  Whether it is for transmitting information or for controlling intensity,
light modulation is among the essential functions commonly used in complex
optical systems. In integrated optics, modulation principles usually include
the use of electro-optical effects or acousto-optics varying index waves. Here,
we demonstrate a concept of light-modulation based on a vibrating suspended
cantilever clamped on both ends, acting as an optical waveguide. In this
approach, an optical phase shift is introduced by the physical elongation and
by the stress induced in the vibrating cantilever. Most interesting, such a
device can store optical information in the form of a phase shift, related to
the frequency path-dependence of the vibration. This remarkable property stems
from the intrinsic non-linear dynamical behavior of the device, resembling
Duffing-like oscillators. In this proof-of-concept, the micro-device is
manufactured in a single fused silica chip using femtosecond laser exposure
combined with chemical etching and CO2-laser polishing to achieve optical
roughness quality. The cantilever vibration results from dielectrophoresis
forces arising in the silica beam as a consequence of the non-uniform
electrostatic field applied to it. Noticeably, being made entirely of fused
silica, the device is capable of broadband operation, from the near UV to the
mid-IR range, and this, at kHz frequencies.
