Metal-insulator-metal waveguide-based optical pressure sensor embedded with arrays of silver nanorods

Ultra-high-sensitive plasmonic sensor based on asymmetric hexagonal nano-ring resonator for cancer detection

A highly sensitive sensor based on two metal-insulator-metal waveguides coupled to an asymmetric hexagonal nano-ring resonator detecting cancerous cells is proposed. This novel design is utilized to facilitate the sensing of human cells. The sensing mechanism of the presented optical structure can act as a refractive index measurement in biological, chemical, biomedical diagnosis, and bacteria detection, which leads to achieving high sensitivity in the structure. The main goal is to achieve the highest sensitivity concerning the optimum design. As a result, the sensitivity of the designed topology reaches a maximum value of about 1800 nm/RIU (nm/refractive index unit) by controlling the angle of the resonator. It is evident that the sensitivity parameter is improved, and the reason for the increase in sensitivity is due to the asymmetry of the resonator, which has an 81 % increase in sensitivity compared to the symmetrical resonator, especially for blood cancer cells. The maximum quality factor obtains 131.65 with a FOM of 90.4 (RIU-1). The sensing performance of this proposed structure is numerically investigated using the finite difference time domain (FDTD) method with the perfectly matched layer (PML). Accordingly, the suggested high sensitivity sensor makes this structure a promising therapeutic candidate for sensing applications that can be used in on-chip optical devices to produce highly complex integrated circuits.

Plasmonic nanosensor and pressure-induced transparency based on coupled resonator in a nanoscale system

Plasmonic nanosensors and the dynamic control of light fields are of the utmost significance in the field of micro- and nano-optics. Here, our study successfully demonstrates a plasmonic nanosensor in a compact coupled resonator system and obtains the pressure-induced transparency phenomenon for the first time to our knowledge. The proposed structure consists of a groove and slot cavity coupled in the metal-insulator-metal waveguide, whose mechanical and optical characteristics are investigated in detail using the finite element method. Simulation results show that we construct a quantitative relationship among the resonator deformation quantity, the applied pressure variation, and the resonant wavelength offset by combining the mechanical and optical properties of the proposed system. The physical features contribute to highly efficient plasmonic nanosensors for refractive index and optical pressure sensing with sensitivity of 1800 nm/RIU and 7.4 nm/MPa, respectively. Furthermore, the light waves are coupled to each other in the resonators, which are detuned due to the presence of pressure, resulting in the pressure-induced transparency phenomenon. It is noteworthy to emphasize that, unlike previously published works, our numerical results take structural deformation-induced changes in optical properties into account, making them trustworthy and practical. The proposed structure introduces a novel, to the best of our knowledge, approach for the dynamic control of light fields and has special properties that can be utilized for the realization of various integrated components.

Tunable electromagnetically induced absorption based on coupled-resonators in a compact plasmonic system

Electromagnetically induced absorption (EIA) exhibits abnormal dispersion and novel fast-light features, making it a crucial aspect of nanophotonics. Here, the EIA phenomenon is numerically predicted in a compact plasmonic waveguide system by introducing a slot resonator above a square cavity. Simulation results reveal that the EIA response can be easily tuned by altering the structure's parameters, and double EIA valleys can be observed with an additional slot resonator. Furthermore, the investigated structures demonstrate a fast-light effect with an optical delay of ∼ -1.0 ps as a result of aberrant dispersion at the EIA valley, which enable promising applications in the on-chip fast-light area. Finally, a plasmonic nanosensor with a sensitivity of ∼1200 nm/RIU and figure of merit of ∼16600 is achieved based on Fano resonance. The special features of our suggested structure are applicable in realization of various integrated components for the development of multifunctional high-performance nano-photonic devices.

Pressure and temperature dual-parameter optical sensor based on the MIM waveguide structure coupled with two T-shaped cavities

This paper elaborates on the design and simulation of a multifunctional optical sensor that features simultaneous detection of pressure and temperature, which is based on the metal-insulator-metal waveguide structure with two T-shaped resonant cavities. Depending on the simulation findings, pressure and temperature can be measured separately by two T-shaped cavities at different Fano resonance wavelengths. As the pressure applied to the upper T-shaped cavity increases, the resonance wavelength first shifts linearly due to the slight deformation of the cavity, and the maximum pressure sensitivity reaches 12.48 nm/MPa. After the pressure exceeds a threshold, the relationship between pressure and resonance wavelength transforms into a quadratic polynomial. In the lower T-shaped cavity, solid polydimethylsiloxane is sealed as a thermal-sensitive material, effectively preventing material overflow brought on by structural micro-vibration under pressure, and its high thermo-optical coefficient prompts a temperature sensitivity of 0.36 nm/°C. Furthermore, by optimizing the choice of Fano resonances, pressure and temperature can be sensed independently without mutual interference. The designed sensor provides extensive application possibilities for scenarios where multiparameter monitoring is required.

