Recent advancements in the spatiotemporal engineering of electromagnetic wavefronts have redefined contemporary beam-shaping paradigms, solidifying their role as foundational elements in emergent photonic architectures and precipitating breakthroughs in nanoscale optical physics, hypersensitive metrology, computational imaging, optical sensing, and terabit-scale optical communications. Building upon this technological inflection point, the present investigation delineates a meticulously architected fiber-optic refractometric platform predicated on Airy-vortex beam excitation as distinguished by its intrinsic orbital angular momentum and transversely self-accelerating intensity profile. The principal novelty of the proposed sensing scheme resides in harnessing an Airy-vortex beam, whose unique spatial topology affords highly efficient and selective excitation of higher-order modes within a decladded multimode fiber, thereby augmenting evanescent-field confinement at the fiber-medium boundary. Furthermore, our study was supported by full-vector Beam propagation method (BPM) simulations in OptiBPM (v13.1.3), enabling detailed examination of Airy-vortex beam dynamics across the sensor geometry. The comprehensive beam propagation analysis establishes a peak sensitivity of 2808.49 dB/RIU with the refractive index resolution as fine as 3.56 × 10⁻⁶ RIU, surpassing the Gaussian-mode analogues by a conspicuous margin. Thus, this unique blend of diffraction resilience and structured phase topology inherent to the Airy-vortex beam renders this architecture a compelling platform for high-resolution, real-time refractometric sensing across various chemical, environmental, and biomedical regimes.

Structured-light-based optical sensing has emerged as an effective approach for developing sensitive platforms in cancer-related detection. This work presents a fiber-optic biosensor using an Airy-Vortex beam (AVB) to improve the identification of cancer-related biomarkers. The sensor employs a multimode optical fiber with a decladded core region, thereby increasing evanescent-field interaction with the external environment and boosting light-matter interaction. The sensing mechanism relies on multimode interference (MMI), where variations in transmitted optical power correspond to variations in the analyte's refractive index. Numerical simulations conducted using OptiBPM (version 13.1.3) at 1550 nm demonstrate a response of 888.7 dB/RIU, representing a 3.27-fold enhancement over conventional multimode fiber sensors.The AVB-based sensor differentiates HeLa, Jurkat, MCF7, and PC12 cell lines, indicating its capability to resolve cancer-associated cellular variations. The proposed sensor architecture is suitable for real-time optical biosensing and related biomedical diagnostic applications.

Early detection of oral cancer is crucial for improving patient survival, yet conventional diagnostic techniques remain slow and heavily dependent on chemical reagents. To overcome these limitations, this work proposes a high-sensitivity fiber-optic biosensor illuminated by an Airy-Bessel beam for reliable identification of oral cancerous cells. The sensor is constructed using a cladding-removed multimode fiber, allowing the surrounding analyte to act as the cladding region. This design increases the overlap between the guided light and the analyte, thereby strengthening the evanescent-wave interaction. The use of an Airy-Bessel beam further enhances sensing performance by combining the self-bending characteristics of Airy beams with the non-diffracting nature of Bessel beams, resulting in improved field confinement and coupling efficiency. The sensing mechanism operates on multimodal interference (MMI), where changes in transmitted power reflect the refractive index (RI) contrast between INOK normal cells and YD-10B oral cancer cells. The propagation behavior and sensing response were analyzed using the Beam Propagation Method (BPM) in OptiBPM (v13.1.3). Our Simulations confirm that a 25 cm sensing length achieves a sensitivity of 322.45 dB/RIU, providing a 3.29 -fold improvement compared to Gaussian-beam excitation. With its compact structure, low cost, and fabrication-friendly design, the proposed sensor shows strong potential for early oral cancer detection and broader biomedical sensing applications.

