalized tapered fiber surfaces. In this work, a second generation (2G) automated compact TOFS system developed in our lab is tested, and repeatable and stable signals are obtained proving that this device potentially can serve as a portable bio/chemical sensor in the future. Preliminary simulations, using a FFT based split-step beam propagation method, of optical propagation through a tapered fiber leading to the detected signal as a function of scanning wavelength and its phase shift with cladding refractive index are presented.

We report our progress on the design of a highly sensitive photoacoustic spectroscopy sensor using an extrinsic Fabry- Perot interferometer fiber-optic microphone for detecting parts-per-billion-level trace gas concentrations. A theoretical model is set up to predict the mechanical behavior of the sensor and extended with a mathematical framework for detecting gas concentration from the generated acoustic modes in a photoacoustic gas cell. A detection limit up to 1.55ppb for Nitric oxide is predicted based on the model for a minimum detectable pressure of 2.1μpa√Hz. We also investigated different frequency response of two different gas cells with the finite element method (FEM) using COMSOL for the fiber-optic acoustic sensor.

The paper presents an all-optical system for the detection of bacterial contamination in flowing water that combines the readings from a multi-functional fiber Surface Plasmon Resonance (SPR) sensor with fluorescence measurements. The preliminary application to cases of water contaminated with Escherichia coli is discussed.

Tuberculosis (TB) is the second deadliest infectious disease claiming the lives of 1.6 million individuals annually. One of the significant challenges in controlling the spread of TB is the lack of affordable, user-friendly, and rapid TB diagnostic facilities. Currently, the conventional method for diagnosing TB involves a sputum culture test. Although highly accurate, this approach necessitates specialists, expensive laboratory facilities, and weeks to generate results. A more efficient and non-invasive approach involves targeting TB biomarkers in urine samples. A TB patient's urine contains an additional glycolipid called lipoarabinomannan (LAM) that acts as a TB biomarker. Here, we demonstrate a rapid and portable optical sensor that utilizes a functionalized tapered fiber and phase shift-cavity ringdown spectroscopy (PS-CRDS) to detect LAM in an aqueous solution. We employ motorized stages and a flame to fabricate tapered fibers from single-mode fibers, thereby reducing their diameter from 125 μm to 10-15 μm, enabling them to interact with the surrounding analyte effectively. To specifically target LAM in a solution, we develop a functionalization process that involves a silanization step followed by anchoring an aldehyde-bearing monolayer onto the fiber's surface. The surface aldehyde groups facilitate the covalent attachment of CS-35 LAM antibodies, which only target LAM in a urine sample. The functionalized tapered fiber is the sensing head in the proposed sensing modality. We perform experiments to detect LAM concentrations in aqueous solutions using PS-CRDS. The sensor offers a minimum detection limit of 2 pg/ml and a sensitivity of 2.74 ^o/mgl⁻¹. The proposed sensor is a step toward a rapid, specialist-free, and non-invasive TB diagnostics platform.

In this paper, the building blocks for a smart glass connector platform are presented. The connector is meant to connect optical fibers, which cannot be connected using conventional connector or splicing technology, e.g. optical sensing fibers embedded in composite structures for structural health monitoring purposes. We are setting up a technology platform using aluminosilicate glass substrates as interposer between 2 optical fibers that need to be connected. Using femtosecond laser technology, this interposer can be equipped with basic building blocks such as low-loss intermediate single mode waveguides, couplers and Bragg grating sensors. To this end, femtosecond laser-written waveguides are inscribed in aluminosilicate glass (Xensation® Cover float glass) and the laser parameters are optimized. Waveguides with estimated propagation losses of 0.65 dB/cm are obtained and are subsequently used to make couplers in glass. These couplers can be tuned in coupling ratio between 87:13 and 15:85 by varying the coupling length from 1 to 4.5 mm at a pitch of 17 μm. In addition, fs-laser written Bragg gratings were manufactured, with the goal to add monitoring capabilities to the interposer. These were realized by modulating the fs-laser pulse train and as such a reflectivity up to 5.9% was achieved in the C-band for 23 mm long Bragg gratings. When properly designed, these can be made compatible with standard read out equipment for fiber Bragg gratings (FBGs).

Edible oil adulteration poses a significant threat to public health and erodes consumer trust in the food industry. This study presents an innovative approach to detect edible oil adulteration by leveraging the capabilities of Fiber Bragg Grating (FBG) sensors, known for their speed and accuracy. The FBG based sensors were employed to monitor the refractive index (RI) of edible oils (pure coconut oil), enabling the identification of adulterants introduced during the adulteration process with a lower-quality oils such as paraffin oil. Rigorous experiments were conducted to assess the reduced graphene oxide (rGO) coated FBG sensor’s efficacy in detecting adulteration. The remarkable sensitivity and specificity of the rGO-coated eFBG sensor were demonstrated through its ability to detect and measure even minute changes in RI induced by the presence of adulterants. Utilizing rGO-coated eFBG sensors yielded a sensitivity of 26.62 nm/RIU. Indicating the potential of FBG sensors to improve food safety and quality control regulations, the results exhibit the capability of these sensors to detect paraffin-adulterated coconut oil.

