Optical component

Abstract

An optical component is described which contains a liquid crystal (LC) medium, operable in the infrared region of the electromagnetic spectrum. The LC medium, which can be used in the infrared (IR) region, can contain one or more compounds of the formulae I, II, and III ##STR00001## in which the occurring groups and parameters have the meanings defined herein, and preferably contain one or more compounds of the formula RO ##STR00002## in which the occurring groups and parameters have the meanings defined herein.

Claims

1. An optical component (100) operable in the infrared region of the electromagnetic spectrum comprising: a liquid crystal medium (140) sandwiched between a first substrate (110) and a second substrate (160) facing each other, and first and second electrodes (120, 150) for supplying an electric potential across said liquid crystal medium to drive liquid crystals in a predetermined configuration, wherein said liquid crystal medium comprises: one or more compounds selected from formulae I, II, and III ##STR00328## in which R.sup.1 denotes H, or a straight chain alkyl having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain alkenyl having 2 to 15 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00329## n is 0, 1 or 2, ##STR00330## on each occurrence, independently of one another, denote ##STR00331## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein ##STR00332## alternatively denotes ##STR00333## R.sup.2 denotes H, or a straight chain having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain having 1 to 12 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00334## Z.sup.21 denotes trans-CHCH, trans-CFCF or CC, and ##STR00335## independently of one another, denote ##STR00336## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein R.sup.3 denotes H, a straight chain alkyl having 1 to 12 C, a branched alkyl having 3 to 12 C atoms, a straight chain alkenyl having 2 to 15 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00337## one of Z.sup.31 and Z.sup.32, denotes trans-CHCH, trans-CFCF or CC and the other one, independently thereof, denotes CC, trans-CHCH, trans-CFCF or a single bond; ##STR00338## independently of one another, denote ##STR00339## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein ##STR00340## alternatively denotes ##STR00341## one or more compounds of formula RO ##STR00342## in which R.sup.RO denotes straight chain having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain alkenyl having 2 to 12 C atoms, or a branched alkenyl having 3 to 12 C atoms, in each of which one or more CH.sub.2-groups may each be replaced by ##STR00343## Z.sup.T1, Z.sup.T2 identically or differently, denote CHCH, CFCF, CHCF, CFCH, CC or a single bond, X.sup.1, X.sup.2, X.sup.3 and X.sup.4 identically or differently, denote H, Cl, F or CH.sub.3, t is 0 or 1, and ##STR00344## denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-naphthylene, in which one or two CH groups may each be replaced by N and in which one or more H atoms may each be replaced by L, b) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, furan-2,5-diyl, each of which is optionally mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, a straight-chain alkyl or alkoxy, in each case optionally fluorinated, having 1 to 12 C atoms, a branched alkyl or alkoxy having 3 to 12 C atoms, a straight-chain alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 2 to 12 C atoms, or branched alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 2 4 to 12 C atoms; wherein said medium contains one or more compounds of the formula I in a total concentration of 30% or more, and said medium contains one or more compounds of formula III in a total concentration of 2% to 30%.

2. The component comprising a liquid crystal medium according to claim 1, wherein the liquid crystal medium comprises one or more compounds of formula T ##STR00345## in which R.sup.T denotes halogen, CN, NCS, R.sup.F, R.sup.FO or R.sup.FS, wherein R.sup.F denotes fluorinated alkyl or fluorinated alkenyl having up to 12 C atoms, ##STR00346## on each occurrence, independently of one another, denote ##STR00347## L.sup.4 and L.sup.5 identically or differently, denote F, Cl or straight chain alkyl having 1 to 12 C atoms, branched alkyl having 3 to 12 C atoms, cyclic alkyl having 3 to 12 C atoms, or straight chain alkenyl having 2 to 12 C atoms, branched alkenyl having 3 to 12 C atoms, or cyclic alkenyl having 3 to 12 C atoms; Z.sup.T3, Z.sup.T4 identically or differently, denote CHCH, CFCF, CHCF, CFCH, CC or a single bond, and t is 0 or 1.