Deliberate contamination of milk with inexpensive or unsafe additives has emerged as a pressing food safety challenge, reducing its nutritional integrity and posing notable risks to consumer health. This work presents a high-performance optical sensing approach employing an Airy-vortex (AV) beam launched into a decladded multimode fiber. This sensing mechanism is based on monitoring the transmission loss variations resulting from evanescent field absorption when the exposed fiber segment is immersed in milk samples adulterated with formaldehyde and hydrogen peroxide. Adulteration levels ranging from 0 % to 14.28 %, corresponding to refractive index(RI) values between 1.34550 and 1.34966, were analyzed to evaluate the sensor's response. Further, the beam propagation characteristics and the sensing behavior were simulated using the OptiBPM (13.1.3) software, which validated the enhanced light-matter interaction achieved through AV excitation. For a sensing length of 6 cm, the proposed configuration achieved sensitivities of 0.1209 dB / % for formaldehyde and 0.1055 dB / % for hydrogen peroxide, offering a notable improvement compared to Gaussianbeam excitation. Thus, the results confirm that Airy-vortex structured light enables a compact, fabrication-friendly, and highly responsive platform for the detection of milk adulteration.

Kidney abnormalities, including cysts, tumors, and stones, affect millions worldwide and present substantial health challenges. Accurate detection and classification of these issues are essential but remain a difficult task. Computed Tomography (CT) scans, a specialized x-ray imaging technology, play a vital role in diagnosing these abnormalities. Recently, machine learning algorithms have become more prominent in these types of tasks; however, conventional machine learning techniques often struggle with data pre-processing, computational efficiency, and disease localization. To address these challenges, we have proposed an enhanced architecture of the YOLOv5 model. In this work, we primarily focused on designing a novel C3SE network method, which integrates Squeeze-and-Excitation (SE) modules with C3 (3Conv) modules within the YOLOv5, significantly improving the network’s ability to detect and classify kidney disorders. Additionally, to improve adaptive optimization of feature aggregation and enhanced detection accuracy, we have employed the BiFPN. Moreover, we incorporate the SE attention mechanism to enhance multi-scale feature extraction, effectively reducing the impact of undesired input features. To validate the performance of the proposed model compared to prior approaches, we evaluated its accuracy, mean average precision (mAP@0.5), precision, F1 score, and recall, achieving 97.5%, 96.8%, 94.1%, 97%, and 96%, respectively. To ensure model interpretability and diagnostic trust, we employed Grad-CAM based explainability, visually confirming that the model accurately localizes pathological features. This promotes transparency in AI-assisted diagnosis, crucial for clinical deployment.

Contemporary advances in the spatial-temporal modulation of electromagnetic wavefields have fundamentally reshaped optical beam-shaping paradigms, positioning structured light as a pivotal enabler of next-generation photonic architectures and catalysing transformative developments in nanoscale optics, ultra-sensitive sensing, computational imaging, and high-bandwidth optical communications. Within this evolving landscape, structured-light engineering has unlocked unprecedented control over modal excitation and propagation dynamics in fiber-optic platforms. Nevertheless, despite these advances, most fiber-optic sensing schemes still rely on conventional Gaussian-beam illumination, which is inherently limited in its capacity to preferentially couple energy into higher-order guided modes, resulting in reduced evanescent-field extension and weaker interaction with the surrounding medium. Motivated by this fundamental shortcoming, the present work unveils what we believe to be a novel waveguide-based refractive index sensing system by launching a Laguerre higher-order cosh-Gaussian beam (LHOChGB), whose non-trivial spatial structure enables preferential coupling of higher-order guided modes within a uncladded multimode fiber, thereby enhancing the evanescent field localization and strengthening the guided-mode interaction with the external medium. Furthermore, our study was corroborated by using the beam propagation simulations based on the finite-difference method in OptiBPM to characterize the propagation dynamics of the LHOChGB within the sensor structure. Such rigorous analysis unequivocally demonstrates an impressive peak absolute sensitivity of 33.72 dB/RIU, representing an approximate 10.6-fold enhancement over the conventional Gaussian-excited sensor, which typically yields a sensitivity of 3.18 dB/RIU. Therefore, this incipient genre of structured optical field propels innovative trajectories in the field of optical sensing and exhibits substantial potential for multifaceted physico-chemical and biosensing applications.