In this manuscript we present the steps required to fabricate, modify, and measure a plasmonic metasurface array for cross-reactive sensing applications. Multiple arrays of gold nanostructures were fabricated using a standard top-down electron-beam lithography process and then enclosed in a microfluidic chamber. Partial-selectivity was then achieved by using different thiol chemistries to modify each array. Finally, measurements of various samples were taken using a custom-built microscope setup.

We report on the development of mid-infrared spectroscopy-based sensors for inline water and wastewater analysis. Midinfrared spectroscopy is a powerful tool for chemical identification and quantification. To overcome the limitations of the technique imposed by rapid extinction of the infrared signal in water, we have developed pre-concentration techniques that achieve beyond four orders of magnitude enhancement of measurement sensitivity, along with enhanced selectivity, for analytes. Applications include monitoring of nutrients and metabolites in bioreactor systems for wastewater treatment and industrial processes (e.g. biofuel production), in-line process control in chemical manufacturing, and rapid on-site screening of contaminants in environmental samples for assessment and remediation of environmental contamination sites.

Pesticides play a crucial role in the modern agricultural system, but growing concerns regarding their toxicity and environmental persistence necessitate the development of innovative detection methodologies to better monitor their impact. Surface-Enhanced Raman Scattering (SERS) has emerged as a promising new tool for sensitive and rapid detection of trace pesticides. This study demonstrates the applicability of ink-jet printed SERS (P-SERS) substrates, fabricated from chromatography paper embedded with gold or silver nanoparticles, for quantitative SERS (qSERS) assessment of different classes of pesticides.

Test samples (malathion, arsenate, benomyl, thiram, and paraquat) were prepared by depositing dilute pesticide solutions onto the P-SERS substrates. The limit of detection for pesticides was improved drastically with P-SERS compared to normal reflective Raman, enabling the detection at concentrations as low as 1 μM. To facilitate quantitative analysis, a robust Raman model was developed to accurately predict pesticide concentrations ranging from 0.0 – 20.0 μM. The model exhibited high coefficients of determination (R2 ~ 0.96) and standard error values (SE ~ 1.3 μM) for both calibration and validation sets, affirming the quantitative potential of qSERS.

Meticulous attention to sample preparation procedures was imperative for ensuring accuracy and reproducibility. A comprehensive Standard Operating Procedure (SOP) that encompasses detailed guidelines for substrate preparation is advocated for qSERS testing; including sample application, drying, and mounting, as well as for Raman instrument operations, involving raster scanning and data collection methods. Strictly adherence to these protocols ensures consistency and reliability in results.

The proposed ink-jet printed SERS approach combined with raster scanning offers a rapid and cost-effective alternative to conventional techniques such as chromatography, mass spectrometry, and electrochemistry. Including sample preparation time, qSERS analysis can be completed in minutes, compared to other analysis methods that can take several hours. Moreover, the streamlined process minimizes consumables and waste generation, underscoring the superiority of SERS over traditional methodologies in terms of efficiency and environmental impact.

Long-Period Fiber Grating (LPFG)-based biosensors operate on the fundamental principle that changes in the surrounding refractive index (SRI) can be translated into measurements of resonance wavelength shifts or variations in transmission loss. Through continued exploration of writing method for LPFGs, various gratings with special structures and novel functions have been designed and developed garnering increasing attention in the realm of novel optic devices. Currently, the fabrication of LPFGs primarily involves altering the effective refractive index of the fiber core using methods such as the mask method and holography, which result in a permanent change in the refractive index of the fiber core. However, this paper explores a method of fabricating dynamic LPFGs based on the principle of acousto-optic effect, whose applications could be more convenient in certain cases. The propagation of ultrasonic waves within the fiber optic induces periodic elastic strain of the fiber, leading to corresponding changes in the fiber’s refractive index over time and space. By modulating the characteristics of the ultrasound, various types of LPFGs can be generated. The feasibility of this method is verified through experiments, and two special gratings, namely dynamic phase-shifted long-period fiber grating and dynamic chirped long-period fiber grating, are fabricated based on the variations in ultrasonic characteristics. This development presents a new technique for addressing fiber optic sensing requirements and opens avenues for future applications such as the detection of immunoglobulin, bacteria, DNA, blood antibody analysis and other targets.