3. The component comprising a liquid crystal medium according to claim 1, wherein the liquid crystal medium is a polymer network liquid crystal, comprising a polymer network obtainable by in situ polymerization from the liquid crystal medium as set forth in claim 1, the liquid crystal medium further comprising one or more compounds of formula P
P.sup.a(Sp.sup.a).sub.s1-A.sup.2-(Z.sup.a-A.sup.1).sub.n2-(Sp.sup.b).sub.s2-P.sup.bP in which the individual radicals have the following meanings: P.sup.a P.sup.b each, independently of one another, denote a polymerizable group, Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group, s1, s2 each, independently of one another, denote 0 or 1, A.sup.1, A.sup.2 each, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclo-hexenylene and 4,4-bicyclohexylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O and/or S and wherein, in addition, one or more H atoms may be each replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, wherein, in addition, one or two CH groups may each be replaced by N and wherein, in addition, one or more H atoms may each be replaced by L, c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals having 5 to 20 cyclic C atoms, one or more of which may, in addition, be replaced by heteroatoms, n2 denotes 0, 1, 2 or 3, Z.sup.a in each case, independently of one another, denotes COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, or (CH.sub.2).sub.n, where n is 2, 3 or 4, O, CO, C(R.sup.yR.sup.z), CH.sub.2CF.sub.2, CF.sub.2CF.sub.2 or a single bond, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 12 C atoms, and R.sup.y, R.sup.z each, independently of one another, denote H, F or straight-chain or branched alkyl having up to 12 C atoms, in which one or more H atoms may each be replaced by F.

4. The component comprising a liquid crystal medium according to claim 1, wherein the liquid crystal medium comprises a chiral dopant.

5. The component comprising a liquid crystal medium according to claim 1, wherein the liquid crystal medium comprises a stabilizer.

6. The component according to claim 1, wherein the component is a transmissive spatial light modulator.

7. The component according to claim 1, wherein the component is a reflective spatial light modulator configured to modulate the phase of an incident optical signal propagating at least partially in a first dimension, wherein the first substrate is a transparent glass layer having a first, transparent electrode, and wherein the second substrate is a complementary metal-oxide-semiconductor (CMOS) silicon backplane, the component further comprising a mirror disposed between the second substrate and the liquid crystal medium, wherein the mirror is divided into a two-dimensional array of individually addressable pixels arranged and configured as second electrodes, each pixel being individually drivable by a voltage signal to provide a local phase change to at least one polarization component of an optical signal.

8. A liquid-crystal-on-silicon (LCoS) device, wherein said device comprises a component according to claim 7.

9. A wavelength selective switch, light detection and ranging (LIDAR) scanner, infrared scene projector, wavelength-division multiplexing system, reconfigurable optical add-drop multiplexer, or electro evanescent optical refraction prism comprising a liquid-crystal-on-silicon (LCoS) device according to claim 8.

10. A method of spatially modulating infrared light, the method comprising: i) providing an optical component according to claim 1; ii) receiving incident infrared light at a surface of said optical component; and iii) applying a predetermined voltage to each of the individual electrodes formed on the first substrate in order to modulate a refractive index of the liquid crystal medium.

