Guowen An

Extra-broad Photonic Crystal Fiber Refractive Index Sensor Based on Surface Plasmon Resonance

We propose and investigate a photonic crystal fiber (PCF) refractive index sensor with triangular lattice and four large-size channels based on surface plasmon resonance. In such sensor, two gold wires obtained by chemical reaction are filled in two air holes between the upper and lower channels. Numerical results show that the refractive indexes of the analytes can be detected from 1.30 to 1.79. It’s a very broad detection range that is rarely seen in the field of photonic crystal fiber sensor based on surface plasmon resonance. The average sensitivity of this photonic crystal fiber could be 100 nm/refractive index unit (RIU) in the dynamic index range from 1.30 to 1.63. In the range from 1.63 to 1.79, the highest sensitivity could reach to 3233 nm/RIU. The ability to integrate four large-size microfluidic channels for efficient analyte flow in is attractive for the development of integrated highly sensitive PCF-SPR sensors.

High-birefringence photonic crystal fiber polarization filter based on surface plasmon resonance.

In this paper, we designed a C2v-symmetry-structured photonic crystal fiber with triangular lattice and Au-filled air holes. The finite element method is used to analyze the dispersion and confinement loss characteristics of the core mode and the surface plasmon mode of the metal wire. In this work, we found that the positions of resonance peaks and the resonance strength of core mode and surface plasmon mode can be well adjusted by changing the pitch between the cladding air holes and the diameters of the air holes or metal wires around the core. By optimizing the parameters of the fiber structure, a polarization filter at the communication band is designed. At the wavelength of 1.31 μm, which is located in the communication band, the fundamental mode in X pol can be filtered with the diameter of the metal wire d(m)=1.2  μm. When d(m)=1.4  μm, the fundamental mode in Y pol can be filtered at the wavelength of 1.55 μm, which is also located in the communication band. Compared with the ordinary single-polarization and single-mode photonic crystal fiber, the fiber we proposed in this paper can selectively filter out the polarized light in one direction by adjusting the wire diameter. It is meaningful for the development of the polarization filter in the communication band.

High-sensitivity and tunable refractive index sensor based on dual-core photonic crystal fiber

A novel refractive index sensor based on dual-core photonic crystal fiber with a rectangular lattice has been proposed. The two cores of the fiber are separated by one air hole filled with analytes whose refractive indices range from 1.33 to 1.41. Numerical simulation results show that the highest sensitivity can reach 14,216 nm/RIU (refractive index unit) when the refractive index of the analyte is 1.41, and even the lowest sensitivity can also be achieved at 6787 nm/RIU. The sensor size can be as short as 300–500 μm, which makes the sensor production very cost effective. Applications for the proposed sensor can be found in blood glucose testing instruments or moisture meters and in fields that need highly accurate detection such as water quality analysis, clinical medicine detection, and pharmaceutical testing (liquid medicine).

Photonic crystal fibre polarization filter with round lattice based on surface plasmon resonance

A kind of photonic crystal fibre polarization filter with round lattice based on surface plasmon resonance is proposed. Complete coupling happens between core mode and second-order surface plasmon polariton (SPP) mode when the phase-matching condition is satisfied. We can adjust the resonance point and strength in two polarizations by changing the fibre birefringence and the thickness of gold film. Numerical simulation with the finite-element method shows that the resonance strength can reach 364.8 dB/cm in the y-polarized direction at the communication wavelength of 1550 nm, when the diameter of big air holes that lead to the birefringence is 2.0 m and the thickness of gold film is 26 nm. Moreover, when the fibre length is 800 m, the peak value of the crosstalk can reach 231.8 dB and the bandwidth of the crosstalk better than 20 dB can reach 130 nm. This makes it a promising candidate for polarization filter devices.

High Sensitivity Refractive Index Sensor Based on Dual-Core Photonic Crystal Fiber with Hexagonal Lattice

A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated by two air holes filled with the analyte whose refractive index is in the range of 1.33–1.41. Numerical simulation results show that the highest sensitivity can be up to 22,983 nm/RIU(refractive index unit) when the analyte refractive index is 1.41. The lowest sensitivity can reach to 21,679 nm/RIU when the analyte refractive index is 1.33. The sensor we proposed has significant advantages in the field of biomolecule detection as it provides a wide-range of detection with high sensitivity.

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

A type of D-shaped photonic crystal fiber sensor based on surface plasmon resonance (SPR) is proposed for refractive index sensing and analyzed by the finite element method. The SPR effect between surface plasmon polariton modes and fiber core modes of the designed D-shaped photonic crystal fiber is used to measure the refractive index of the analyte. Numerical results show that the sensor can detect a range of refractive index ranging from 1.33 to 1.38. When the thickness of metal film is t=20  nm, the maximum sensitivity of 10,493  nm/RIU is obtained with a very high resolution of 9.53×10-6  RIU. The good sensing performance makes the proposed sensor a competitive candidate for environmental, biological, and biochemical sensing applications.

Ultra-stable D-shaped Optical Fiber Refractive Index Sensor with Graphene-Gold Deposited Platform

In this paper, we demonstrate a high sensitivity refractive index (RI) sensor with D-shaped structure covered with gold and graphene film. Specifically, the effect of structural parameters on the stability of fiber sensor is analyzed. In our research, it have been found that the sensor we proposed is not very sensitive to the change of structure parameters on the premise of ensuring the sensing precision. This advantage means that the requirements for machining errors are reduced. Further probing shows that the proposed sensor shows a maximum wavelength interrogation sensitivity of 4391nm/RIU with the dynamic refractive index range from 1.33 to 1.39 and a maximum amplitude sensitivity of 1139RIU− 1 with the analyte RI = 1.38 in the visible region. The corresponding resolution are 2.28 × 10− 5 and 8.78 × 10− 6 based on the methods of wavelength interrogation and amplitude-(or phase-) based method. These characteristics of compact sensing architectures, simple to fabricate, and high sensitivity open the possibility of using this type of sensor in biological applications.