Showing papers on "Photonic-crystal fiber published in 2018"

A Novel Approach for Spectroscopic Chemical Identification Using Photonic Crystal Fiber in the Terahertz Regime

Abstract: A novel highly sensitive porous core-photonic crystal fiber (PC-PCF) has been designed and analyzed for detection of chemical analytes in the terahertz frequency range. The PC-PCF is designed using rectangular structured air holes in the core with a kagome structured cladding. The full vectorial finite-element method is used to tune the geometrical parameters and to characterize the fiber. Our results demonstrate a high relative chemical sensitivity with significantly lower confinement loss for different analytes. Moreover, the PCF shows near zero dispersion variation, high modal effective area, high birefringence, and high numerical aperture. The practical realization of the fiber is feasible with present fabrication techniques. Our optimized PCF has commercial applications in chemical sensing as well as applications in terahertz systems that require guided polarization preserving transmission.

Symmetrical dual D-shape photonic crystal fibers for surface plasmon resonance sensing.

Abstract: Symmetrical dual D-shape photonic crystal fibers (PCFs) for surface plasmon resonance (SPR) sensing are designed and analyzed by the finite element method (FEM). The performance of the sensor is remarkably enhanced by the directional power coupling between the two fibers. We study the influence of the structural parameters on the performance of the sensor as well as the relationship between the resonance wavelengths and analyze refractive indexes between 1.36 and 1.41. An average spectral sensitivity of 14660 nm/RIU can be achieved in this sensing range and the corresponding refractive index resolution is 6.82 × 10-6 RIU. The characteristics of a single D-shape PCF-SPR sensor with the same structural parameters are compared with those of the dual PCFs sensor and the latter has distinct advantages concerning the spectral sensitivity, resolution, amplitude sensitivity, and figure of merits (FOM).

Spiral Photonic Crystal Fiber-Based Dual-Polarized Surface Plasmon Resonance Biosensor

Abstract: We numerically demonstrate a surface plasmon resonance biosensor-based on dual-polarized spiral photonic crystal fiber (PCF). Chemically stable gold material is used as the active plasmonic material, which is placed on the outer layer of the PCF to facilitate practical fabrication. Finite-element method-based numerical investigations show that the proposed biosensor shows maximum wavelength sensitivity of 4600 and 4300 nm/RIU in ${x}$ - and ${y}$ -polarized modes at an analyte refractive index of 1.37. Moreover, for analyte refractive index ranging from 1.33 to 1.38, maximum amplitude sensitivities of 371.5 RIU−1 and 420.4 RIU−1 are obtained in ${x}$ - and ${y}$ -polarized modes, respectively. In addition, the effects of changing pitch, different air hole diameter of the PCF and thickness of the gold layer on the sensing performance are also investigated. Owing to high sensitivity, improved sensing resolution and appropriate linearity characteristics, the proposed dual-polarized spiral PCF can be implemented for the detection of biological analytes, organic chemicals, biomolecules, and other unknown analytes.

Highly sensitive selectively coated photonic crystal fiber-based plasmonic sensor.

Abstract: Highly sensitive and miniaturized sensors are highly desirable for real-time analyte/sample detection In this Letter, we propose a highly sensitive plasmonic sensing scheme with the miniaturized photonic crystal fiber (PCF) attributes A large cavity is introduced in the first ring of the PCFs for the efficient field excitation of the surface plasmon polariton mode and proficient infiltration of the sensing elements Due to the irregular air-hole diameter in the first ring, the cavity exhibits the birefringence behavior which enhances the sensing performance The novel plasmonic material gold has been used considering the chemical stability in an aqueous environment The guiding properties and the effects of the sensing performance with different parameters have been investigated by the finite element method, and the proposed PCFs have been fabricated using the stack-and-draw fiber drawing method The proposed sensor performance was investigated based on the wavelength and amplitude sensing techniques and shows the maximum sensitivities of 11,000 nm/RIU and 1,420 RIU−1, respectively It also shows the maximum sensor resolutions of 91×10−6 and 7×10−6 RIU for the wavelength and amplitude sensing schemes, respectively, and the maximum figure of merits of 407 Furthermore, the proposed sensor is able to detect the analyte refractive indices in the range of 133–142; as a result, it will find the possible applications in the medical diagnostics, biomolecules, organic chemical, and chemical analyte detection

Terahertz detection of alcohol using a photonic crystal fiber sensor.

