The
refractive index modulation (Δn) of
photopolymers is a key performance indicator in determining their
application potentials in holographic optical elements (HOEs). In
this study, four fluoroelastomers (HT-HS, HT-F185, HT-L80, and HT-F197)
containing hydroxyl groups as active functional groups are selected
to construct low refractive index host matrices with isocyanates.
Through a combination of them with high refractive index monomers,
a series of transparent photopolymers are obtained. Among them, one
containing 16 wt % HT-F197 has the highest sensitivity, which can
record a transmission volume holographic grating (VHG) with high resolution
(3600 lines/mm) and diffraction efficiency (95.76%) under exposure
of a 532 nm laser. Its Δn is up to 0.054. Furthermore,
a reflection VHG with high performance (4900 lines/mm resolution and
92.32% diffraction efficiency) can also be achieved. After photobleaching,
its transmittance within 400–800 nm reaches 96.21%, showing
great potential in the fabrication of transparent HOEs.