Crystal Refractive Index Research Articles

Simulation analysis of a photonic crystal fiber refractive index sensor based on a double-layer film structure and surface plasmon resonance technology

A photonic crystal fiber surface plasmon resonance sensor based on a double-layer membrane structure is designed and analyzed. In the simple sensing structure with only one air hole size, TiO2 and Au layers with specific thicknesses are sequentially coated on the optical fiber to form a double-layer structure. The sensing characteristics of the double-layer membrane structure are studied by the finite element method. Compared to the single-layer membrane structure, the double-layer membrane sensor has significant sensing properties such as a better wavelength sensitivity and a smaller full width at half maximum in the loss spectrum. In the refractive index range between 1.37 and 1.43, the maximum wavelength sensitivity and average wavelength sensitivity of the sensor are 19,900 nm/RIU and 7417 nm/RIU, respectively, and the resolution can be up to 5.03×10−6RIU. The proposed photonic crystal fiber optic sensor achieves high performance with a simpler sensing structure than previous photonic crystal fiber optic sensors, and eliminates the step of polishing, which will greatly reduce the difficulty of actual fabrication and the error due to uneven polishing. The results show that the photonic crystal fiber optic sensor with a double-layer membrane structure has excellent performance. Due to its high sensitivity and resolution, it has great potential for applications in environmental monitoring, biosensing and chemical sensing.

Gold-coated D-shaped photonic crystal fiber refractive index sensor with a wide detection range and large manufacturing tolerance

A D-shaped photonic crystal fiber refractive index (RI) sensor is designed, and its performance is analyzed using the finite element method (FEM). A gold film is coated on the D-shaped surface of the fiber as a plasmonic material for surface plasmon resonance sensing. The U-shaped arrangement of holes of the same size in the fiber structure enhances the coupling resonance between the core mode and the surface plasmon polariton mode. Numerical results show that the RI range of the sensor is 1.20–1.40, the maximum wavelength sensitivity is 16008.98 nm/RIU, and the detection width is up to 0.2 RIU. In addition, this study analyzes the manufacturing tolerance for the sizes of the air holes. The results show that the manufacturing tolerance for the three types of air holes is as high as 25%, 11.1%, and 10.2% when h is 40µm. These findings lay the foundation for the mass production of sensors. The above results indicate that the sensor has remarkable advantages such as enhanced sensitivity, wide measurement range, and exceptional manufacturing stability, and has promising applications in the fields of bio-detection, drug supply detection, and water pollution control.

A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance effect

A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance effect

D-type photonic crystal fiber refractive index sensor based on Bloch surface waves

Bioassays are important in health assessment, disease diagnosis, treatment monitoring, disease prevention, and environmental monitoring to provide better health management and quality of life for individuals and society. A D-type photonic crystal fiber optic sensor based on Bloch surface waves is proposed for biological detection within an ultra-wide refractive index. The designed D-type fiber was side-polished and alternately deposited with one-dimensional photonic crystals (1DPCs) on the polished side, consisting of a set of TiO2 and SiO2 alternating media with moderate refractive index differences. The designed PCF consists of symmetric air holes and polished structures. The structural parameters of this sensor are also analyzed and discussed in order to obtain better detection performance. The designed Bloch surface wave D-type photonic crystal fiber optic sensor has a maximum refractive index sensitivity of 5400 nm/RIU and a maximum amplitude sensitivity of 513.00RIU−1. The sensor also has a resolution of 1.85×10−5RIU and an excellent maximum quality factor (FOM) of 222.43RIU−1. These results show a higher figure of merit (FOM) than conventional methods, resulting in increased sensitivity and accuracy. The proposed sensor can detect the RI of unspecified analytes between 1.20 and 1.50, allowing for the analysis of many different types of analytes, such as viruses, blood plasma, cancer cells, sugars, proteins, DNA/RNA, and many more.

Simultaneous measurement of thickness and group refractive index in birefringent crystals

In order to measure the group refractive index and thickness of birefringent crystals simultaneously, a method based on spectral-domain interferometry is proposed. The optical path of each reflection layer of birefringent crystal is converted into spectral interference fringe of corresponding frequency by the principle of spectral-domain interferometry, and the accurate optical path calculation is realized by fast Fourier transform and Hanning-windowed energy centrobaric method. A two-step measurement method was designed to measure the crystal thickness and group refractive index of ordinary ( o ) and extraordinary ( e ) light synchronously by comparing the changes of the optical path before and after the insertion of the sample. The comparison between experimental and theoretical results of LiNbO3 crystals shows that the accuracy of the thickness measured by this system is better than 1 μm and the relative error of the group refractive index is better than 0.15%. The measurement method is simple to implement and has high precision, which is of practical significance for realizing the rapid and high-precision measurement of optical parameters of birefringent crystals.