Abstract: Ethanol is widely used in chemical industrial processes as well as in the food and beverage industry. Therefore, methods of detecting alcohol must be accurate, precise, and reliable. In this content, a novel Zeonex-based photonic crystal fiber (PCF) has been modeled and analyzed for ethanol detection in terahertz frequency range. A finite-element-method-based simulation of the PCF sensor shows a high relative sensitivity of 68.87% with negligible confinement loss of 7.79×10−12 cm−1 at 1 THz frequency and x-polarization mode. Moreover, the core power fraction, birefringence, effective material loss, dispersion, and numerical aperture are also determined in the terahertz frequency range. Owing to the simple fiber structure, existing fabrication methods are feasible. With the outstanding waveguiding properties, the proposed sensor can potentially be used in ethanol detection, as well as polarization-preserving applications of terahertz waves.

Novel optical fiber SPR temperature sensor based on MMF-PCF-MMF structure and gold-PDMS film.

Abstract: Figure 1(c) in [Y. Wang, Optics Express 26, 1910 (2018)] contains an error and is corrected in this erratum.

Surface Plasmon Resonance Sensor Based on a Novel D-Shaped Photonic Crystal Fiber for Low Refractive Index Detection

Abstract: A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance (SPR) is proposed and numerically studied Different from the normal D-shaped structures, we here used an open-ring channel coated with gold film to excite the plamonic modes The coupling properties and sensing performance of this structure are analyzed using finite element method Simulation results indicate that the sensor has a sensing range from 120 to 129 When the analyte refractive index (RI) is above 125, the anti-crossing effect starts to appear, and the peak loss of the loss spectra remains nearly constant with increasing RI The maximum spectral sensitivity of 11055 nm/RIU and high resolution of $905\times 10^{-6}$ RIU can be obtained at 129 For the purpose of optimizing sensing performance, the effects of the structure parameters on the resonant spectra are also studied The excellent sensing performance makes the proposed SPR sensor a competitive candidate in low refractive index detection applications

Photonic Crystal Fiber-Based Refractive Index Sensor for Early Detection of Cancer

Abstract: This paper proposes a novel cancer sensor based on dual core photonic crystal fiber for the detection of cancer cells in cervical, breast, and basal parts. The samples are taken in fluid form and infiltrated into the farmed cavity using selective infiltration method. Each fluid form has its own refractive index values which give the various responses in the transmission and loss spectrum. The spectral shift is obtained by inducing the coupling mechanism between silica core and cancer cell core for its launching input optical field which is investigated by finite element method. The proposed structure is also optimized with its structural dimensional property for enhancing the sensitivity. The sensing performances for the cervical cancer cell are obtained as high as 7916 nm/RIU for $x$ -polarization and 10625 nm/RIU for $y$ -polarization with the detection limit of 0.024. The sensitivity to breast cancer cells for $x$ - and $y$ -polarization is 5714.28 and 7857.14 nm/RIU, respectively, with detection limit of 0.014. Similarly, the sensitivity to basal cells can also reach 4500 nm/RIU for $x$ -polarization and 6000 nm/RIU for $y$ -polarization. To the best of our knowledge, such sensitivities are the highest reported thus so far.

Dual-polarized highly sensitive plasmonic sensor in the visible to near-IR spectrum.