11. A method of manufacturing an optical phase modulator, comprising: a) providing a first substrate with a first electrode, optionally having a two dimensional array of individually electrically drivable cells; b) depositing a liquid crystal medium over the first substrate; and c) mounting a second substrate with a second electrode onto the liquid crystal material, wherein said liquid crystal medium comprises: one or more compounds selected from formulae I, II, and III ##STR00348## in which R.sup.1 denotes H, or a straight chain alkyl having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain alkenyl having 2 to 15 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00349## n is 0, 1 or 2, ##STR00350## on each occurrence, independently of one another, denote ##STR00351## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein ##STR00352## alternatively denotes ##STR00353## R.sup.2 denotes H, or a straight chain having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain having 1 to 12 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00354## Z.sup.21 denotes trans-CHCH, trans-CFCF or CC, and ##STR00355## independently of one another, denote ##STR00356## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein R.sup.3 denotes H, a straight chain alkyl having 1 to 12 C, a branched alkyl having 3 to 12 C atoms, a straight chain alkenyl having 2 to 15 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00357## one of Z.sup.31 and Z.sup.32, denotes trans-CHCH, trans-CFCF or CC and the other one, independently thereof, denotes CC, trans-CHCH, trans-CFCF or a single bond; ##STR00358## independently of one another, denote ##STR00359## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein ##STR00360## alternatively denotes ##STR00361## one or more compounds of formula RO ##STR00362## in which R.sup.RO denotes straight chain having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain alkenyl having 2 to 12 C atoms, or a branched alkenyl having 3 to 12 C atoms, in each of which one or more CH.sub.2-groups may each be replaced by ##STR00363## Z.sup.T1, Z.sup.T2 identically or differently, denote CHCH, CFCF, CHCF, CFCH, CC or a single bond, X.sup.1, X.sup.2, X.sup.3 and X.sup.4 identically or differently, denote H, Cl, F or CH.sub.3, t is 0 or 1, and ##STR00364## denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-naphthylene, in which one or two CH groups may each be replaced by N and in which one or more H atoms may each be replaced by L, b) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, furan-2,5-diyl, each of which is optionally mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, a straight-chain alkyl or alkoxy, in each case optionally fluorinated, having 1 to 12 C atoms, a branched alkyl or alkoxy having 3 to 12 C atoms, a straight-chain alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 2 to 12 C atoms, or branched alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 2 4 to 12 C atoms; wherein said medium contains one or more compounds of the formula I in a total concentration of 30% or more, and said medium contains one or more compounds of formula III in a total concentration of 2% to 30%.

12. The optical component according to claim 1, wherein said medium contains one or more compounds of formula II.

13. The optical component according to claim 12, wherein one or more compounds of formula II are selected from the formulae II-1 to II-3: ##STR00365## wherein R.sup.2 denotes H, or a straight chain having 1 to 12 C atoms, a branched alkyl having 3 to 12 C atoms, a straight chain having 1 to 12 C atoms, or a branched alkenyl having 3 to 15 C atoms, in which one or more CH.sub.2-groups may each be replaced by ##STR00366## ##STR00367## independently of one another, denote ##STR00368## R.sup.L denotes H or alkyl having 1 to 6 C atoms.

14. The optical component according to claim 12, wherein said one or more compounds formula RO are selected from compounds of formulae RO-1 to RO-7 ##STR00369## wherein X.sup.1 and X.sup.2 denote H, Cl, F or CH.sub.3.

15. The optical component according to claim 13, wherein said one or more compounds formula RO are selected from compounds of formulae RO-1 to RO-7 ##STR00370## wherein X.sup.1 and X.sup.2 denote H, Cl, F or CH.sub.3.

16. The optical component according to claim 14, wherein said medium contains one or more compounds of formula II and/or formula RO-2, in a total concentration of 5% to 40%.

17. The optical component according to claim 15, wherein said medium contains one or more compounds of formula II-1 and/or formula RO-2, in a total concentration of 5% to 40%.

18. The optical component according to claim 1, wherein the liquid crystal medium is a polymer network liquid crystal, comprising a polymer network obtainable by in situ polymerization from the liquid crystal medium as set forth in claim 1, the liquid crystal medium further comprising one or more compounds of formula P
P.sup.a(Sp.sup.a).sub.s1-A.sup.2-(Z.sup.a-A.sup.1).sub.n2-(Sp.sup.b).sub.s2-P.sup.bP in which the individual radicals have the following meanings: P.sup.a, P.sup.b each, independently of one another, denote a polymerizable group, Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group, s1, s2 each, independently of one another, denote 0 or 1, A.sup.1, A.sup.2 each, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclo-hexenylene and 4,4-bicyclohexylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O and/or S and wherein, in addition, one or more H atoms may be each replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, wherein, in addition, one or two CH groups may each be replaced by N and wherein, in addition, one or more H atoms may each be replaced by L, c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals selected from the group consisting of ##STR00371## where one or more H atoms in these radicals may each be replaced by L, and/or one or more double bonds may each be replaced by single bonds, and/or one or more CH groups may each be replaced by N, n2 denotes 0, 1, 2 or 3, Z.sup.a in each case, independently of one another, denotes COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, or (CH.sub.2).sub.n, where n is 2, 3 or 4, O, CO, C(R.sup.yR.sup.z), CH.sub.2CF.sub.2, CF.sub.2CF.sub.2 or a single bond, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 12 C atoms, R.sup.y, R.sup.z each, independently of one another, denote H, F or straight-chain or branched alkyl having up to 12 C atoms, in which one or more H atoms may each be replaced by F, M denotes O, S, CH.sub.2, CHY.sup.1 or CY.sup.1Y.sup.2, and Y.sup.1 and Y.sup.2 each, independently of one another, denote H, F or straight-chain or branched alkyl having up to 12 C atoms, in which one or more H atoms may each be replaced by F, or denote Cl or CN.

