Long-range surface plasmon resonance sensor based on dielectric/silver coated hollow fiber with enhanced figure of merit.

A long-range surface plasmon resonance (LRSPR) sensor based on dielectric/silver-coated hollow fiber (HF) is proposed. It can detect the refractive index (RI) of sensed liquid filled in the hollow core of the sensor. A HF LRSPR sensor with 90-nm-thick silver layer and 260-nm-thick OC300 layer is fabricated. Experiments are taken to evaluate the performance of the sensor by measuring the transmission spectra. Theoretical analysis based on a ray model is also taken, and the results agree well with the experimental results. The proposed sensor has similar sensitivity but much smaller SPR dip width than the silver-coated HF SPR sensor. Thus figure of merit of the sensor is enhanced approximately five times. The stability of the sensor is also improved because the dielectric layer acts as a protection layer for the damageable silver layer.

Hollow fiber surface plasmon resonance sensor for the detection of liquid with high refractive index.

A new kind of surface plasmon resonance (SPR) sensor based on silver-coated hollow fiber (HF) structure for the detection of liquids with high refractive index (RI) is presented. Liquid sensed medium with high RI is filled in the hollow core of the HF and its RI can be detected by measuring the transmission spectra of the HF SPR sensor. The designed sensors with different silver thicknesses are fabricated and the transmission spectra for filled liquids with different RI are measured to investigate the performances of the sensors. Theoretical analysis is also carried out to evaluate the performance. The simulation results agree well with the experimental results. Factors that might affect sensitivity and detection accuracy of the sensor are discussed. The highest sensitivity achieved is 6,607 nm/RIU, which is comparable to the sensitivities of the other reported fiber SPR sensors.

Flexible silver-coated hollow fibers for remote Raman spectroscopic measurements.

A Raman remote spectroscopy system was established by using flexible hollow fibers (HFs) as laser excitation fiber and signal collection fiber. Experimental evaluations with various optical fiber combinations were carried out. Experiments were conducted by using silver-coated HFs as both remote transmission fiber and sample cells for liquid sample detection. Good linearity for concentration detection of liquid was obtained with clean background and signal enhancement. Theoretical analysis was carried out to optimize the length of the liquid cell. Measured data show good agreement with the simulation result. HF has shown potentiality in applications for remote and noninvasive Raman detection.