Abstract: We propose and numerically characterize the optical characteristics of a novel photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensor in the visible to near infrared (500-2000 nm) region for refractive index (RI) sensing. The finite element method (FEM) is used to design and study the influence of different geometric parameters on the sensing performance of the sensor. The chemically stable plasmonic material gold (Au) is used to produce excitation between the core and plasmonic mode. On a pure silica (SiO2) substrate, a rectangular structured core is used to facilitate the coupling strength between the core and the surface plasmon polariton (SPP) mode and thus improves the sensing performance. By tuning the geometric parameters, simulation results show a maximum wavelength sensitivity of 58000 nm/RIU (Refractive Index Unit) for the x polarization and 62000 nm/RIU for the y polarization for analyte refractive indices ranging from 1.33 to 1.43. Moreover, we characterize the amplitude sensitivity of the sensor that shows a maximum sensitivity of 1415 RIU-1 and 1293 RIU-1 for the x and y polarizations, respectively. To our knowledge, this is the highest sensitivity for an SPR in published literature, and facilitates future development of sensors for accurate and precise analyte measurement. The sensor also attains a maximum figure of merit (FOM) of 1140 and fine RI resolution of 1.6 × 10-6. Owing to strong coupling strength, high sensitivity, high FOM and improved sensing resolution, the proposed sensor is suited for real-time, inexpensive and accurate detection of biomedical and biological analytes, biomolecules, and organic chemicals.

Analysis of a Surface Plasmon Resonance Probe Based on Photonic Crystal Fibers for Low Refractive Index Detection

Abstract: A photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) probe with gold nanowires as the plasmonic material is proposed in this work. The coupling characteristics and sensing properties of the probe are numerically investigated by the finite element method. The probe is designed to detect low refractive indices between 1.27 and 1.36. The maximum spectral sensitivity and amplitude sensitivity are 6 × 103 nm/RIU and 600 RIU−1, respectively, corresponding to a resolution of 2.8 × 10−5 RIU for the overall refractive index range. Our analysis shows that the PCF-SPR probe can be used for lower refractive index detection.

Mid-infrared multispectral tissue imaging using a chalcogenide fiber supercontinuum source.

Abstract: We present, to the best of our knowledge, the first demonstration of mid-infrared supercontinuum (SC) tissue imaging at wavelengths beyond 5 μm using a fiber-coupled SC source spanning 2–7.5 μm. The SC was generated in a tapered large-mode-area chalcogenide photonic crystal fiber in order to obtain broad bandwidth, high average power, and single-mode output for diffraction-limited imaging performance. Tissue imaging was demonstrated in transmission at selected wavelengths between 5.7 (1754 cm−1) and 7.3 μm (1370 cm−1) by point scanning over a sub-millimeter region of colon tissue, and the results were compared to images obtained from a commercial instrument.

D-shaped photonic crystal fiber plasmonic refractive index sensor based on gold grating

Abstract: In this work, we proposed a high-resolution D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor based on gold grating. Gold grating is introduced to modulate the resonance wavelength and enhance the refractive index (RI) sensitivity. Structure parameters of PCF and gold grating are analyzed by the finite element method for optimizing the SPR sensor. The simulation results indicate that air hole pitch, air hole diameter, and gold thickness and grating constant have little influence on the sensitivity of the refractive index, which reduces the requirement of precise processing. For improving the resolution of RI sensing, a two-feature (2F) interrogation method, which combines wavelength interrogation and amplitude interrogation, is used. The maximum theoretical resolution of the SPR sensor reaches to 5.98×10-6 RIU in the range of 1.36-1.38, and the wavelength sensitivity reaches to 3340 nm/RIU. The proposed SPR sensor shows potential applications for developing a high-sensitivity, real-time, and fast-response SPR-RI sensor.

Terahertz Sensing in a Hollow Core Photonic Crystal Fiber

Abstract: A terahertz sensor based on a hollow core photonic crystal fiber has been proposed in this paper for chemical analyte detection in the terahertz frequency range. The Zeonex-based asymmetrical hollow core is filled with an analyte and surrounded by a number of asymmetrical rectangular air holes bounded by a perfectly matched layer with absorbing boundary conditions. The performance of the proposed sensor is numerically investigated by using finite element method-based COMSOL software. It is found that a hollow core provides a high relative sensitivity as well as low transmission loss. Moreover, simplicity in design facilitates manufacturability, making it practical for a number of different biological and industrial applications.