Highly sensitive asymmetric and symmetric cancer sensors with ultra-high-quality factor and resolution power

In the paper, we proposed two new highly sensitive and compact biosensors with ultra-high-quality factors based on the 1-D binary photonic crystal (silicon/air thin layer) with a defect layer. The proposed asymmetric and symmetric biosensors have just a few periods (two to five) on both sides of the defect layer and the normal cell group (INOK) and cancer cells group (YD-10B) are considered for the studies. The effects of different parameters including silicon layer thickness, air layer thickness, defect layer thickness, substrate position, number of periods, and light incident angle are considered in the biosensor operation and the biosensors are optimized based on the sensitivity. The results demonstrate that the sensitivity and defect mode wavelength of the sensors are independent of the substrate position. However, the quality factor and FOM of the sensors significantly depend on the substrate position and they are improved significantly in the symmetric sensor (~ 37% improvement in optimum condition). Also, the high sensitivities of the sensors are maintained over a wide range of silicon and air thicknesses, which is a valuable achievement in the manufacturing process. Furthermore, the sensitivity of the optimized biosensors with a defect layer thickness of 10 microns and only two periods reaches S ~ 2811 nm/RIU which is an excellent sensitivity for an optical biosensor.

ZrN-based plasmonic sensor: a promising alternative to traditional noble metal-based sensors for CMOS-compatible and tunable optical properties

In this article, we introduce a novel comb shaped plasmonic refractive index sensor that employs a ZrN-Insulator-ZrN configuration. The sensor is constructed using Zirconium Nitride (ZrN), an alternative refractory material that offers advantages over traditional metals such as silver and gold, as ZrN is standard Complementary Metal Oxide Semiconductor (CMOS)-compatible and has tunable optical properties. The sensor has recorded a maximum sensitivity, figure of merit (FOM), and sensing resolution of 1445.46 nm/RIU, 140.96, and 6.91 × 10-7RIU-1, respectively. Beyond that, the integration of ZrN offers the sensor with various advantages, including higher hardness, thermal stability at high temperatures, better corrosion and abrasion resistance, and lower electrical resistivity, whereas traditional plasmonic metals lack these properties, curtailing the real-world use of plasmonic devices. As a result, our suggested model surpasses the typical noble material based Metal-Insulator-Metal (MIM) arrangement and offers potential for the development of highly efficient, robust, and durable nanometric sensing devices which will create a bridge between nanoelectronics and plasmonics.

A Review on Photonic Sensing Technologies: Status and Outlook

In contemporary science and technology, photonic sensors are essential. They may be made to be extremely resistant to some physical parameters while also being extremely sensitive to other physical variables. Most photonic sensors may be incorporated on chips and operate with CMOS technology, making them suitable for use as extremely sensitive, compact, and affordable sensors. Photonic sensors can detect electromagnetic (EM) wave changes and convert them into an electric signal due to the photoelectric effect. Depending on the requirements, scientists have found ways to develop photonic sensors based on several interesting platforms. In this work, we extensively review the most generally utilized photonic sensors for detecting vital environmental parameters and personal health care. These sensing systems include optical waveguides, optical fibers, plasmonics, metasurfaces, and photonic crystals. Various aspects of light are used to investigate the transmission or reflection spectra of photonic sensors. In general, resonant cavity or grating-based sensor configurations that work on wavelength interrogation methods are preferred, so these sensor types are mostly presented. We believe that this paper will provide insight into the novel types of available photonic sensors.

Sensitivity-enhanced optical pressure sensor based on MoS2

A sensitivity-enhanced optical pressure sensor based on molybdenum disulfide (MoS₂) is proposed. The sensing principle is that the pressure causes the deformation of the polydimethylsiloxane (PDMS) pressure structure above the MoS₂ film, leading to the change of the ambient refractive index, so that a measurable light propagation difference in the waveguide under the film is created to reflect the micro changes of the pressure. The pressure is finally numerically converted to the wavelength shift of the interference peak of the obtained spectrum. The process is simulated and analyzed using MoS₂ dielectric film, in contrast with that using graphene dielectric film. It turns out that under same conditions, the MoS₂ film has a more distinct modulation effect on light than that of the graphene film. Experiments using the real sensor prototype are carried out and the results show that the pressure measuring sensitivity is improved to 96.02 nm/kPa in the pressure range of 0-0.6 kPa, which is much higher than the typical optical pressure sensors. The proposed optical pressure sensor based on MoS₂ is of high potential to support ultra-sensitive pressure detection in many applications.