D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

D-type photonic crystal fiber low refractive index sensor based on surface plasmon

This study presents the design and analysis of a novel surface plasmon resonance sensor based on D-type photonic crystal fiber. The analyte channel in the sensor comprises an open ring with a thin gold film deposited on the channel, inducing the surface plasmon resonance effect to enhance the resonance effect and improve the spectral sensitivity of the sensor. The proposed design eliminates the need to introduce liquid into the analyte channel. Upon inserting the sensor into the vessel, the analyte automatically flows into the liquid channel. Simulations illustrate the capability of the proposed sensor to detect low refractive indices spanning from [Formula: see text] to [Formula: see text], exhibiting a remarkable spectral sensitivity of up to 9000[Formula: see text]nm/RIU. The surface plasmon resonance sensor presented in this study emerges as a competitive candidate for applications requiring low refractive index detection. It is all because of its promising sensing results, wide refractive index sensing range, and simple, compact fiber design.

Fabrication and Characterization of Colorant-Doped Glass Produced with Local Sand of Nong Phok Site

It is well-known that silica sand is a special type of quartz sand that is suitable for glass fabrication due to its high silica content and low content of iron oxide. In this work, chemical analysis has been carried out on a sand sample from the Nong Phok site, Roi Et province, northeastern Thailand. The geological resources show that this site possesses a surface-to-near surface sand deposit. The grain of fine white sand consists of clear crystals. The grain shape is mainly angular-to-round. Chemical analysis shows that the sand contains more than 99 wt% silica and small amounts of Al, Ca, Ti, and Zr which is in agreement with international standards for glass production. The sand has been used as raw material for the fabrication of soda-lime, lead crystal, and lead-free high refractive index glasses. The colorless and various colored glass products have been satisfactorily used in domestic art and glass manufacturers which promotes local employment and economics.

Enhanced optical contrast of Ag-doped Ge-Sb-Se-Te phase change films

The phase change material (PCM) Ge2Sb2Se4Te1 film doped by Ag (AGSST) was prepared by the pulsed laser deposition (PLD) method. The crystal structure, chemical bonding and film complex refractive index were investigated. The AGSST undergoes a phase transition through annealing. The extinction coefficient of crystalline (CR) AGSST has been significantly lowered for the communication C-band at 1550 nm, with a figure of merit (FOM) of 7.48, surpassing that of undoped GSST. This outcome delivers chalcogenide PCMs that are potentially in the development of programmable nonvolatile photonics.

High sensitivity photonic crystal fiber temperature and refractive index sensor based on surface plasmon resonance

High sensitivity photonic crystal fiber temperature and refractive index sensor based on surface plasmon resonance

Design and numerical investigation of a dual-core photonic crystal fiber refractive index sensor for cancer cells detection

Design and numerical investigation of a dual-core photonic crystal fiber refractive index sensor for cancer cells detection

Photonic crystal fiber refractive index sensor based on SPR

Photonic crystal fiber refractive index sensor based on SPR

Mid-infrared refractive index photonic crystal fiber sensor based on surface plasmon resonance for ultra-high sensitivity

An ultra-high sensitivity photonic crystal fiber mid-infrared refractive index (RI) sensor based on surface plasmon resonance is proposed, whose properties are investigated by the finite element method. Gold can be utilized to create excitation between the fundamental mode and surface plasmon polaritons mode. The simulation results indicate that, at the wavelength of 1.7–4.0 μm, the proposed sensor could detect a RI in the range of 1.00–1.31, a maximum sensitivity of 37 000 nm RIU−1, and an optimal resolution of 2.70 × 10−6 RIU is achieved. The result of curve fitting is 0.98185. The proposed mid-infrared RI sensor plays an important role in organic chemistry detection, medical detection, and related fields.

Double-layered side-polished ultra-highly sensitive photonic crystal fiber-based surface plasmonic refractive index sensor

Double-layered side-polished ultra-highly sensitive photonic crystal fiber-based surface plasmonic refractive index sensor

Consequence of Fibonacci quasiperiodic sequences in 1-D photonic crystal refractive index sensor for the blood plasma and cancer cells detections

We present the consequences of different Fibonacci quasiperiodic sequences on the sensing performance of a one-dimensional (1D) photonic crystal (PC) based sensor to detect the blood plasma and cancer cells. We demonstrate that the sensitivity and figure of merit (FOM) of the sensor can be modulated, respectively, from 427.5 nm/RIU to 530 nm/RIU and from 162.5 RIU−1 to 2983.33 RIU−1 by utilizing the pertinent sensor structures with Fibonacci generation and structural parameters for the analyte refractive index from 1.31 to 1.41. We have also shown that the operational sensing wavelengths and sensitivity can be changed significantly by introducing the different Fibonacci sequences in the proposed sensor. The sensing peaks separation, FWHM, and sensitivity can also be tuned by changing the analyte and PC stacked layers' thicknesses. We also introduce the sensing performances for the Blood plasma and Cancer cells detection using the proposed Fibonacci quasiperiodic PC sensor. We observe that the maximum sensitivities and FOM of the proposed sensor are 552.5 nm/RIU and 2986.93 RIU−1 for cancer cells and 553.55 nm/RIU and 2214.21 RIU−1 for blood plasma, respectively. The proposed structure reveals the tunable sensing performances and stimulates the fabrication interest.