Description

EXAMPLES

(1) Comparative Mixture C1 and Example mixtures N1 to N22 for use according to the invention having the compositions and properties as indicated in the following tables are prepared and characterized with respect to their general physical properties and their applicability in optical components.

(2) An optical component comprising the media according to the invention as defined in claim 1, and fabricated according to the process as defined in claim 12 is distinguished by excellent operational stability when exposed to the environment because of high clearing temperature, broad nematic phase range and excellent low-temperature stability (LTS) of the liquid crystal medium used therein. As a result, the component, and devices containing the component, are operable under extreme temperature conditions. Surprisingly, the temperature dependence of the birefringence of said liquid crystal medium is very small, i.e. the n changes little with the temperature which makes a device reliable and easy to control.

(3) TABLE-US-00004 Comparative Mixture C1 CP-1V-N 12.0% T.sub.N,I [ C.]: 111 ME3N.F 3.0% n [589.3 nm, 20 C.] 0.2939 ME4.NF 13.0% n.sub.e [589.3 nm, 20 C.] 1.8139 PTP-1-O2 4.0% n.sub.o [589.3 nm, 20 C.] 1.5200 PTP-2-O1 5.0% [1 kHz, 20 C.]: 13.4 PTP-3-O1 5.0% .sub. [1 kHz, 20 C.]: 17.8 CPTP-3-O1 3.0% .sub. [1 kHz, 20 C.]: 4.4 PPTUI-3-2 20.0% .sub.1 [mPas, 20 C.]: 334 PPTUI-3-4 35.0% K.sub.1 [pN, 20 C.]: 13.0 100.0% K.sub.3 [pN, 20 C.]: 16.5 K.sub.3/K.sub.1 [pN, 20 C.]: 1.27 V.sub.0 [V, 20 C.]: 1.04 LTS.sub.bulk (20 C.) 192

(4) TABLE-US-00005 Example N1 PTU-3-S 15.0% T.sub.N,I [ C.]: 124.5 PTU-5-S 15.0% n [589.3 nm, 20 C.] 0.3628 PGU-3-S 15.0% n.sub.e [589.3 nm, 20 C.] 1.9034 PPTU-5-S 10.0% n.sub.o [589.3 nm, 20 C.] 1.5406 CPU-2-S 28.0% [1 kHz, 20 C.]: 22.0 CPU-4-S 17.0% .sub. [1 kHz, 20 C.]: 26.7 100.0% .sub. [1 kHz, 20 C.]: 4.6 .sub.1 [mPas, 20 C.]: 307 K.sub.1 [pN, 20 C.]: 14.5 K.sub.3 [pN, 20 C.]: 18.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.24 V.sub.0 [V, 20 C.]: 0.85 LTS.sub.bulk (20 C.) >1000

(5) TABLE-US-00006 Example N2 PTU-3-S 10.0% T.sub.N,I [ C.]: 149.5 PTU-5-S 8.0% n [589.3 nm, 20 C.] 0.3838 PGU-3-S 18.0% n.sub.e [589.3 nm, 20 C.] 1.9232 PPTU-4-S 7.0% n.sub.o [589.3 nm, 20 C.] 1.5394 PPTU-5-S 9.0% [1 kHz, 20 C.]: 23.3 PGTU-4-S 6.0% .sub. [1 kHz, 20 C.]: 27.7 CPU-2-S 22.0% .sub. [1 kHz, 20 C.]: 4.5 CPU-4-S 20.0% .sub.1 [mPas, 20 C.]: 394 100.0% K.sub.1 [pN, 20 C.]: 16.8 K.sub.3 [pN, 20 C.]: 20.6 K.sub.3/K.sub.1 [pN, 20 C.]: 1.23 V.sub.0 [V, 20 C.]: 0.90 LTS.sub.bulk (20 C.) >1000 LTS.sub.bulk (30 C.) 768 LTS.sub.bulk (40 C.) 96

