  We proposed an optomechanical system to quantify the net force on a strand of
cleaved silica optical fiber in situ as the laser light was being guided
through it. Four strands of the fiber were bond to both sides of a macroscopic
oscillator, whose movements were accurately monitored by a Michelson
interferometer. The laser light was propagating with variable optical powers
and frequency modulations. Experimentally we discovered that the driving force
for the oscillator consisted of not only the optical force of the light exiting
from the cleaved facets but also the tension along the fiber induced by the
light guided therewithin. The physical principle to understand how the forces
of the light guided through an optical fiber drove the macroscopic oscillator
is explained and compared with Abraham-Minkowski light momentum theories.