The emergence of structured light as a controllable photonic entity has transformed the manipulation of electromagnetic fields, facilitating advanced light-matter interactions that critically enhance the operational efficiency of diverse fiber-optic sensors. Within this emergent framework, the Airy-Bessel beam, characterized by its non-diffracting propagation and self-healing dynamics, stands as a paradigmatically superior candidate for fiber-based refractive-index measurements. In this investigation, we employed the Airy-Bessel excitation within a decladded multimode fiber to transcend the inherent constraints of conventional Gaussian illumination, whose efficacy is typically curtailed by shallow evanescent-field penetration and diminished mode-medium interaction. By tailoring the excitation conditions, higher-order guided modes are efficiently stimulated, thereby amplifying the evanescent-wave contribution and enabling a superior refractive index sensitivity. The proposed sensor architecture was validated using full-vector beam propagation method (BPM) numerical modeling performed in OptiBPM (v13.1.3, Optiwave Inc.), allowing a comprehensive analysis of Airy-Bessel beam evolution within the sensing structure. The sensor demonstrates absolute sensitivities of 1502.96 dB/RIU and 1878.72 dB/RIU for sensing lengths of 20 cm and 25 cm, respectively, with corresponding detection resolutions of 6.65 × 10−6 RIU and 5.32 × 10−6 RIU. These results affirm a notable advancement over Gaussian beam configurations and highlight that structured-beam excitation enables scalable sensing without the need for geometric alterations such as tapering, side-polishing, U-bending, surface-functionalized designs, etc. Therefore, the proposed sensing method furnishes a potent pathway for futuristic fiber-optic sensing across chemical, biomedical, and environmental domains where ultralow refractive index detection is imperative.

The emergence of structured optical waveforms as precisely engineered photonic frameworks has remarkably propelled the mastery of electromagnetic field distributions, thereby fortifying the light-matter interaction essential for high-performance fiber-optic sensing. In this work, a Tricomi-Gauss beam, characterized by its propagation-invariant behavior, is employed as the excitation source within a decladded multimode fiber to overcome the inherent limitations of conventional Gaussian illumination, which is typically constrained by limited evanescent-field penetration and weaker modal-medium interaction. The key novelty lies in leveraging a Tricomi-Gauss beam to enable selective higher-order mode excitation in a decladded multimode fiber without requiring any structural modification to the waveguide dimensions, thereby augmenting the modal-field interaction with the sensing medium, which leads to intensified evanescent-field strength and enhanced sensitivity to refractive-index variations. This novel sensing configuration is rigorously analyzed using a beam propagation method implemented in OptiBPM, with particular emphasis on modal evolution across the sensing region. Our proposed sensor manifests an exceptional peak absolute sensitivity of 3352.10 dB/RIU, accompanied by a notably refined detection resolution of 2.98×10−6RIU. Therefore, these observations demonstrate the pronounced superiority of the proposed sensor over the Gaussian-based excitation methodology and affirm that structured beam engineering enables coherent, systematic sensitivity amplification without structural intervention in the fiber, making it suitable for next-generation high-performance refractometric sensing applications.

This paper presents a fully integrated solar energy harvesting system and power management unit (SEHS-PMU) for ultra-low-power Internet of Things (IoT) applications. The proposed system is implemented in 45 nm CMOS technology and employs a reconfigurable charge pump (RCP) architecture to achieve efficient energy conversion without using bulky inductors. A maximum power point tracking (MPPT) algorithm enables optimal energy extraction from the solar cell under varying illumination conditions. In addition, capacitor value modulation (CVM) is used for impedance matching, supporting compact monolithic integration. The proposed RCP-based DC–DC converter achieves a peak power conversion efficiency of 95%. Furthermore, on-chip low-dropout regulators (LDOs) generate regulated output voltages of 2.8 V, 1.3 V, and 0.7 V to support different subsystems of IoT, smart city, and IoMT sensor nodes. The proposed SEHS-PMU provides a compact, energy-efficient power management solution that enables sustainable operation of next-generation self-powered IoT devices.