Gold-coated photonic crystal fiber biosensor based on surface plasmon resonance: Design and analysis

Abstract: The particularly sensitive circular lattice Photonic Crystal Fiber (PCF) based Surface Plasmon Resonance (SPR) sensor is proposed to gain high sensitivity for the detection of unknown analytes. In this model, two-layer PCF based on the SPR has been designed. A plasmonic chemically inactive material gold (Au) with thickness 35 nm is used to the outside of the PCF structure which exhibits negative real permittivity. A circular perfectly match layer (PML) outside the structure is applied to evaluate the performance of the sensor. The raised design has consisted of symmetric air-hole. Three small air-holes are used in second layer and center which help us to produce more evanescent field. Using the wavelength interrogation method the proposed model shows the maximum wavelength sensitivity of 9000 nm/RIU (Refractive Index Unit) and using the amplitude interrogation method it shows the maximum amplitude sensitivity of 318 RIU−1 with maximum sensor resolution 1.11 × 10−5 in the sensing range among analyte 1.34–1.37. Here the proposed model is investigated how phase matching points are varied with changing parameters as like diameter, PML, thickness of gold (Au), sensing layer and pitch. The obtained result reveals that the proposed model may be used in biochemical and biological analyte detection to find out the important application.

Broadband ultra-flattened dispersion, ultra-low confinement loss and large effective mode area in an octagonal photonic quasi-crystal fiber.

Abstract: In this work, an octagonal Penrose-type photonic quasi-crystal fiber (PQF) with dual-cladding is proposed. By optimizing three geometric degrees of freedom, the PQF exhibits ultra-flattened near-zero dispersion of 0.014±0.293 ps/nm/km, ultra-low order confinement loss of 10−4 dB/km, and large effective mode area of over 16.2 μm2 in a broadband of wavelength from 1.27 to 1.67 μm, covering almost all optical communication bands. At the common communication wavelength 1.55 μm, completely opposite trends of the dispersion and the confinement loss varying with the air-filling factor in the inner cladding are demonstrated. In addition, the robustness of optical properties including dispersion, confinement loss, and effective mode area in this PQF is discussed, assuming a deviation ±3% of all air holes.

Highly sensitive surface plasmon resonance biosensor based on a low-index polymer optical fiber

Abstract: A highly sensitive refractive index sensor based on surface plasmon resonance in a side-polished low-index polymer optical fiber is proposed for biosensing. Benefitting from the low refractive index of the fiber core, the sensitivity of the device can reach ~44567 nm/RIU theoretically for aqueous solutions, at the expense of a lowered upper detection limit that is down to ~1.340. The sensor is fabricated by coating 55-nm-thick Au-film on the polished surface of a graded-index perfluorinated polymer optical fiber. Results show that the sensor exhibits a sensitivity of ~22779 nm/RIU at 1.335 with a figure of merit of 61.2. When employed for glucose sensing, the sensor presents an averaged sensitivity of 24.50 nm/wt%, or 0.46 nm/mM. This device is expected to have potential applications in cost-effective bio- and chemical-sensing.

Salinity sensor using photonic crystal fiber

Abstract: A salinity sensor employing photonic crystal fiber is designed for measuring the concentration of salt in sea water. The sea water sample is infiltrated into one of the air holes in cladding, which offers high confinement loss and act as an analyte core mode and background acts as silica mode. In order to satisfy the phase matching condition, the power transferred from silica core to the liquid filled analyte core, which is investigated using finite element method. An enhanced sensitivity of salinity in sea water reports as 5405 nm/RIU for x -polarization and 5675 nm/RIU for y -polarization with a detection limit of 0.0037 RIU has been reported. The proposed PCF also promises to yield the large birefringence of order 10 −3 along with the enhanced sensitivity.