(6) The birefringence of comparative mixture C-1 and of mixture examples N-1 and N-2 are determined at 20 C. and 60 C. The results are shown in Table 1.

(7) TABLE-US-00007 TABLE 1 Mixture n.sub.20 n.sub.60 n.sub.20/n.sub.60 C-1 0.2939 0.2511 1.170 N-2 0.3838 0.3538 1.085 N-3 0.4267 0.3951 1.080

(8) Surprisingly, the ratio n.sub.20/n.sub.60 is favorably smaller for the media according to the invention, i.e. they show less variation of the birefringence with temperature compared to the medium of the state of the art.

(9) TABLE-US-00008 Example N3 PTU-3-S 10.0% T.sub.N,I [ C.]: 156 PTU-5-S 11.0% n [589.3 nm, 20 C.] 0.4267 PPTU-4-S 6.0% [1 kHz, 20 C.]: 18.8 PPTU-5-S 10.0% .sub. [1 kHz, 20 C.]: 22.8 PGTU-4-S 6.0% .sub. [1 kHz, 20 C.]: 4.0 PGU-3-S 12.0% .sub.1 [mPas, 20 C.]: 461 PPU-TO-S 23.0% K.sub.1 [pN, 20 C.]: 17.0 CPTU-5-S 22.0% K.sub.3 [pN, 20 C.]: 25.0 100.0% K.sub.3/K.sub.1 [pN, 20 C.]: 1.47 V.sub.0 [V, 20 C.]: 1.01

(10) TABLE-US-00009 Example N4 PTU-3-S 10.0% T.sub.N,I [ C.]: 152 PTU-5-S 11.0% n [589.3 nm, 20 C.] 0.4263 PPTU-4-S 6.0% [1 kHz, 20 C.]: 18.5 PPTU-5-S 5.0% .sub. [1 kHz, 20 C.]: 22.6 PPTU-(c3)1-S 5.0% .sub. [1 kHz, 20 C.]: 4.1 PGTU-4-S 6.0% .sub.1 [mPas, 20 C.]: 472 PGU-3-S 12.0% K.sub.1 [pN, 20 C.]: 16.9 PPU-TO-S 23.0% K.sub.3 [pN, 20 C.]: 24.8 CPTU-5-S 22.0% 100.0%

(11) TABLE-US-00010 Example N5 PTU-3-S 12.0% PTU-5-S 12.0% PPTU-4-S 6.0% PPTU-5-S 5.0% PPTU-(c3)1-S 6.0% PGTU-4-S 6.0% PGU-3-S 12.0% PPU-TO-S 23.0% CPTU-(c3)1-S 18.0% 100.0%

(12) TABLE-US-00011 Example N6 PTU-3-S 12.0% PTU-5-S 12.0% PPTU-4-S 6.0% PPTU-5-S 5.0% PTPU-(c3) 1-S 6.0% PGTU-4-S 6.0% PGU-3-S 12.0% PPU-TO-S 23.0% CPTU-(c3)1-S 18.0% 100.0%

(13) TABLE-US-00012 Example N7 PTU-3-S 10.0% T.sub.N,I [ C.]: 155.5 PTU-4O-S 8.0% n [589.3 nm, 20 C.] 0.3874 PTU-3-S 18.0% [1 kHz, 20 C.]: 24.0 PPTU-4-S 7.0% PPTU-5-S 9.0% PGTU-4-S 6.0% CPU-2-S 22.0% CPU-4-S 20.0% 100.0%

