Search Results (12)

In recent years, unidimensional photonic crystal-based biosensors have attracted significant attention due to their potential for label-free bio-detection of cells, proteins, and other organic molecules. These biosensors are based on alternating materials with different refractive indices and a cavity region in which biomolecules can be injected. In this study, we investigated numerically the optical properties of unidimensional photonic crystals based on [LiTaO₃/MgF₂], [LiTaO₃/SiO₂], [PbTiO₃/MgF₂], and [PbTiO₃/SiO₂] heterostructures, and focused our discussion on the detection of four kinds of extracellular vesicles. Our results demonstrated that the [PbTiO₃/MgF₂] photonic crystal biosensor exhibited the best biosensing performance, with a maximum value of the sensitivity of 511.3 nm/RIU. This study provides valuable insights into the use of perovskites materials, in particular, LiTaO₃ and PbTiO₃ for photonic crystal-based biosensors for various applications, including disease diagnosis and monitoring therapy responses. Full article

A new design of a bio-random laser based on a butterfly wing structure and ITO glass is proposed in this article. Firstly, the butterfly wing structure was integrated in a liquid crystal cell made of ITO glass. The integrated liquid crystal cell was injected with liquid crystal and dye to obtain a bio-random laser. A non-biological random laser was obtained with a capillary glass tube, liquid crystal and dye. The excitation spectra and thresholds were recorded to evaluate the performance of the biological and non-biological random lasers. The results show that the excitation performance stability of the bio-random laser is improved and the number of spikes in the spectra is reduced compared with the non-biological random laser. Finally, the equivalent cavity length of the biological and non-biological random lasers was compared and the optical field distribution inside the butterfly wing structure was analyzed. The data show that the improvement of the excitation performance stability of the bio-random laser is related to the localization of the optical field induced by the photonic crystal structure in the butterfly wing. Full article

It is very important to design a rapid and sensitive device for the creatinine concentration detection due to it being one of the most considerable benchmarks for efficient kidney working. Here, a novel biophotonic sensor using one-dimensional ternary PC based on Si/TiN/SiO₂ layers is proposed for the creatinine concentration detection in a blood serum sample. A central cavity layer is inserted between two equal periodic numbers. The blood sample can be infiltrated in the cavity layer with various creatinine concentrations. Based on the technique of transfer matrix, the transmittance spectra properties are investigated. The influences of variation of the incidence angle for both TE and TM polarizations and the cavity layer thickness are carefully investigated to attain the best sensitivity of the biophotonic detector. A high sensitivity of 938.02 nm/RIU is realized for the suggested detector, which is comparable to most recent works published in this area. Moreover, the proposed sensor has an inexpensive cost, real-time detection, and simple structure, which is helpful to the industrial design using low-cost product nanofabrication techniques. Based on above-mentioned outcomes, our biosensor candidate is a suitable and effective device for the detection of creatinine concentration, and it can use for any biological sample. Full article

The present research work focused on the biosensing capabilities of one-dimensional (1D) defected photonic crystal (PC). This proposed structure is capable of simultaneously discriminating between normal and infected samples containing the platelet, plasma, and hemoglobin components of blood. The proposed biosensor was designed by creating a defect layer D of air in the middle of 1D PC (PQ)^N to form modified 1D PC with a defect as (PQ)^N/2D(PQ)^N/2. The period number (N) of 1D PC (PQ)^N was chosen to be 10. The cavity region of air was used to investigate only one of the five samples, at each time, that are part of this study. The theoretical findings of the proposed work were obtained using the well-known transfer matrix method in addition to MATLAB software. The results were computed corresponding to defect layer thicknesses of 200 and 700 nm under normal incidence to overcome the difficulties associated under oblique incidence corresponding to TE and TM polarized waves. We examined the performance of the proposed design by calculating the sensitivity, figure of merit, and quality factor values of the biophotonic sensor loaded with different samples. It was found that the sensitivity of our design reaches to a maximum of 428.6 nm/RIU corresponding to the defect layer thickness of 700 nm, when the cavity is loaded with an infected blood sample containing plasma only. This study successfully simultaneously examined the normal and infected blood samples containing the platelet, plasma, and hemoglobin components of blood. Full article

The present research is focused on the externally tunable defect mode properties of a one dimensional (1D) defective photonic crystal (DPhC) for fast detection of cancerous brain tumors. The proposed design has utilized conventional 1D DPhC whose cavity is coated with SiO₂ nanoparticles embedded in a superconducting material layer called a nanocomposite layer. The purpose of a nanocomposite superconducting layer is to induce temperature dependent external tuning of the defect mode inside PBG, in addition, to changing in the angle of incidence. The inclusion of a nanocomposite layer also improves the interaction between light and different brain tissue samples under examination. In order to investigate the transmission properties of the proposed structure the transfer matrix formulation in addition to the MATLAB computational tool has been used. First, we have chosen the optimized internal parameters at normal incidence to obtain the maximum performance of the design. Secondly, the effect of change in angle of incidence has been studied to further increase the performance by means of sensitivity, quality factor, the figure of merit and limit of detection to ensure external tuning of defect mode. After achieving a maximum value of sensitivity (4139.24 nm/RIU) corresponding to a sample containing a wall of brain tissues at θ = 63° we have further investigated the effect of change in temperature of nanocomposite layers on the position and intensity both of the defect mode inside PBG. We have found that the increase in temperature results in minute changes in sensitivity but a significant increase in the intensity of defect mode which is highly required in any photonic biosensing design. The findings of this study may be very useful for designing various bio-sensing structures which could have a significant and decisive role in the field of biomedical applications. Full article

