Active tapered double-clad fiber with low birefringence.

We addressed the problem of a state of polarization (SOP) drift caused by heating under intense clad pumping in different types of active tapered double-clad fibers. We investigated experimentally the variations of the SOP and degree of polarization (DOP) under clad pumping in polarization-maintaining (PANDA type) and regular (non-PM) Yb-doped double-clad large mode area tapered fibers. We discovered that the birefringence of active fibers is highly dependent on the launched pump power.

All-Fiber Highly Sensitive Bragg Grating Bend Sensor.

In this paper, we demonstrated a novel, all-fiber highly sensitive bend sensor based on a four-core fiber rod with a diameter of 2.1 mm. We observed a high resolution of the sensor at a level of 3.

Mode evolution in long tapered fibers with high tapering ratio.

We have experimentally studied fundamental mode propagation in few meters long, adiabatically tapered step-index fibers with high numerical aperture, core diameter up to 117 μm (V = 38) and tapering ratio up to 18. The single fundamental mode propagation was confirmed by several techniques that reveal no signature of higher-order mode excitation. It can be, therefore, concluded that adiabatic tapering is a powerful method for selective excitation of the fundamental mode in highly multimode large-mode-area fibers.

Dispersion compensation technologies for femtosecond fiber system.

Developed highly chirped broadband fiber Bragg gratings and suspended-core fibers are shown to offer flexible dispersion management and allow for femtosecond oscillators with transform-limited pulse quality. Such dispersion compensators could have potential, particularly for all-fiber chirped-pulse amplification systems.