Photonic crystal fiber long-period gratings for biochemical sensing

Abstract

Abstract:We present experimental results showing that long-period gratings in photonic crystal fibers can be used as sensitive biochemical sensors. A layer of biomolecules was immobilized on the sides of the holes of the photonic crystal fiber and by observing the shift in the resonant wavelength of a long-period grating it was possible to measure the thickness of the layer. The long-period gratings were inscribed in a large-mode area silica photonic crystal fiber with a CO 2 laser. The thicknesses of a monolayer of poly-L-lysine and double-stranded DNA was measured using the device. We find that the grating has a sensitivity of approximately 1.4nm/1nm in terms of the shift in resonance wavelength in nm per nm thickness of biomolecule layer.

Review of long period fiber gratings written by CO2 laser

“…7,14 LPFGs can thus be used for biochemical sensing based on the evanescent-wave detection principle. [151][152][153][154][155] As shown in Fig. 21, a promising biochemical sensor based on a LPFG written in a PCF by a CO 2 laser has been demonstrated to detect the average thickness of a layer of biomolecules within a few nm.…”

“…21, a promising biochemical sensor based on a LPFG written in a PCF by a CO 2 laser has been demonstrated to detect the average thickness of a layer of biomolecules within a few nm. 151 Various techniques have been demonstrated to enhance the sensitivities of LPFG-based refractometers 64,65,156 and to solve the cross-sensitivity between temperature and refractive index. 79 A CO 2 -laser-induced LPFG in a microfiber drawn by taping technique has a high sensitivity of about 1900 nm/refractive index ͑RI͒ to external refractive index.…”

Enhancement of Refractive Index Sensitivity in Photonic Crystal Waveguide-Based Sensors by Selective Infiltration

“…Besides, optical sensors eliminate the need for uorescent or radioactive labeling of molecules, which are relatively time-consuming, expensive and large area demanding [1]. Various label-free optical sensing techniques are proposed which are based on surface plasmon resonance [2], interferometry [3 5], waveguides [6,7], optical bers [8] and ring resonators [9 11]. Although, some of these techniques are now mature and even commercialized, these techniques are not very practical for on-chip integration with incorporation of light sources and detectors.…”

Optofluidic waveguides: II. Fabrication and structures

“…Typical diameters of this center core are between 5 and 20 µm. Researchers have demonstrated that the voids of PCFs can be filled with low refractive index fluids that allow for low loss transmission down long lengths of fiber and very long interaction lengths between the light and the fluid Martelli et al 2005;Rindorf et al 2006). Launching light into these fluid filled fibers can be accomplished with the same type of T fixtures used when evaluating glass capillaries (described above).…”