Twin Core Photonic Crystal Fiber Plasmonic Refractive Index Sensor

Abstract: This paper presents a highly sensitive plasmonic refractive index (RI) sensor on a dual-core photonic crystal fiber (PCF). The performance of the RI sensor is weighed in terms of amplitude sensitivity, wavelength sensitivity, wavelength resolution, and linearity of the resonance wavelength. Numerical result shows that the maximum amplitude sensitivity of 725.8918 RIU $^{-1}$ and 1085 RIU $^{-1}$ are achieved for $x$ - and $y$ -polarization, respectively, by using amplitude interrogation method. In addition, the wavelength interrogation method gives the maximum wavelength sensitivity of around 9000 nm/RIU for both $x$ - and $y$ -polarized modes. Moreover, the maximum wavelength resolution of $1.11\times 10^{-5}$ RIU and the value of the co-efficient of determination ( $\text{R}^{2}$ ) of 0.9784 are reported. The proposed high-performance plasmonic RI sensor can be a favorable candidate for the detection of biological and biochemical analytes.

Surface Plasmon Resonance Sensor Based on Modified $D$ -Shaped Photonic Crystal Fiber for Wider Range of Refractive Index Detection

Abstract: A wider range of refractive index (RI) detecting $D$ -shaped photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is proposed in this paper for the RI detection of analyte ranging from 1.18 to 1.36. To make the proposed sensor practically implementable, analyte sensing layer and chemically stable gold (Au) as a plasmonic material layer for SPR are placed outside the $D$ -shaped PCF structure as a part of simple detection technique. Using the finite-element method with a circular perfectly matched boundary layer, it is shown through simulations that the proposed $D$ -shaped PCF-based SPR sensor offers maximum wavelength interrogation sensitivity of 20 000 nm/RIU (refractive index unit) and maximum amplitude interrogation sensitivity of 1054 RIU−1. In addition, the proposed sensor shows maximum wavelength interrogation resolutions of $5\times 10^{-6}$ RIU and amplitude interrogation resolutions of $16.7\times 10^{-6}$ RIU. Due to high wavelength and amplitude sensitivity over wider range of analyte RI and improved sensing resolutions, this proposed sensor can be implemented for the detection of biological analytes, organic chemicals, bio-molecules, and other analytes.

Plasmonic Refractive Index Sensor Employing Niobium Nanofilm on Photonic Crystal Fiber

Abstract: This letter presents a numerical investigation of a highly sensitive refractive index sensor based on surface plasmon resonance. An ultrathin niobium nanofilm is proposed as a new plasmonic material, which outperforms existing plasmonic materials. This nanofilm is employed on a photonic crystal fiber for the first time resulting sensing over a wide range of refractive indices. Finite-element method-based numerical analysis shows that maximum amplitude sensitivity of 1560 RIU $^{-1}$ and wavelength sensitivity of 8000 nm/RIU can be obtained for an analyte index of 1.40. A thin aluminum oxide (Al2O3) film is deposited on the outer layer of niobium film to enhance the coupling strength and in order to tune the resonance wavelength. Moreover, the effects of varying thickness of niobium nanofilm and Al2O3 film on sensing performance are also discussed. The proposed niobium nanofilm based sensor can be potentially implemented in biochemical and organic chemical sensing.

Ultra-highly sensitive gas pressure sensor based on dual side-hole fiber interferometers with Vernier effect.

Abstract: We have presented and demonstrated a fiber optic gas pressure sensor with ultra-high sensitivity based on Vernier effect. The sensor is composed of two integrated parallel Mach-Zehnder interferometers (MZIs) which are fabricated by fusion splicing a short section of dual side-hole fiber (DSHF) in between two short pieces of multimode fibers (MMFs). Femtosecond laser is applied for cutting off part of the MMF and drilling openings on one air hole of the DSHF to achieve magnified gas pressure measurement by Vernier effect. Experimental results show that the gas pressure sensitivity can be enhanced to about −60 nm/MPa in the range of 0-0.8 MPa. In addition, the structure possesses a low temperature cross-sensitivity of about 0.55 KPa/°C. This presented sensor has practically value in gas pressure detection, environmental monitoring and other industrial applications.