(14) TABLE-US-00013 Example N8 PTU-2O-S 8.0% T.sub.N,I [ C.] 155.5 PTU-4O-S 10.0% n [589.3 nm, 20 C.] 0.3874 PGU-3-S 18.0% [1 kHz, 20 C.] 24.0 PPTU-4-S 7.0% PPTU-5-S 9.0% PGTU-4-S 6.0% CPU-2-S 22.0% CPU-4-S 20.0% 100.0%

(15) TABLE-US-00014 Example N9 PTG-2O-S 8.0% T.sub.N,I [ C.] 162.5 PTG-4O-S 8.0% n [589.3 nm, 20 C.] 0.3919 PTU-2O-S 8.0% [1 kHz, 20 C.] 24.6 PTU-4O-S 10.0% PGU-3-S 15.0% PPTU-4-S 10.0% PPTU-5-S 9.0% PGTU-4-S 6.0% CPU-2-S 6.0% CPU-4-S 20.0% 100.0%

(16) TABLE-US-00015 Example N10 PTG-2O-S 8.0% T.sub.N,I [ C.] 148.0 PTG-4O-S 8.0% n [589.3 nm, 20 C.] 0.4191 PTU-2O-S 8.0% PTU-(c3)1-O-S 10.0% PGU-3-S 15.0% PPTU-4-S 10.0% PPTU-5-S 9.0% PGTU-4-S 6.0% CPU-2-S 6.0% CPU-4-S 20.0% 100.0%

(17) TABLE-US-00016 Example N11 PTG-2O-S 8.0% T.sub.N,I [ C.]: 157.0 PTG-4O-S 8.0% n [589.3 nm, 20 C.] 0.4114 PTU-4O-S 10.0% [1 kHz, 20 C.]: 24.1 PGU-3-S 18.0% PPTU-4-S 10.0% PPTU-5-S 9.0% PGTU-4-S 6.0% CPU-2-S 11.0% CPU-4-S 20.0% 100.0%

(18) TABLE-US-00017 Example N12 PTU-3-S 15.0% T.sub.N,I [ C.]: 135.5 PTU-4O-S 15.0% n [589.3 nm, 20 C.] 0.3696 PGU-3-S 15.0% PPTU-5-S 10.0% CPU-2-S 28.0% CPU-4-S 17.0% 100.0%

(19) TABLE-US-00018 Example N13 PTU-3-S 5.0% T.sub.N,I [ C.]: 143.0 PTU-2O-S 10.0% n [589.3 nm, 20 C.] 0.3746 PTU-4O-S 15.0% PGU-3-S 15.0% PPTU-5-S 10.0% CPU-2-S 28.0% CPU-4-S 17.0% 100.0%

(20) TABLE-US-00019 Example N14 PTG-2O-S 10.0% T.sub.N,I [ C.]: 147.0 PTG-4O-S 10.0% n [589.3 nm, 20 C.] 0.3812 PTU-4O-S 10.0% PGU-3-S 15.0% PPTU-5-S 10.0% CPU-2-S 28.0% CPU-4-S 17.0% 100.0%

(21) TABLE-US-00020 Example N14 PTG-2O-S 8.0% T.sub.N,I [ C.]: 143.0 PTG-4O-S 8.0% n [589.3 nm, 20 C.] 0.3865 PTU-2O-S 8.0% [1 kHz, 20 C.]: 24.2 PTU-4O-S 10.0% PGU-3-S 15.0% PPTU-5-S 10.0% CPU-2-S 28.0% CPU-4-S 13.0% 100.0%

(22) TABLE-US-00021 Example N16 PTU-3-S 10.0% T.sub.N,I [ C.]: 164 PTU-4O-S 11.0% n [589.3 nm, 20 C.] 0.4316 PPTU-4-S 6.0% [1 kHz, 20 C.]: 20.0 PPTU-5-S 10.0% PGTU-4-S 6.0% PGU-3-S 12.0% PPU-TO-S 23.0% CPTU-5-S 22.0% 100.0%

(23) TABLE-US-00022 Example N17 PTU-2O-S 8.0% T.sub.N,I [ C.]: 172.5 PTU-4O-S 12.0% n [589.3 nm, 20 C.] 0.4358 PPTU-4-S 6.0% [1 kHz, 20 C.]: 23.3 PPTU-5-S 10.0% PGTU-4-S 6.0% PGU-3-S 13.0% PPU-TO-S 23.0% CPTU-5-S 22.0% 100.0%