Bioproduction is becoming increasingly important for the pharmaceutical industry. Real-time impurities monitoring during the purification phase could increase productivity and reduce drug cost. Here, we present a silicon photonics platform based on biofunctionalized Mach Zehnder Interferometers for this application. We demonstrate host cell proteins detection in the μg/ml range within 1 min, as well as the possibility to serially monitor up to 8 samples using a single silicon die.

Fiber sensors are commonly used in a variety of applications, detecting signals related to environmental, physiological, optical, chemical, and biological factors. Thermally drawn fibers offer numerous advantages over other commercial products, including enhanced sensitivity, accuracy, improved functionality, and ease of manufacturing. Multimaterial, multifunctional fiber sensors are good candidates for encapsulating essential internal structures within a micro-scale fiber, as opposed to macroscale sensors that require separate electronic components. The compact size of fiber sensors enables seamless integration into existing systems, providing the desired functionality. Here, we present a multimodal, sub-THz fiber antenna that monitors, in real-time, the local deformation of the fiber and the environmental change by a foreign object in fiber proximity. An electromagnetic wave generated by Time Domain Reflectometry (TDR) propagates through the fiber, allowing for the precise determination of spatial changes along the fiber with exceptional resolution and sensitivity. The local change in impedance measures deformation on the fiber, and proximity is detected by a change in the evanescence field formed around the fiber. The fiber antenna works as a waveguide, where the symmetric and antisymmetric modes are analyzed separately to detect local deformation through the antisymmetric mode and environmental changes through the symmetric mode. The fiber sensor's multifunctionality broadens the fiber's application area from biomedical engineering to cyber-physical interfacing. In antisymmetric mode, the Sub-THz fiber antenna can sense local changes in pressure, temperature, pH, and many other physiological parameters. Furthermore, fiber operating in symmetric mode can be used in touch screens, environmental detection for security, cyber-physical interfacing, and human-robot interactions.

Power-over-fiber (PoF) is a novel power transmission technology that uses optical fibers, instead of the traditional copper wires, to deliver electrical power to feed remote sensors or electrical devices. Research on the PoF systems has been receiving extensive attention due to the advantages of fiber optic systems compared to the conventional power supply systems. Optical fibers are less bulky and lightweight, robust to electromagnetic interference (EMI) and electric sparks, resistant to corrosion and to extreme weather. Optical fiber installation is less susceptible to explosive and hazardous environments and presents a minimal security risk. Moreover, a single optical fiber can simultaneously transmit highspeed data and deliver electrical power to remote places. This paper experimentally demonstrates a PoF system using offthe- shelf components to feed microelectronics for low-power applications. The optical system consists of a 1550nm Pigtailed Laser Diode, an InGaAs photodetector for the optical to electrical conversion, and both Single-Mode (SM) and Multi-Mode (MM) optical fibers are tested. Experimental results show that data signal and power signal can be successfully transmitted simultaneously using an optical communication link. Analysis of the electrical-to-optical (E/O) conversion efficiency of the laser source, optical-to-optical (O/O) efficiency of the optical fibers, and optical-to-electrical (O/E) conversion efficiency of the receiver are also presented. Moreover, the System Energy Efficiency (SEE) is studied, and the effects of signal data-rate on the SEE are investigated.

The existing optical fiber terrestrial network can be leveraged to serve as a wide distributed network of sensors, especially to detect mechanical stresses as the optical signal polarization is significantly influenced by external disturbances. Exploiting this trend, paves the way for employing the optical fiber network in environmental sensing, like detecting earthquakes or tracking anthropic activities. The purpose is to examine the changes in the state of light polarization caused by birefringence induced by seismic events. Consequently, we have developed a Python-based Waveplate Model to track state of light polarization changes in buried optical fiber cables. This model integrates real ground motion data from a 4.9 magnitude earthquake that occurred southwest Marradi city in Italy, and converts it into strain values along the fiber cable. To further investigate the effects of this particular seismic activity, we propose a centralized smart grid fiber network approach based on a neural network model with an attention mechanism for earthquake early warnings. Along with the aforementioned Waveplate Model, numerous sets of polarization evolution were produced on two distinct sensing points with different distances from the epicenter in two different cities, enabling earthquake early detection upon P-wave arrivals that precede the earthquake’s destructive surface waves and allowing for a swift initiation of emergency plans including early warning alerts and earthquake countermeasures.

