  Experiments based on free space platform have demonstrated that the weak
value amplification (WVA) technique can provide high sensitivity and precision
for optical sensing and metrology. To promote this technique for real-world
applications, it is more suitable to implement WVA based on optical fiber
platform due to the lower cost, smaller scale and higher stability. In contrast
to the free space platform, the birefringence in optical fiber is strong enough
to cause polarization cross talk, and the amplitude-type noise must be taken
into account. By theoretical analysis and experimental demonstration, we show
that the optic-fiber-based WVA is robust in presence of amplitude-type noise.
In our experiment, even the angular misalignment on optical axes at the
interface reaches 0.08rad, the sensitivity loss can be maintained less than
3dB. Moreover, the main results are valid to a simplified detection scheme that
recently proposed, which is more compatible with the future design of
optical-fiber based WVA. Our results indicate the feasibility of implementing
WVA based on optical fiber, which provide a possible way for designing optical
sensors with higher sensitivity and stability in the future.
