  The present work deals with a curvature sensor that consists of two segments
of asymmetric multicore fiber (MCF) fusion spliced with standard single mode
fiber (SMF). The MCF comprises three strongly coupled cores; one of such cores
is at the geometrical center of the MCF. The two segments of MCF are short,
have different lengths (less than 2 cm each), and are rotated 180 degrees with
respect to each other. The fabrication of the sensor was carried out with a
fusion splicing machine that has the means for rotating optical fibers. It is
demonstrated that the sensor behaves as two SMF-MCF-SMF structures in series,
and consequently, it has enhanced sensitivity. The device proposed here can be
used to sense the direction and amplitude of curvature by monitoring either
wavelength shifts or intensity changes. In the latter case, high curvature
sensitivity was observed. The device can also be used for the development of
other highly sensitive sensors to monitor, for example, vibrations, force,
pressure, or any other parameter that induces periodic or local curvature or
bending to the MCF segments.