(24) TABLE-US-00023 Example N18 PTG-2O-S 8.0% T.sub.N,I [ C.]: 162 PTG-4O-S 8.0% n [589.3 nm, 20 C.] 0.4459 PTU-2O-S 8.0% [1 kHz, 20 C.]: 20.6 PTU-4O-S 10.0% PPTU-4-S 6.0% PPTU-5-S 10.0% PGTU-4-S 6.0% PPU-TO-S 23.0% CPTU-5-S 22.0% 100.0%

(25) TABLE-US-00024 Example N19 PTG-2O-S 8.0% T.sub.N,I [ C.]: 167.5 PTG-4O-S 8.0% n [589.3 nm, 20 C.] 0.4420 PTU-4O-S 10.0% [1 kHz, 20 C.]: 19.5 PPTU-4-S 6.0% PPTU-5-S 10.0% PGTU-4-S 6.0% PGU-3-S 7.0% PPU-TO-S 23.0% CPTU-5-S 22.0% 100.0%

(26) TABLE-US-00025 Example N20 PTG-(c3)1O-S 8.0% T.sub.N,I [ C.]: 158 PTG-4O-S 7.0% n [589.3 nm, 20 C.] 0.4457 PTU-2O-S 8.0% PTU-4O-S 10.0% PPTU-4-S 6.0% PPTU-5-S 10.0% PGTU-4-S 6.0% PPU-TO-S 23.0% CPTU-5-S 22.0% 100.0%

(27) TABLE-US-00026 Example N21 PTU-3-S 12.0% T.sub.N,I [ C.]: 141.5 PTU-5-S 12.0% n [589.3 nm, 20 C.] 0.3981 PPTU-4-S 8.0% n.sub.e [589.3 nm, 20 C.] 1.9377 PPTU-5-S 8.0% n.sub.o [589.3 nm, 20 C.] 1.5396 PGTU-4-S 10.0% [1 kHz, 20 C.]: 21.3 PGU-3-S 10.0% .sub. [1 kHz, 20 C.]: 25.7 PPU-TO-S 10.0% .sub. [1 kHz, 20 C.]: 4.4 CPU-2-S 15.0% .sub.1 [mPa s, 20 C.]: 364 CPU-4-S 15.0% K.sub.1 [pN, 20 C.]: 16.0 100.0% K.sub.3 [pN, 20 C.]: 20.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.25 V.sub.0 [V, 20 C.]: 0.91

(28) TABLE-US-00027 Example N22 PTU-3-S 12.0% T.sub.N,I [ C.]: 141.5 PTU-5-S 12.0% n [589.3 nm, 20 C.] 0.4108 PPTU-4-S 6.0% n.sub.e [589.3 nm, 20 C.] 1.9500 PPTU-5-S 14.0% n.sub.o [589.3 nm, 20 C.] 1.5392 PGTU-4-S 6.0% [1 kHz, 20 C.]: 21.1 PGU-3-S 15.0% .sub. [1 kHz, 20 C.]: 25.4 PPU-TO-S 15.0% .sub. [1 kHz, 20 C.]: 4.4 CPU-2-S 12.0% .sub.1 [mPa s, 20 C.]: 380 CPU-4-S 8.0% K.sub.1 [pN, 20 C.]: 16.6 100.0% K.sub.3 [pN, 20 C.]: 21.4 K.sub.3/K.sub.1 [pN, 20 C.]: 1.29 V.sub.0 [V, 20 C.]: 0.94

(29) Furthermore, the media according to the invention are distinguished by a high clearing temperature in combination with excellent low temperature stability, i.e. they have a very broad operating temperature range.

(30) Furthermore, the media according to the invention show a surprisingly low threshold voltage V.sub.0.

(31) Surprisingly, a medium comprising a compound RO with an alkoxy side chain has an even higher birefringence and higher clearing temperature than a medium comprising exclusively compounds with an alkyl side chain.