Sagnac ring and photonic crystal fiber structure refractive index sensor with high birefringence and low temperature sensitivity

In this paper, a novel refractive index sensor based on photonic crystal fiber and Sagnac ring is studied. The sensor adopts Mach-Zehnder interference principle. The production and experimental steps are as follows: The first step is to fuse the single-mode fiber with the photonic crystal fiber to form a basic sensing unit. The second part uses the coupling birefringence effect of the tapered coupler to fold and fuse the single-mode fiber together to form the Sagnac interferometer. Through this structure, the sensor has the characteristics similar to the polished photonic crystal fiber sensor, while the fabrication complexity is greatly reduced. The refractive index sensing capability and temperature stability of the two structures are analyzed experimentally. Simulation results show that the structure has high birefringence effect. Experimental results show that the proposed photonic crystal fiber combined with Sagnac ring sensor has good sensing performance in the refractive index range of 1.3355–1.3560. Compared with the sensor structure without Sagnac ring, the performance is greatly improved, the maximum sensitivity is up to 234 nm/RIU, and it has good temperature stability. The sensor has the advantages of miniaturization, high integration and high sensitivity, and can be used in industry, chemical detection, agriculture and other fields.

Highly sensitive refractive index sensor based on photonic crystal ring resonators nested in a Mach–Zehnder interferometer

Today, with the rapid development of photonics, optical sensors are being considered as efficient tools for detecting environmental variations and have been regarded as one of the most important fields in photonic research. In this study, we have proposed a two-dimensional photonic crystal refractive index sensor using a combination of Mach–Zehnder interferometers and two ring resonators. Our goal is to increase the sensitivity and figure of merit of the sensor, so that the output transmission spectrum can be considerably shifted by changing the refractive index of the simulated analytes. The proposed photonic crystal sensor consists of a hexagonal array of silicon rods on a SiO2 substrate. The finite difference time domain method is used for the numerical simulation of the structure. In this regard, to validate the simulation results, two different commercial software have been used. The quality-factor and the sensitivity of the proposed structure are 1535 and 1658 nm/RIU, respectively, where RIU stands for the refractive index unit. In general, the structure has advantages such as low fabrication cost, high sensitivity to changes in refractive index and a high Q-factor.

Photonic crystal fiber refractive index temperature sensor based on double spherical cascade

A dual spherical photonic crystal fiber (PCF) Mach-Zender refractive index temperature sensor is proposed. The sensing structure is a PCF fused to a spherical structure made of two single-mode fibers, of which the two spherical structures serve as beam splitter and coupler, respectively, for refractive index sensing experiments. In addition, temperature sensing experiments were conducted by filling the middle PCF with ethanol using the same structure. Experimental results show a maximum sensitivity of 190.26 nm/RIU for the wavelength drift of the resonance valley of the interference spectrum in the refractive index range of 1.348–1.358. The maximum sensitivity of the wavelength drift of the resonant valley of the interference spectrum is − 0.306 nm/°C for temperatures in the range of 40–50 °C. The sensor studied in this paper is characterized by high sensitivity, simple manufacturing, and low cost.

Design and analysis of surface plasmon resonance sensor based on multi-core photonic crystal fiber

A three-core photonic crystal fiber refractive index sensor based on the surface plasmon resonance effect is proposed. The three cores of this sensor are symmetrical about the center. The gold film deposited outside the fiber structure makes this sensor contact with the analyte directly, which not only reduces the complexity of the fabrication but also makes the limiting loss very low. The sensing performance of the proposed sensor is investigated by using the finite element method. Numerical results show that the loss spectra of the x-polarized core mode are consistent with the y-polarized core mode. The sensor realizes the sensing detection of the analyte refractive index ranging from 1.37 to 1.42. When the analyte’s refractive index is 1.42, the maximum wavelength sensitivity of 2427 nm/RIU for x and y polarization, the corresponding maximum resolution can reach 4.12 × 10−5 RIU.

Propagation of sine beam in uniaxial crystal orthogonal to optical axis

AbstractThis study analyzes propagation properties of sine beam in uniaxial crystal orthogonal to optical axis. Huygens‐Fresnel integral is solved to find the received field. Influence of source beam parameters, crystal refractive index settings, and propagation distance is analyzed in detail. Our results yield that intensity concentrates on minimum and maximum of x‐axis at middle and longer propagation distances. Although, sinusoidal waveform is conserved at close distance. We hope that these results will be used in optical tracking applications.