Critical sensitivity effect in an interferometer sensor

We report the observation of anomalous behavior in the spectral sensitivity response in a specially designed waveguided interferometer sensor. Approaching a definite critical point, the sensitivity increases nonlinearly. Furthermore, at the critical wavelength a new effect of splitting or bifurcation of a minimum dip is observed. The value of the splitting is suggested as an advantageous measure for sensing. (C) 2009 Optical Society of America