Sensitive DNA biosensor based on a long-period grating formed on the side-polished fiber surface.

We demonstrate a sensitive DNA biosensor based on a long period grating (LPG) formed by a photolithograph process on the surface of a side-polished fiber. The biomolecules of the biosensor were immobilized on the silica surface between LPG patterns. The resonance wavelength was red-shifted after the binding of the poly-L-lysine, probe ssDNA and target ssDNA to the sensor surface.

Meshed index profile method for photonic crystal fibers with arbitrary structures.

A meshed index profile method, which is based on the localized function method, is demonstrated for analyzing modal characteristics of photonic crystal fibers with arbitrary air-hole structures. The index profile of PCF, which is expressed as a sum of meshed unit matrix, is substituted to full wave equation. By solving this full wave equation, we obtain the modal characteristics of the PCF such as the mode field distribution, the birefringence and the waveguide dispersion.

Characterization of tunable photonic crystal fiber directional couplers.

We present a tunable photonic crystal fiber (PCF) directional coupler fabricated by a side-polishing method. The PCF directional coupler was modeled as a typical single-mode fiber-based directional coupler and analyzed using the improved effective-index method (IEIM). The characteristics of the PCF directional coupler such as the coupling coefficient and the coupling ratio were measured and found to be in good agreement with those predicted by the theoretical model.