A Multi-Layered Borophene-Silica-Silver Based Refractive Index Sensor for Biosensing Applications Operated at the Infrared Frequency Spectrum

We have presented the borophene based refractive index sensor for the infrared frequency spectrum of 188 to 250 THz (1.2–1.6 µm) range. The proposed structure was formed by using the Silver-borophene-silica-Ag layered structure. The behaviour of the different analyte (with a different refractive index) material is numerically calculated by placing it on the top of the structure. The behaviour of the structure is identified in terms of absorption, reflectance, physical parameter variation, and oblique angle incident conditions. The presented results provide the basic idea of selecting optimized structure dimensions to get the specific resonating response. This sensor offers the Figure of Merit (FOM) of 444 RIU−1 with high sensitivity of 660 THz/RIU (4471 nm/RIU). The refractive index sensor also provides wide-angle stability for (0° to 80°) for the wide frequency range (239 to 245 THz and 207 to 209 THz). This sensor is developed on the silver metal layer (not required to separate borophene from its origin metal deposition process) and easily fabricated using standard boron fabrication and layered deposition techniques. The results of the proposed structure make it possible to design a basic biosensor structure. This device is also applicable for various THz and biomedical applications.

Dual-mode independent detection of pressure and refractive index by miniature grating-coupled surface plasmon sensor

Multiple parameters need to be monitored to analyze the kinetics of biological progresses. Surface plasmon polariton resonance sensors offer a non-invasive approach to continuously detect the local change of refractive index of molecules with high sensitivity. However, the fabrication of miniaturized, compact, and low-cost sensors is still challenging. In this paper, we propose and demonstrate a grating-coupled SPR sensor platform featuring dual mode operation for simultaneous sensing of pressure and refractive index, which can be fabricated using a highly-efficient low-cost method, allowing large-scale production. Both sensing functionalities are realized by optical means via monitoring the spectral positions of a surface plasmon polariton mode (for refractive index sensing) and Fabry-Perot or metal-insulator-metal modes (for pressure sensing), which are supported by the structure. Simultaneous measurement of refractive index with the sensitivity of 494 nm/RIU and pressure was demonstrated experimentally. The proposed platform is promising for biomonitoring that requires both high refractive index sensitivity and local pressure detection.

Enhancement of Sensitivity with High-Reflective-Index Guided-Wave Nanomaterials for a Long-Range Surface Plasmon Resonance Sensor

A guided−wave long−range surface plasmon resonance (GW−LRSPR) sensor was proposed in this investigation. In the proposed sensor, high−refractive−index (RI) dielectric films (i.e., CH₃NH₃PbBr₃ perovskite, silicon) served as the guided−wave (GW) layer, which was combined with the long−range surface plasmon resonance (LRSPR) structure to form the GW−LRSPR sensing structure. The theoretical results based on the transfer matrix method (TMM) demonstrated that the LRSPR signal was enhanced by the additional high#x2212;RI GW layer, which was called the GW−LRSPR signal. The achieved GW−LRSPR signal had a strong ability to perceive the analyte. By optimizing the low− and high−RI dielectrics in the GW−LRSPR sensing structure, we obtained the highest sensitivity (S) of 1340.4 RIU⁻¹ based on a CH₃NH₃PbBr₃ GW layer, and the corresponding figure of merit (FOM) was 8.16 × 10⁴ RIU⁻¹ deg⁻¹. Compared with the conventional LRSPR sensor (S = 688.9 RIU⁻¹), the sensitivity of this new type of sensor was improved by nearly 94%.

Ultrahigh Sensitivity of a Plasmonic Pressure Sensor with a Compact Size

This study proposes a compact plasmonic metal-insulator-metal pressure sensor comprising a bus waveguide and a resonator, including one horizontal slot and several stubs. We calculate the transmittance spectrum and the electromagnetic field distribution using the finite element method. When the resonator's top layer undergoes pressure, the resonance wavelength redshifts with increasing deformation, and their relation is nearly linear. The designed pressure sensor possesses the merits of ultrahigh sensitivity, multiple modes, and a simple structure. The maximum sensitivity and resonance wavelength shift can achieve 592.44 nm/MPa and 364 nm, respectively, which are the highest values to our knowledge. The obtained sensitivity shows 23.32 times compared to the highest one reported in the literature. The modeled design paves a promising path for applications in the nanophotonic field.

Cog-shaped refractive index sensor embedded with gold nanorods for temperature sensing of multiple analytes

This article presents a refractive index (RI) nanosensor utilizing gold as the plasmonic material. The layout of the sensor includes metal-insulator-metal (MIM) waveguides coupled with a cog-shaped resonator studded with gold nanorods. At the mid-infrared (MIR) spectrum, the spectral characteristics of the sensor are numerically analyzed employing the finite element method (FEM). Moreover, the refractive index sensing property is thoroughly explored by varying the key parameters, establishing a linear correlation with the transmittance profile. After extensive simulations, the most optimum structure displays the highest sensitivity of 6227.6 nm/RIU. Furthermore, the capability of the proposed device as a temperature sensor is investigated with five different liquids (ethanol, polydimethylsiloxane, toluene, chloroform, and the mixture of toluene and chloroform); among these, chloroform exhibits maximum temperature sensitivity of 6.66 nm/°C. Due to being chemically stable and demonstrating satisfactory performance in RI and temperature sensing, the suggested schematic can be a suitable replacement for silver-based sensors.