We propose an all fiber tunable band pass filter based on dual acousto-optic mode coupling scheme. By applying two
acoustic waves on a piece of etched single mode fiber, the feasibility of the filter is demonstrated experimentally. The
tunable characteristics of the device are discussed theoretically.
A power equalization using an asymmetric nonlinear amplifying Sagnac interferometer (NASI) for ASK
modulation is studied numerically. A nonreciprocal phase bias was proposed to be introduced into the structure. The
nonreciprocal phase bias reduces not only the demanding for amplifier power or fiber non-linearity, but also increase
the dynamic input power range. The power equalization is demonstrated for RZ modulation by nonlinear phase analysis
and eye diagram simulation.