Experimental study of the copper-coated hollow fiber surface plasmon resonance sensor

A novel optical fiber surface plasmon resonance (SPR) sensor based on the copper-coated hollow fiber structure was proposed. The simple chemical liquid phase deposition method was developed to coat the thin copper film on the inner surface of the hollow fiber to fabricate the proposed sensor. The performance of the hollow fiber SPR sensors with different copper film thickness were investigated experimentally by measuring the transmission spectra of the sensors filled by sensed liquid media with different refractive indices. Theoretical analysis based on the ray transmission model was also carried out for comparison. The experimental and theoretical results agree well with each other. The factors which affect the sensor performance are discussed. The sensor achieves a maximum sensitivity of 7111 nm/RIU, which is relatively high in the copper film based optical fiber SPR sensors and comparable to the silver-coated hollow fiber sensors. Moreover, the fabrication process of the proposed sensor is much simpler than other copper based optical fiber SPR sensors, which make it more practical. The copper film deposition method presented in this paper is also applicable to the fabrication of some microstructured optical fiber or photonic crystal fiber based sensors with copper film.