A bio-photonic cavity quantum electrodynamic (C-QED) framework could be imagined as a system in which both the “cavity” and the “atom” participating in the light-matter interaction scenario are bio-inspired. Can a cavity be made of a bio-polymer? If so, how should such a cavity appear and what are the best polymers to fabricate it? Can a bioluminescent material stand the comparison with new-fashion semiconductors? In this review we answer these fundamental questions to pave the way toward an eco-friendly paradigm, in which the ever-increasing demand for more performing quantum photonics technologies meets the ever-increasing yet silent demand of our planet to reduce our environmental footprint. Full article

The consolidation of laser micro/nano processing technologies has led to a continuous increase in the complexity of optical fiber sensors. This new avenue offers novel possibilities for advanced sensing in a wide set of application sectors and, especially in the industrial and medical fields. In this review, the most important transducing structures carried out by laser processing in optical fiber are shown. The work covers different types of fiber Bragg gratings with an emphasis in the direct-write technique and their most interesting inscription configurations. Along with gratings, cladding waveguide structures in optical fibers have reached notable importance in the development of new optical fiber transducers. That is why a detailed study is made of the different laser inscription configurations that can be adopted, as well as their current applications. Microcavities manufactured in optical fibers can be used as both optical transducer and hybrid structure to reach advanced soft-matter optical sensing approaches based on optofluidic concepts. These in-fiber cavities manufactured by femtosecond laser irradiation followed by chemical etching are promising tools for biophotonic devices. Finally, the enhanced Rayleigh backscattering fibers by femtosecond laser dots inscription are also discussed, as a consequence of the new sensing possibilities they enable. Full article

We provide here an overview of passive optical micro-cavities made of droplets in the liquid phase. We focus on resonators that are naturally created and suspended under gravity thanks to interfacial forces, illustrating simple ways to excite whispering-gallery modes in various slow-evaporation liquids using free-space optics. Similar to solid resonators, frequency locking of near-infrared and visible lasers to resonant modes is performed exploiting either phase-sensitive detection of the leakage cavity field or multiple interference between whispering-gallery modes in the scattered light. As opposed to conventional micro-cavity sensors, each droplet acts simultaneously as the sensor and the sample, whereby the internal light can detect dissolved compounds and particles. Optical quality factors up to 107–108 are observed in liquid-polymer droplets through photon lifetime measurements. First attempts in using single water droplets are also reported. These achievements point out their huge potential for direct spectroscopy and bio-chemical sensing in liquid environments. Finally, the first experiments of cavity optomechanics with surface acoustic waves in nanolitre droplets are presented. The possibility to perform studies of viscous-elastic properties points to a new paradigm: a droplet device as an opto-fluid-mechanics laboratory on table-top scale under controlled environmental conditions. Full article

Particle trapping and sensing serve as important tools for non-invasive studies of individual molecule or cell in bio-photonics. For such applications, it is required that the optical power to trap and detect particles is as low as possible, since large optical power would have side effects on biological particles. In this work, we proposed to deploy a nanobeam photonic crystal cavity for particle trapping and opto-mechanical sensing. For particles captured at 300 K, the input optical power was predicted to be as low as 48.8 μW by calculating the optical force and potential of a polystyrene particle with a radius of 150 nm when the trapping cavity was set in an aqueous environment. Moreover, both the optical and mechanical frequency shifts for particles with different sizes were calculated, which can be detected and distinguished by the optomechanical coupling between the particle and the designed cavity. The relative variation of the mechanical frequency achieved approximately 400%, which indicated better particle sensing compared with the variation of the optical frequency (±0.06%). Therefore, our proposed cavity shows promising potential as functional components in future particle trapping and manipulating applications in lab-on-chip. Full article

The availability of silicon photonic integrated circuits (ICs) in the 2–4 μm wavelength range enables miniature optical sensors for trace gas and bio-molecule detection. In this paper, we review our recent work on III–V-on-silicon waveguide circuits for spectroscopic sensing in this wavelength range. We first present results on the heterogeneous integration of 2.3 μm wavelength III–V laser sources and photodetectors on silicon photonic ICs for fully integrated optical sensors. Then a compact 2 μm wavelength widely tunable external cavity laser using a silicon photonic IC for the wavelength selective feedback is shown. High-performance silicon arrayed waveguide grating spectrometers are also presented. Further we show an on-chip photothermal transducer using a suspended silicon-on-insulator microring resonator used for mid-infrared photothermal spectroscopy. Full article

Nanophotonic technique has been attracting much attention in applications of nano-bio-chemical sensing and energy conversion of solar energy harvesting and enhanced energy transfer. One approach for nano-bio-chemical sensing is surface plasmon resonance (SPR) imaging, which can detect the material properties, such as density, ion concentration, temperature, and effective refractive index in high sensitivity, label-free, and real-time under ambient conditions. Recent study shows that SPR can successfully detect the concentration variation of nanofluids during evaporation-induced self-assembly process. Spoof surface plasmon resonance based on multilayer metallo-dielectric hyperbolic metamaterials demonstrate SPR dispersion control, which can be combined with SPR imaging, to characterize high refractive index materials because of its exotic optical properties. Furthermore, nano-biophotonics could enable innovative energy conversion such as the increase of absorption and emission efficiency and the perfect absorption. Localized SPR using metal nanoparticles show highly enhanced absorption in solar energy harvesting. Three-dimensional hyperbolic metamaterial cavity nanostructure shows enhanced spontaneous emission. Recently ultrathin film perfect absorber is demonstrated with the film thickness is as low as ~1/50th of the operating wavelength using epsilon-near-zero (ENZ) phenomena at the wavelength close to SPR. It is expected to provide a breakthrough in sensing and energy conversion applications using the exotic optical properties based on the nanophotonic technique. Full article

We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm) of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly. Full article