Fabrication of long-period fiber gratings using end-coupled ultrafast laser pulses.

We propose a novel technique for the fabrication of long-period fiber gratings (LPFGs) using ultrafast laser pulses coupled into opposite ends of an optical fiber. The pulses counter-propagate in the fiber and induce a permanent refractive index change where they overlap. Based on absorption rate measurements, it was confirmed that the pulses were partially absorbed at the overlapping position, with a maximum absorption rate of 6%. Furthermore, a LPFG with a smooth transmission spectrum and low background loss was successfully fabricated using this technique.

Polymer waveguide module for visible wavelength division multiplexing plastic optical fiber communication.

We report a polymer waveguide module that provides bidirectional communication over a single plastic optical fiber (POF) with dual visible wavelength LEDs. The module is constructed using light-induced self-written waveguides, which enables a three-dimensional optical circuit for visible wavelength division multiplexing to be fabricated by an extremely simple process. We demonstrated 250 Mbits/s communication using a pair of these modules that each contained one green (lambda = 495 nm) and one red (lambda = 650 nm) LEDs by measuring the bit error rates. The results indicate that the system could transmit over more than 20 m of POF in full duplex mode.