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A three-core photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) has been designed with silver film coated on the inner wall of a microfluidic detection channel with three V-grooves. The coupling characteristics and sensing properties of the proposed sensor are analyzed numerically using the full vector finite element method (FEM). The loss spectra and the sensing performance are found to be effectively tuned by the structure parameters of the plasmonic sensor. The simulation results show that an average wavelength sensitivity (WS) of 5413.3 nm/RIU is reached when the refractive index (RI) of the analyte lies in the range from 1.330 to 1.370, while the maximum WS achieves is 11400 nm/RIU, which occurs when the RI varies between 1.365 and 1.370, corresponding to a maximum RI resolution of 8.77 × 10–6 RIU. This is thus extremely sensitive to changes in analyte RI in the microfluidic channel. [ABSTRACT FROM AUTHOR]

A dual-core photonic crystal fiber (PCF) with dual-channel-based surface plasmon resonance (SPR) sensor is designed. The silver and gold films are severally coated in the inner walls of two large ring detection channels to excite the plasmon modes, which can make the designed sensor achieve the dual-channel sensing. The effect of structure parameters on the sensing properties and loss spectrum is numerically analyzed by finite element method (FEM). When the analyte refractive index (RI) changes from 1.340 to 1.360, the average spectral sensitivities of 4280 and 3940 nm/RIU are obtained for the left and right channels, corresponding to the RI resolutions of 2.34 × 10−5 and 2.54 × 10−5 RIU, respectively. The simulation results suggest that the designed dual-channel sensor can realize highly sensitive detection of two analytes simultaneously, which has a wide application in the fields of biomedical analysis and environmental monitoring. [ABSTRACT FROM AUTHOR]

A D-shaped photonic crystal fiber surface plasmon resonance (PCF-SPR) sensor is proposed for highly sensitive liquid refractive index sensing. Taking sensing sensitivity into consideration, silver-titanium dioxide (Ag-TiO2) composite micro-grating is introduced and SPR is excited within Ag-TiO2 composite micro-grating at the flat D-shaped PCF surface. The finite element method (FEM) based on COMSOL is applied to analyzed numerically response characteristics of the D-shaped sensor, which was research dependent on wavelength and amplitude interrogation method. The results displayed that designed sensor reached excellent amplitude sensitivity of 2245 RIU−1 and wavelength sensitivity of 10,300 nm/RIU for liquid refractive index varying between 1.33 and 1.40. And it also shows that the maximum figure of merit was 480 RIU−1 for proposed sensor after optimization of structural parameters, which has a great prospect in the biological detection and chemical analysis. [ABSTRACT FROM AUTHOR]

A dual-core photonic crystal fiber (PCF) based on surface plasmon resonance (SPR) sensor with segmented silver film (silver nanoslit) deposited in microfluidic channel is designed. The coupling characteristics and sensing performance of the proposed sensor are analyzed numerically by finite element method (FEM). The resonance intensity and wavelength sensitivity can be tuned by the segmented number and angle of the silver nanoslit, due to a strong coupling between propagation surface plasmon resonance (PSPR) on the silver film surface and local surface plasmon resonance (LSPR) at the silver nanoslit. When the segmented number is 40 and the segmented angle is 0.5°, an average sensitivity of 5100 nm/RIU is obtained in the refractive index (RI) range from 1.330 to 1.360, and is 1080 nm/RIU higher than that of continuous silver film structure under the same conditions. In addition, a maximum wavelength sensitivity of 7600 nm/RIU is achieved in the RI range from 1.355 to 1.360, corresponding to a high RI resolution of 1.32 × 10−5 RIU, which can be used to detect the slight change in the RI of an unknown analyte. [ABSTRACT FROM AUTHOR]

The research of polarization-maintaining photonic crystal fiber with temperature insensitive characteristic is one of the important methods to solve the temperature dependence problem in the engineering application of an optical sensing system. This paper presents a new kind pentagonal polarization-maintaining photonic crystal fiber, and its polarization characteristic under the influence of temperature was analyzed based on the theory of the thermal expansion effect and thermal optic effect. The results show that the temperature dependence of the proposed fiber is significantly lower than that of the hexagonal photonic crystal fiber with the same design parameters at -50℃˜80℃. It has potential application value in some optic fiber sensing systems that need high precision and working stability under the turbulence of temperatures, such as fiber optical voltage sensor, fiber optical current sensor and fiber optic gyroscope. [ABSTRACT FROM AUTHOR]

In this paper, polarization-maintaining photonic crystal fibers (PM-PCFs) with odd-edge and even-edge arrangements of air holes in cladding, such as pentagon, hexagon, heptagon, and octagon, were taken as the research objects. The temperature characteristics of birefringence and loss of fibers with different structures in the bending state were compared and analyzed. The results show that the PM-PCFs with the cladding air holes odd-edge distributed have better thermal stability, especially the fiber with the pentagonal distribution of cladding air holes. This research provides a theoretical reference for selecting optical fibers and designing methods for photonic crystal fiber applications that require high output performance stability [ABSTRACT FROM AUTHOR]

• A nonreciprocal error model of the RAOVS was established. • A significant idea was proposed to suppress nonreciprocal error. In the reflected all-optical voltage sensor (RAOVS) based on the converse piezoelectric effect, the influence of ambient temperature on the system output cannot be ignored when the length of sensing fiber and compensating fiber is asymmetric. In this study, the nonreciprocal error model of the RAOVS due to the asymmetric fiber length is originally established, according to the polarization optics theory. Then, the influence of temperature fluctuation and asymmetric fiber length on the output error is investigated with the condition of different voltage levels. Finally, a method for suppressing the nonreciprocal error is presented from the sensing fiber performance. Results show that the increase of nonreciprocal phase shift is proportional to the asymmetric fiber length and it is hardly avoided in the assembly process. And the magnitude of nonreciprocal error is influenced by ambient temperature fluctuation. Interestingly, the nonreciprocal error can be reduced by ~75 times with employing polarization-maintaining photonic crystal fiber (PM-PCF) as sensing fiber. This study can provide a theoretical basis for suppressing the nonreciprocal phase shift error of RAOVS in practically. [ABSTRACT FROM AUTHOR]

The temperature dependence of polarization-maintaining (PM) property and loss in a highly-birefringent air-core photonic band-gap fiber (PBF) is investigated. The effects of temperature variation on the effective index, beat-length and confinement loss are studied numerically by using the full-vector finite element method (FEM). It is found that, the PM property of this PBF is insensitive to the temperature, and the temperature-dependent beat-length coefficient can be as low as 2.86×10 −8 m/°C, which is typically 200 times less than those of conventional panda fibers, the PBF has a stable confinement loss of 0.01 dB/m over the temperature range of −30 to 20 °C for the slow axis at the wavelength of 1.55 μm. The PBF with ultra-low temperature-dependent PM property and low loss can reduce the thermally induced polarization instability apparently in interferometric applications such as resonant fiber optic gyroscope (RFOG), optical fiber sensors, and so on. [ABSTRACT FROM AUTHOR]