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.

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.

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.

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.

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.

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.

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.

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.

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.