  We report on tuning the optical whispering gallery modes in a poly dimethyl
siloxane-based (PDMS) microsphere resonator by more than a THz. The PDMS
microsphere system consists of a solid spherical resonator directly formed with
double stems on either side. The stems act like tie-rods for simple mechanical
stretching of the microresonator over tens of microns, resulting in tuning of
the whispering gallery modes by one free spectral range. Further investigations
demonstrate that the whispering gallery mode shift has a higher sensitivity
(0.13 nm/{\mu}N) to an applied force when the resonator is in its maximally
stretched state compared to its relaxed state.
