We present long period fiber gratings which are constructed of periodic changes in the fiber diameter. Our long period fiber gratings induce strong coupling between the different modes and as such have wider bandwidth and even off-resonance spectral response. We present both calculated and measured results of these long period fiber gratings.
We present fusing of fiber micro-knot by CO2 laser which fixes the micro-fibers in place and stabilizing the micro-knot shape, size and orientation. This fusing enables tuning of the coupling strength, the free-spectral range and the birefringence of the fiber micro-knot. Fused micro-knots are superior over regular micro-knots and we believe that fusing of micro-knots should be a standard procedure in fabricating fiber micro-knots.