This work introduces a novel approach for enhancing the detection capability of localized surface plasmon resonance (LSPR) optical fiber sensors through the application of a zeroth-order Bessel-Gauss beam in a tapered multimode fiber setup. Traditional LSPR sensors using Gaussian beams in linear fiber geometries often face limitations in achieving strong light-matter coupling. To address this, the Bessel-Gauss beam's non-diffracting nature and extended depth of focus are leveraged to improve plasmonic excitation on metallic nanoparticle layers. Various structural parameters, including the fiber core dimension, taper geometry, and ambient refractive index (RI) are systematically explored. Simulation outcomes indicate that decreasing the core size and increasing the tapering ratio improve confinement of the evanescent field, resulting in heightened RI sensitivity. Furthermore, the observed spectral shifts with changing environmental RI confirm the sensor's responsiveness. These findings underscore the benefits of integrating beam shaping techniques with tapered fiber designs to develop highly sensitive LSPR sensors suitable for environmental sensing, medical diagnostics, and biochemical applications.

Milk has a high nutritional value since it includes a range of nutrients required for the human body's regular growth and maintenance. Consumption of milk has increased dramatically in recent decades and it currently makes up a major chunk of the worldwide diet for a huge percentage of the people. Because of such growing demand, some deceitful producers are engaging in milk adulteration and this misconduct has become a prevalent concern, which lacks strong surveillance by food safety officials. Milk is frequently cheated (adulterated) for financial advantage and some common adulterants are formaldehyde, hydrogen peroxide, urea, water etc. The food sector is concerned about the speedy detection of such adulterants as they reduce the nutritious content of milk, putting customer's health at risk. So, the purpose of this research is to come up with a new design of a very sensitive evanescent wave-based optical sensor to detect various milk adulterants such as formaldehyde and hydrogen peroxide. The sensing structure here is a decladded multimode fiber with an Airy beam shining on it. The detection process is based on the change in transmission loss when a decladded fiber comes into touch with adulterated milk sample. To anticipate accurate sensing, the amounts of adulterants in milk ranged from 0% to 14.28%, with refractive indices varying from 1.34550 to 1.34966 were considered. Moreover, an Eigenmode expansion (EME) study in Lumerical Mode solver has been exploited to corroborate the sensing property of the device, which is in agreement with our theoretical analysis. By considering the sensor length as5 cm, the proposed sensor responded with an admirable sensitivity of 0.05 dB/% (for formaldehyde detection) and 0.04 dB/% (for hydrogen peroxide detection), revealing a 16.66-fold and 20-fold higher sensitivity over the Gaussian-beam shined sensor. The results reveal that there is remarkable linearity between the adulteration level and transmission loss. Thus, the aforementioned principle provides a highly sensitive and simple-to-fabricate approach for detecting various milk adulterations, which might help to tackle severe problems in the food sector.

Oral cancer is a major worldwide health concern that disproportionately affects both men and women in all parts of the globe. The high death rate in underdeveloped nations is primarily attributable to a lack of suitable medical infrastructure and resources to enable a structured screening and diagnosis process. Therefore, early detection of oral cancer is crucial for a patient's survival. Unfortunately, existing screening procedures for oral premalignant and malignant lesions overlook a large percentage of individuals. Moreover, the current clinical approaches for detecting the oral cancerous cell are time-consuming and require the use of labeled reagents for laboratory analysis. Considering such context, this article describes a high-sensitive fiber-optic biosensor that detects oral malignant cells using a Vortex beam. Here, a claddingless multimode fiber with a Vortex beam shining on it serves as the sensing structure. It is based on the conception of multimodal interference in which the output optical power from the fiber end fluctuates due to the presence of various oral cancerous cell (YD-10B cell group) at the cladding medium. To anticipate accurate sensing, theoretical analysis was carried out for two kinds of living cells: the normal INOK cell and the malignant YD-10B cell. An Eigenmode expansion (EME) analysis in Lumerical Mode solver has been properly manipulated to simulate the sensing property of the device. By optimizing the sensing length for 5 cm, the suggested sensor responded with an admirable sensitivity of 644.9 dB/RIU, which unveils a 4.4-fold enhanced sensitivity than the existing Gaussian-beam shined sensor. Thus, the said sensing principle provides a label-free, easy-to-fabricate and straightforward technique to detect oral cancerous cells, which might be beneficial as a biosensor in biophotonics.

