Switchable volume hologram materials and devices

An optical switch comprising:

• two cross polarizers;
• and
• a half-wave plate interposed between the two cross polarizers, the half-wave plate comprising a plurality of periodic planes of polymer channels and polymer-dispersed liquid crystal (PDLC) channels, wherein the PDLC channels and polymer channels are disposed perpendicular to a front surface of the optical switch,
• wherein the optical switch passes incident light absent a switching voltage and blocks incident light when a switching voltage is applied to the optical switch.

An optical switch comprising:

• a beam splitter;
• a mirror;
• and
• a quarter-wave plate interposed between the beam splitter and the mirror, the quarter-wave plate comprising a plurality of periodic planes of polymer channels and polymer-dispersed liquid crystal (PDLC) channels, wherein the PDLC channels and polymer channels are disposed perpendicular to a front surface of the grating,
• wherein the beam splitter reflects reflected light from the mirror absent a switching voltage, and when a switching voltage is applied to the optical switch, reflected light passes through the beam splitter and is retroreflected on the incident beam.

A method for reducing the switching voltage of a single electrically switchable subwavelength grating comprising:

• stacking together a plurality of single electrically switchable subwavelength gratings, each electrically switchable subwavelength grating comprising a plurality of periodic planes of polymer channels and polymer-dispersed liquid crystal (PDLC) channels, wherein the PDLC channels and polymer channels are disposed perpendicular to a front surface of the electrically switchable subwavelength grating;
• electrically connecting the stack of single electrically switchable subwavelength gratings in parallel;
• and
• applying an electric field in order to switch the stack of single electrically switchable subwavelength gratings between an on state and off state, wherein the electric field required to switch the stack of single electrically switchable subwavelength gratings is lower than an electric field required to switch a single electrically switchable subwavelength grating.