Design of human blood sensor using symmetric dual core photonic crystal fiber

Abstract: In this research paper, human blood sensor based on dual core symmetric photonic crystal fiber (DC-S-PCF) is proposed. It is possible by infiltrating blood samples in the provided elliptical hole of the structure. As this structure exerts the different polarization and based on the coupling principle, the sensitivity of the design is achieved. As a result, it gives 13.5 nm/g/dL for the X-polarized mode and 5.96 nm/g/dL for the Y-polarized mode at 5 cm fiber length of the proposed sensor.

AZO Coated Microchannel Incorporated PCF-Based SPR Sensor: A Numerical Analysis

Abstract: An aluminum-doped zinc oxide (AZO) coated photonic crystal fiber (PCF) is proposed and numerically analyzed for surface plasmon resonance-based refractive index (RI) sensing. A microchannel is incorporated in this PCF, which is proposed to be fabricated using a pulsed laser. Such a structure is expected to have less roughness compared to that fabricated by mechanical polishing. Furthermore, properties such as no island formation and absence of intraband transition are added advantages of AZO. Numerical simulation shows that the maximum wavelength sensitivity and the corresponding resolution of this sensor are 5000 nm/RIU and 2 × 10 -5 RIU, respectively. Furthermore, the amplitude sensitivity is found to be as high as 167 RIU -1 . The proposed structure can be easily fabricated and utilized for sensing applications as it does not require either coating of metals on the inner surface of holes of PCF nor filling of the voids of PCF and it requires a small amount of analyte for RI monitoring.

Ultrahigh sensitivity refractive index sensor of a D-shaped PCF based on surface plasmon resonance.

Abstract: We propose a D-shaped photonic crystal fiber (PCF) refractive index sensor with ultrahigh sensitivity and a wide detection range. The gold layer is deposited on the polished surface, avoiding filling or coating inside the air holes of the PCF. The influences of the gold layer thickness and the diameter of the larger air holes are investigated. The sensing characteristics of the proposed sensor are analyzed by the finite element method. The maximum sensitivity can reach 31,000 nm/RIU, and the refractive index detection range is from 1.32 to 1.40. Our proposed PCF has excellent sensing characteristics and is competitive in sensing devices.

Highly amplitude-sensitive photonic-crystal-fiber-based plasmonic sensor

Abstract: Simple structure, quick response, and highly sensitive miniaturized sensors are highly desirable for the broad range of sensing applications. In this work, we numerically investigated a highly sensitive photonic-crystal-fiber (PCF)-based plasmonic sensor for refractive index sensing. We consider gold as the plasmonic material, which is used outside the fiber structure to exhibit the plasmonic phenomena and to help detect the surrounding medium refractive index. The proposed PCF is designed to enable the evanescent field to interact with an external sensing medium leading to a highly sensitive response. The sensor performance has been investigated by wavelength and amplitude interrogation methods. The proposed sensor exhibits the maximum amplitude sensitivity of 2,843 RIU−1 with the sensor resolution of 3.5×10−6 RIU, which is the highest among the reported PCF SPR sensors, to the best of our knowledge. It also shows wavelength sensitivity of 18,000 nm/RIU and sensor resolution of 5.6×10−6 RIU. The figure of merit of the proposed sensor is about 400. The sensor response also allows us to detect the refractive index variation in the range of 1.33 to 1.41. Such promising results and broad sensing range ensure that the proposed sensor will be a suitable candidate for biological analytes and biochemical and organic chemical detections.

Effect of anti-crossings with cladding resonances on ultrafast nonlinear dynamics in gas-filled photonic crystal fibers

Abstract: Spectral anti-crossings between the fundamental guided mode and core-wall resonances alter the dispersion in hollow-core anti-resonant-reflection photonic crystal fibers. Here we study the effect of this dispersion change on the nonlinear propagation and dynamics of ultrashort pulses. We find that it causes emission of narrow spectral peaks through a combination of four-wave mixing and dispersive wave emission. We further investigate the influence of the anti-crossings on nonlinear pulse propagation and show that their impact can be minimized by adjusting the core-wall thickness in such a way that the anti-crossings lie spectrally distant from the pump wavelength.