A lot of water bodies around the world are suffering from severe contamination which poses problems to the marine life as well as to all those living around them. Such problem could be brought down by just monitoring the water body. So, this paper mainly aims on the development of a microcontroller-based water quality monitoring system by measuring various decisive parameters like pH and temperature. The performance of the device has been corroborated by considering various water samples like mixture of lemon juice and water, soda, bottled water, tap water and mixture of laundry detergent. The developed system is being observed to efficiently measure pH and temperature with a maximum relative error of 3.75% and 2.65%, respectively. The accuracy and robustness of the proposed system coupled with its inherent simplicity and ability to display real-time results on a self-designed website establish itself as a potent tool for water quality monitoring purpose.

In this research, a theoretical perception on the notion of an ultra-high sensitive evanescent wave-based fiber-optic refractive index sensor has been proposed by shining an optical Airy beam. The sensing configuration consists of a multimode fiber which is decladded from the middle to aptly sculpt the evanescent wave. In presence of the Airy beam, effectual coupling of high-order modes within the sensing structure has been affirmed by using the classical wave-optic model. To corroborate our theoretical study, an Eigenmode expansion solver (EME) propagation analysis was conducted in commercially offered Mode solution software (Lumerical Inc.) to investigate the transmission characteristics of Airy beam within the waveguide structure. Compared with conventional Gaussian beam-based sensor, the proposed refractive index sensor renders a maximum 19.15 fold superior sensitivity of 992.39 dB/RIU with an admirable sensing resolution of ∼1.00 × 10−5 RIU. Thus, this nascent-class of beam called Airy beam manifests a new degree of freedom which demonstrates the viability of the proposed scheme for the usage of chemical and biological sensing.

This work proposes a novel and highly-sensitive optical device to sense the presence of different pathogenic bacteria in drinking water. The initial sensing structure consists of a decladded multimode fiber with a higher order Bessel-Gauss beam shining on it. It relies on the notion of intermodal interference, where the transmitted output power varies with changeable cladding refractive index because of different pathogenic bacteria as present in the water sample. For the designing of bacteria sensor, such coalescence of higher order Bessel-Gauss beam along with a decladded multimode fiber has never been mentioned in any of the existing literatures. The device's sensing behavior was substantiated using a finite difference Eigenmode analysis in Mode solution software (commercially available from Lumerical Inc., Canada). By selecting the sensing length as 7 cm, the obtained spectral sensitivity of 1179 dB/RII is 3.78 times superior to the typical Gaussian sensor. Therefore such an emerging beam known as higher-order beam Bessel-Gauss offers new prospects in the biosensing field.

Curiosity in the properties of non-Gaussian beam-based optical devices has seen a recent resurgence on account of large volume of higher order modes as supported by the platform. By harnessing the advantages of higher-order Bessel-Gauss beam, the present research unveils the concept of an extremely-sensitive optical sensor to detect the limit of kerosene adulteration in petrol. The sensory method works on the concept of modal interference, in which the transmitted power differs with changeable cladding refractive index as induced by the varying kerosene concentration in petrol. To corroborate this, the commercially available Lumerical's Mode solution software and its Eigenmode expansion solver were exploited to investigate the transmitting property of the sensing device. If the sensing length is set to 7 cm, the procured average sensitivity of 0.41 dB/% is 4.1-fold higher in contrast to the typical Gaussian beam-shined sensor. The presence of ~0.02% kerosene contaminant in petrol can be sensed with the proposed methodology, while the conventional Gaussian beam-shined technology is able to sense the presence of ~0.10% of the same. Therefore such a nascent-class of beam called higher-order Bessel-Gauss beam accelerates new possibilities in the area of fiber optic sensing and can be useful in various petrochemical and automotive industries.

