Efficient inverse scattering algorithm for the design of grating-assisted codirectional mode couplers

An efficient method for the design of optical devices based on codirectional grating-assisted mode coupling is presented. A low-complexity algorithm is developed to calculate the coupling function of a grating that accurately matches an arbitrarily given target spectral response. The method relies on the synthesis of the grating impulse response by means of an exact differential layer-peeling algorithm.

Measurement of axial stress at high spatial resolution in ultraviolet-exposed fibers.

High-spatial-resolution measurements of axial-stress profiles of UV-irradiated fibers are reported, providing diagnostic information and a technique for the direct observation of UV-written grating structures. Measurements have been made with a spatial resolution of approximately 0.3 microm, which is capable of resolving detail within the pitch of the gratings.

Power measurement of noise-initiated Brillouin scattering in optical fibers for sensing applications.

We discuss the measurement of noise-initiated Brillouin scattered power in optical fibers and its application to distributed sensing systems. In particular, we consider the use of Brillouin scattering in the nonlinear regime, demonstrating a novel processing technique that compensates for the nonlinear growth of the scattered signals. The signal-to-noise ratio performance of this technique is evaluated, highlighting the importance of the noise contributed by the random statistics of the scattered field and yielding the conditions for optimum system operation.