This paper introduces a double-parameter distributed fiber sensing system that utilizes stimulated Brillouin scattering in a specialized fiber, distinguished by two gain peaks in its scattering spectrum with nearly identical intensity levels. Employing this specialty fiber in a Brillouin optical time domain analysis system, we conduct a comprehensive analysis highlighting their efficacy in the simultaneous measurement of strain and temperature. These fibers are characterized by a significant temperature coefficient disparity (~0.2 MHz/°C) between the two peaks, and similar large peak gain amplitudes resulting minimal Brillouin frequency shift uncertainties, thereby substantially reducing strain and temperature measurement errors. We evaluated strain and temperature coefficients of 47 kHz/με, 1.15 MHz/°C for the first peak, and 51 kHz/με, 1.37 MHz/°C for the second one, which were then applied in the simultaneous measurement of strain and temperature under various conditions, including an applied strain of 1220 με at temperatures of 62°C and 72°C. The results indicate a significant enhancement in measurement accuracy, reducing errors to ~17 με and ~ 0.9°C in terms of strain and temperature respectively. Additionally, strain and temperature errors due to the impact of the variance of Brillouin frequency shift uncertainty between two peaks are explored. This study underscores the potential of the proposed double- Brillouin peak fiber in critical applications such as long-distance natural gas pipeline monitoring, where precise and distinct measurements of strain and temperature are paramount.

Brillouin scattering in optical fibers is widely harnessed for various sensing applications, particularly strain and temperature monitoring. Fiber design/engineering is crucial for optimizing the potential of Brillouin scattering in specialty optical fibers. In this work, we numerically investigate the design recommendations involved in optimizing ring core fibers (RCFs) for discriminate strain and temperature sensing, and additionally, we explored the key design guidelines for achieving high sensitivity in strain and temperature measurements. Our investigation showed that an RCF with a large ring layer, high refractive index contrast, and multiple ring layers portrays enhanced sensitivities to strain and temperature variations.

Cellulose, as a fully renewable, biodegradable, and biocompatible material, creates new possibilities for optical fiber (OF) sensor applications. Cellulose OFs are highly hygroscopic, exhibiting rapid wetting and drying properties with water and moisture, easily functionalized, and can be either made water-resistant or water-soluble. These fibers are not aimed towards replacing the existing glass or polymer OFs in telecommunication or in current sensing applications, rather cellulose OF sensors can open new application areas where the reactive materials are required. For example, compared to glass or polymer OFs, cellulose OFs are porous and allow liquid transport in and out of the fiber. Moreover, the cellulose waveguide material itself can be chemically functionalized. Such cellulose OFs fit well with human health monitoring where the new possibilities that cellulose offers can be utilized. Here we demonstrate a face mask that contains regenerated cellulose (RC) OF with a 1.8 dB/cm attenuation constant for respiratory rate monitoring. RC is a class of man-made cellulose materials that includes commonly materials like rayon textiles and cellophane films. The cellulose fiber inside the face mask rapidly absorbs moist and dries between each breath, which causes a periodic change in optical power transmitted through the fiber. A face mask does not prevent fast drying of the fiber. Such RC fiber fits well to respiratory rate monitoring because it exhibits good mechanical performance in both dry and wet states. Cellulose OF length was about 5 cm long with a loop-type sensor structure. Measured respiratory rates varied between 16-54 breaths per minute.

Carbon-coated optical glass fibers were designed to reduce the hydrogen-induced light attenuation (hydrogen darkening) in harsh environments. The carbon layer reduces the hydrogen permeability, but makes the post-treatment for direct point-by-point inscription of fiber Bragg gratings (FBG) more challenging. Moreover, the laser pulse treatment can greatly affect the tensile strength of the fiber. In this paper, we present direct point-by- point inscription of FBG through carbon-coated fiber layers with femtosecond laser pulses with a center wavelength of 400 nm, achieved via second harmonic generation of Ti:sapphire laser pulses. An array of four FBGs are successfully inscribed in a single-mode fiber. A direct comparison between the 400 nm and 800 nm inscribed FBGs in the carbon fibers is presented. The polarization dependence was examined of FBGs written with both laser processing wavelengths, as well as the mechanical stability of the processed fibers via tensile tests.

Photoplethysmography (PPG) is a non-invasive optical technique used to extract physiological information by means of light interaction with the skin. PPG is widely used in pulse oximeters, and the evolution of wearable technologies is further enlarging its applications. A great variety of influencing factors impact the PPG waveform, making the correct feature extraction difficult and, therefore, limiting the accuracy of many PPG applications. The device hardware and software are among these influencing factors. This study evaluates the impact on the PPG signal quality of the LED viewing angle (luminous aperture) and the protective glass material, thickness, and anti-reflective coating, both important building blocks of a PPG sensor. Results suggest that the larger the viewing angle, the smaller the detected signal amplitude. The protective glass properties on the contrary does not seem to impact the detected signal amplitudes.