Bend-induced loss in microbending fiber-optic sensor has proved to be an effective one for the direct and indirect measurement of various physical parameters. In this research, a novel and highly sensitive microbend sensor has been explored by launching a zero order Bessel-Gauss beam inside a waveguide arrangement having a No-core fiber bonded amidst two special higher-order mode supporting fibers. By harnessing the special characteristics of the Bessel-Gauss beam, pairing of manifold high-order modes has been affirmed inside the sensor structure. The captivating feature of such sensor is that it defies the conventional wisdom and significantly improves the sensitivity without any intricate fabrication techniques like in tapering, bending etc. To our knowledge, such realization of Bessel-Gauss beam-shined microbend sensor has not been reported earlier in any of the contemporary literature. In support of our theoretical analysis; a Beam propagation method is employed in OptiBPM software (Optiwave Systems Inc.) to envisage the full transmission spectrum of the waveguide. For different bend radii, the sensor response has been numerically investigated and it is anticipated that the sensitivity is expected to be enhanced by a gentle reduction in the bend radius. With the presence of six microbends, the proposed sensor manifests an average bend sensitivity of 2.8 dB/mm which is 3.2 times superior to the classical microbend sensing configuration. Due to such superior sensing performance, the present paradigm paves the way for many potential applications, like damage detection of various engineering structures, and measurement of different physical parameters like temperature and pressure.

This research explores the possibility of using non-Gaussian class of beam like Bessel-Gauss beam towards the investigation of a highly-sensitive modal interference-based salinity sensor. Such fiber-optic sensor involves a No-core fiber which is being spliced amid two specialty higher order mode supporting fibers. The main motivation behind our proposed work is that Bessel-Gauss beam has higher amount of energy at the beam's edge which will create larger overlap between the guided modes with the sensing medium without any complex fabrication process. By harnessing such advantages of Bessel-Gauss beam, the efficient excitation of various high-order linearly polarized modes within the sensor structure has been analyzed with emphasis on the coupled mode theory (CMT). To corroborate this, a detailed optical modeling and simulation study on the proposed sensing scheme was performed in mode solutions software (Lumerical Inc, Canada) to predict the propagation behavior of Bessel-Gauss beam within the waveguide structure. Owing to a large number of high-order mode coupling, the proposed sensor unveils a 3.12 fold superior sensitivity as compared to the conventional Gaussian beam-based sensor, with a commendable sensing resolution of 0.005%. Moreover, a detailed simulation study has been executed to examine the sensor behavior for various No-core fiber radii, and axicon apex angles. As the proposed all-fiber salinity sensor features the advantages of higher sensitivity and better sensing resolution, so it has a great prospect in any physical, biological or chemical sensing needs.

In this research, an ultra-high sensitive multimode interference-based fiber-optic temperature sensor is unveiled by radiating with a Vortex beam. The efficient excitation of several high-order modes within the waveguide structure has been affirmed by using the classical wave-optic model. By exploiting the advantages of Vortex beam, the difference in transmitted output power is determined for various surrounding temperatures, ranging from 28 °C–100 °C. To corroborate our theoretical study, an Eigenmode expansion solver (EME) propagation analysis has been carried out in commercially offered Mode solution software (Lumerical Inc.) to investigate the propagation characteristics of Vortex beam inside the waveguide structure. Our simulation outcome reflects a maximal temperature sensitivity of 0.14 dB/°C with a commendable sensing resolution of ∼0.07 °C. When compared to the conventional Gaussian beam-based sensor, such sensitivity of the proposed temperature sensor was found to be enhanced by a factor of about 3.5. Finally, we presented the systematic study describing the impact of fiber radius, order of Vortex beam, and waist size of input field on the sensor response. On account of such superior sensing performance, the proposed idea expedites new possibilities in any sort of physical, chemical or biological sensing needs.

By using the concept of multimode-interference, an ultra-high sensitive fiber optic strain sensor is conceptualized theoretically through the use of a Bessel-Gauss beam. In presence of such non-Gaussian beam, effectual coupling of high-order modes within the sensing structure has been affirmed by using the classical wave-optic model. To corroborate our theoretical study, an Eigenmode expansion solver (EME) propagation analysis was conducted in commercially offered Lumerical Mode solution software to analyze the properties of Bessel-Gauss beam propagation within the waveguide system. Our simulation outcome reveals that the projected sensing system has 3.5 times greater sensitivity than the conventional sensor focused on Gaussian beam. In addition, the influence of No-core fiber radius on the sensing performance was also studied in detail. Due to this high-performance feature, the proposed sensing configuration expedites a new avenue in various industrial and process control applications.

