Ultrasensitive photonic crystal fiber refractive index sensor

Abstract

We introduce a microfluidic refractive index sensor based on a directional coupler architecture using solid-core photonic crystal fibers. The sensor achieves very high sensitivity by coupling the core mode to a mode in the adjacent fluid-filled waveguide that is beyond modal cutoff, and with strong field overlap. We demonstrate the device through the selective infiltration of a single hole with fluid along a microstructured optical fiber. A detection limit of 4.6x10(-7) refractive index units has been derived from measurements with a sensitivity of 30,100 nm per refractive index unit, which is the highest for a fiber device to date.

Optofluidic refractometer using resonant optical tunneling effect

“…Nowadays, the near-field optics methods, which make use of evanescent waves that exists in the subwavelength region near the interface of two medias, have attracted more and more interests. Inspired by the recent rapid progress of nanotechnology, different near-field mechanisms have been incorporated into the RI measurement, notably surface plasmon resonance ͑SPR͒, [19][20][21] whispering gallery modes of microresonators, 22 photonic bandgap waveguides, 23 photonic crystal fibers, 24 and local coupling of slab waveguides and tapered optical fibers. 25,26 As the near-field effect is confined to a subwavelength region, it intensifies the interaction and thus further improves the sensitivity to a level close to 10 −7 RIU.…”

Bending Analysis of a Dual-Core Photonic Crystal Fiber

“…It is well known that PCFs have shown excellent performances in applications such as optical communications [36][37][38], fiber lasers [39][40][41][42], supercontinuum sources [43][44][45][46] and also fiber sensors [47][48][49][50][51][52][53][54][55][56]. Fiber sensors based on PCFs have shown numerous advantages such as temperature insensitivity for strain sensing [49,50], high sensitivity for gas sensing [51], biochemical sensing [52], refractive index sensing [53] and pressure sensing [54,55], and the flexibility to form fiber sensors based on all-fiber Mach-Zehnder interferometers [56], which are mainly due to the remarkable flexibility in the fiber structure design of the PCF compared with the conventional optical fiber. It is worthy to note that besides the one-core PCF, multi-core PCFs including dual-core PCFs (DC-PCFs) have also been proposed for special applications.…”

Ultrasensitive twin-core photonic bandgap fiber refractive index sensor

“…surface Plasmon resonance (SPR) sensors. The practical detection limit of fiber sensor is bottlenecked by 10 -5 RIU [1,2,3]. Meanwhile, we witness that, due to the flexibility of design and ease of fabrication, multi-core PCFs, especially the multi-core PBGFs, have attracted increasing interests for potential applications of optical communication and sensors [4,5,6].…”