Compositions and devices for thermooptically controlled switching and filtering
View Patent ↗The invention relates to polymer compositions which enable thermooptic control of signal attenuation in the ultraviolet, visible and near infrared (NIR) regions of the electromagnetic spectrum, and devices incorporating such compositions. The compositions are derived from polymer mixtures which exhibit a cloud point phase transition at a temperature in the range of a thermooptically controlled device such as a programmable waveguide attenuator, a programmable neutral density filter, or an optically absorbent switch. An especially preferred embodiment of the invention comprises a mixture of a high molecular weight chlorotrifluoroethylene fluid and a wax with an “ON-state” insertion loss of below 0.1 dB/cm and an extinction ratio of 22 dB/cm in the 1550 nm NIR telecommunication band.
1. A thermooptically active composition comprising:
10 to 90% by weight of a polymer fluid; and
90 to 10% by weight of a wax having a low melting point,
wherein said composition is thermooptically active having an OFF state at a first temperature wherein said wax is at least partially solidified and said composition is at least partially opaque and an ON state at a second temperature, said second temperature being higher than said first temperature wherein said wax is at least partially fluidized and said composition is at least partially transparent.
2. The composition of claim 1 , wherein the polymer fluid is a chlorotrifluoroethylene polymer.
3. The composition of claim 1 , wherein the polymer fluid is a bromotrifluoroethylene polymer.
4. The composition of claim 1 , wherein the wax is a chlorotrifluoroethylene wax.
5. The composition of claim 1 , wherein the wax is a bromotrifluoroethylene wax.
6. The composition of claim 1 , wherein the polymer fluid is a halogenated polymer, substantially free of hydrogen-bonded species.
7. The composition of claim 1 , wherein the polymer fluid is a halogenated solid which is substantially miscible in the fluid portion when melted.
8. The composition of claim 1 , wherein the polymer fluid is a silicone fluid and the wax is a soluble silicone resin.
9. The composition of claim 1 , wherein the fluid is a polyphenylether and the wax is a high molecular weight polymer of the same type.
10. The composition of claim 1 , wherein the fluid is a polyphenylthiooxyether and the wax is a high molecular weight polymer of the same type.
11. The composition of claim 1 , further comprising:
performance additives up to 5% by weight selected from the group consisting of: anti-oxidant, absorbing dye, fluorescing dye, metal scavenger, metal passivator, acid scavenger and mixtures thereof.
12. The composition of claim 11 further comprising:
fluid thickening agents up to 20% by weight, said fluid thickening agents being soluble in the base fluid.
13. The composition of claim 11 , further comprising:
particle thickening agents up to 50% by weight selected from the group consisting of: silicon dioxide powders, oxide powders, liquid crystals, fluorescent powders, microspheres, nanotubes, clays, metal powders, conductive polymers, chromophoric polymers, ceramic powders and mixtures thereof.
14. The composition of claim 13 further comprising:
fluid thickening agents up to 20% by weight, said fluid thickening agents being soluble in the base fluid.
15. The composition of claim 1 , further comprising:
particle thickening agents up to 50% by weight selected from the group consisting of: silicon dioxide powders, oxide powders, liquid crystals, fluorescent powders, microspheres, nanotubes, clays, metal powders, conductive polymers, chromophoric polymers, ceramic powders and mixtures thereof.
16. The composition of claim 1 further comprising:
fluid thickening agents up to 20% by weight, said fluid thickening agents being soluble in the base fluid.
17. The composition of claim 1 , wherein the fluid is comprised of a blend of two or more miscible constituent fluids.
18. The composition of claim 1 , wherein the fluid is substantially free of carbon-hydrogen bonds.