We present a theoretical perspective on the notion of a highly sensitive multimode fiber optic evanescent wave absorption-based sensor by exploiting a zero-order Bessel-Gauss beam to determine the concentration of sodium chloride (NaCl) from its aqueous solution. The phenomenon of excited waveguide modes inside the sensor structure has been assessed by using a classical wave-optic model. By harnessing the advantages of the Bessel-Gauss beam, the difference in transmitted output power is evaluated for various concentrations of NaCl, ranging from 0 to 360 g/L. To corroborate our theoretical predictions, the computer-aided simulation in Mode Solutions software has been performed on the proposed sensing configuration. In contrast to the conventional concentration sensor using Gaussian beam, the projected scheme yields a maximum 14.40-fold superior sensitivity of 0.072 dB/gL-1 with a commendable sensing resolution of ∼0.013 g/L. Also, attention has been paid to the Bessel-Gauss beam shined U-bent fiber-optic absorption-based concentration sensor, where the sensor response has been numerically investigated for different bending radii, and it is concluded that the sensitivity can be enhanced appreciably by gently reducing the bending radius. Due to ultrahigh sensitivity, the present paradigm is very much alluring and evocative, establishing pivotal implication in chemical and biological sensing fields.

A proposal toward the enhancement in the sensitivity of a multimode interference-based fiber optic liquid-level sensor is explored analytically using a zero-order Bessel-Gauss (BG) beam as the input source. The sensor head consists of a suitable length of no-core fiber (NCF) sandwiched between two specialty high-order mode fibers. The coupling efficiency of various order modes inside the sensor structure is assessed using guided-mode propagation analysis and the performance of the proposed sensor has been benchmarked against the conventional sensor using a Gaussian beam. Furthermore, the study has been corroborated using a finite-difference beam propagation method in Lumerical's Mode Solutions software to investigate the propagation of the zero-order BG beam inside the sensor structure. Based on the simulation outcomes, the proposed scheme yields a maximum absolute sensitivity of up to 3.551dB/mm and a sensing resolution of 2.816×10 -3 mm through the choice of an appropriate length of NCF at an operating wavelength of 1.55μm. Owing to this superior sensing performance, the reported sensing technology expedites an avenue to devise a high-performance fiber optic-level sensor that finds profound implication in different physical, biological, and chemical sensing purposes.

A novel fiber optic multimode interference based refractive index sensor by shining zeroth order Bessel-Gauss beam is reported and investigated. The proposed sensing scheme offers a 9.22 times higher sensitivity and an improved refractive index sensing resolution in the magnitude of around tenth order than the sensor using Gaussian beam.

A highly sensitive multimode-interference-based refractive index sensor is reported here by shining an optical vortex beam. The sensor probe is formed by splicing a length of no-core fiber in between two air-core vortex fibers. The coupling characteristics of various modes inside the sensor and their effect on sensing properties are numerically analyzed. Simulation results show that the sensing scheme proffers a maximum sensing resolution of 7.59 × 10−6 and 4.18 × 10−6 RIU for no-core fiber length of 29.40 and 44.60 mm, respectively. Because of its high sensitivity, the study has potential applications in the chemical and biological sensing fields.

A novel multimode interference-based refractive index sensor in a higher-order-mode-no-core-higherorder- mode fiber structure achieved by shining a zero-order Bessel-Gauss beam is reported here. The effect of higher-order mode coupling on the performance of the proposed sensor is investigated and verified numerically. Based on the simulation results, the proposed sensing scheme offers a very high sensing resolution of 5.54 × 10-6 RIU over the refractive index range of 1.33-1.42 for a no-core fiber length of 15 mm. So, the sensor we proposed has significant advantages in the field of any physical, biological, and chemical sensing purposes as it provides measurement with very high sensitivity.

A novel fiber optic multimode interference based refractive index sensor by shining zeroth order Bessel-Gauss beam is reported and investigated. The proposed sensing scheme offers a 9.22 times higher sensitivity and an improved refractive index sensing resolution in the magnitude of around tenth order than the sensor using Gaussian beam.

A novel fiber optic temperature sensor based on single-mode-No-core-single-mode fiber structure by shining zeroth order Bessel-Gauss beam into it is reported. This scheme offers 55.23 times higher sensitivity than the sensor using Gaussian beam.