A novel integrated fiber-optic sensor based on a symmetrical twin-core fiber was proposed and demonstrated as a strain
sensor. By heating and tapering the symmetrical twin-core fiber, the light from one core can be partly or completely
coupled into the other core in the coupled zone as the twin-core fiber was pulling. By detecting the output power of any
one core, the strain applied on the twin-core fiber can be detected. The output power of twin core fiber versus the applied
strain was experimentally investigated, and the results showed that the twin-core fiber can be used as a strain sensor.
We design and fabricate an endoscope scanning fiber probe based on the piezoelectric transducer (PZT) for optical
coherence tomography (OCT) to perform two-dimensional scanning. The driving part of the optical fiber probe is
composed of two piezoelectric ceramics and a thin conductive substrate. The optical fiber is fixed in the middle of the
piezoelectric ceramics to form a configuration of cantilever. A sine wave is employed for driving the PZT to make the
cantilever vibrate along the vertical direction and form a line scanning. A saw tooth wave is load on the PZT to make the
cantilever vibrate along the horizontal direction and form the field scanning. The frequency of the sine wave is set to be
close to the resonance frequency of the fiber cantilever to increase the scanning range, whereas the frequency of the saw
tooth wave is much lower than the resonance frequency to avoid the generation of blind spots. The finite element model
is established for the theorical analysis of the device. Experimental results show that the scanning range can reach to
500x500 μm, and the scanning range can be adjusted by changing the amplitude of the drive signals.