Abstract: An optical frequency conversion element has a wave-guiding layer which consists of a .chi..sup.(2) -active ferroelectric liquid crystal. The monomeric or polymeric liquid crystal material has a periodic structure which permits the so-called quasi phase matching of a guided laser beam. The period length of the structure is equal to twice the coherence length l.sub.c =.pi./.DELTA..beta. of the material, whereby .DELTA..beta.=.beta..sub.o (2.omega.)-2.beta..sub.o (.omega.), with .omega.=angular frequency of the fundamental wave, 0=zero-order mode and .beta.=propagation constant of the mode.

Abstract: Compounds of the formula ##STR1## and liquid crystalline mixtures containing same.

Abstract: A bistable ferroelectric liquid crystal display cell utilizes two plates, a chiral ferroelectric smectic liquid crystal sandwiched between the plates, and an electrode for applying an electrical field to the plates. The chiral ferroelectric smectic liquid crystal has a structure which is influenced by the action of an electric field so that its optical anisotropy changes. By using a first polarizer connected to one of the plates and a second polarizer connected to the other plate, the unique bistable ferroelectric display produces dark parallel stripes when the polarizers are in a cross position relative to each other.

Abstract: Compounds of the general formula ##STR1## wherein R.sup.1 is C.sub.5-12 -alkyl or C.sub.5-12 -alkenyl;R.sup.2 is C.sub.1-9 -alkyl or C.sub.2-9 -alkenyl; provided that at least one of groups R.sup.1 and R.sup.2 is alkenyl;X is a CH group or nitrogen;n is either 0 or 1;q is a whole number between 2 to 6 inclusive;r is either 0 or 1 provided that the sum of q and r at least 3,s is either 0 or 1; andp is either 1 or 2, provided that n is zero when p is 2;mixtures which contain these compounds as well as the use of these compounds for electro-optical purposes.

Abstract: Small-pitch cholesteric liquid crystal mixtures are temperature compensated. They are particularly useful when no, or only a slight, temperature dependence of the selective reflection is permissible, because a considerable temperature dependence would interfere with or render wanted effects impossible. They are composed of a nematic liquid crystal doped with at least two chiral additives satisfying the following conditions:(1) a(c.sub.1 B.sub.1 +c.sub.2 B.sub.2)=b(c.sub.1 A.sub.1 +c.sub.2 A.sub.2)and(2) 1/.lambda..sub.o (T)=a(c.sub.1 A.sub.1 +c.sub.2 A.sub.2)+aT(c.sub.1 B.sub.1 +c.sub.2 B.sub.2)+bT(c.sub.1 A.sub.1 +c.sub.2 A.sub.2)where .lambda..sub.o denotes the mean value of the wavelength band of the selective reflection c.sub.1 c.sub.2, . . . denote the concentrations of the chiral dopants and A.sub.1,B.sub.1 are coefficients of a progression.

Abstract: Compounds of the formula ##STR1## wherein X.sup.1 denotes fluorine or chlorine and X.sup.2 denotes hydrogen, fluorine or chlorine; R.sup.1 is 3E-alkenyl, 4-alkenyl, 2E-alkenyloxy or 3-alkenyloxy; n stands for the number 0 or 1; one of the groups Y.sup.1 and Y.sup.2 is a single covalent bond, --COO--, --OOC--, --CH.sub.2 CH.sub.2 --, --CH.sub.2 O-- or --OCH.sub.2 -- and the other of the groups Y.sup.1 and Y.sup.2 is a single covalent bond; and rings A.sup.1 and A.sup.2 each individually are substituted or unsubstituted trans-1,4-cyclohexylene, in which optionally 2 non-adjacent CH.sub.2 groups are replaced by oxygen, or substituted or unsubstituted 1,4-phenylene, in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; with the proviso that X.sup.2 denotes fluorine or chlorine and/or Y.sup.1 or Y.sup.2 denotes --CH.sub.2 O-- or --OCH.sub.2 -- when simultaneously X.sup.1 is fluorine and R.sup.1 is 3E-alkenyl,and their use for liquid crystalline mixtures and electro-optical purposes.

Abstract: Compounds of the formula ##STR1## wherein Z.sup.1 denotes a single covalent bond or --CH.sub.2 Ch.sub.2 --; ring A.sup.1 represents 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl or, when Z.sup.1 stands for --CH.sub.2 CH.sub.2 --, also trans-1,4-cyclohexylene; X.sup.1 stands for fluorine or chlorine; X.sup.2 signifies fluorine, chlorine or hydrogen, with the proviso that X.sup.2 only signifies hydrogen when X.sup.1 is chlorine or when ring A.sup.1 signifies pyridine-2,5-diyl and Z.sup.1 signifies --CH.sub.2 CH.sub.2 --; and R.sup.1 signifies 1E-alkenyl with 2 to 12 carbon atoms,their manufacture, liquid crystalline mixtures which contain these compounds and their use for electro-optical purposes.

Abstract: Compounds of the formula ##STR1## wherein R.sup.1 is alkyl or trans-4-alkylcyclohexyl andR.sup.2 is alkyl, alkoxy or trans-4-alkylcyclohexyl their preparation, liquid crystalline mixtures containing these compounds and their use for electro-optical purposes.

Abstract: Compounds of the formula ##STR1## wherein n stands for the number 0 or 1; rings A, B and C each independently represent trans-1,4-cyclohexylene, trans-1,3-dioxane-2,5-diyl or unsubstituted or fluoro-substituted 1,4-phenylene; R.sup.1 denotes 3E-alkenyl with 4 to 12 carbon atoms, 4-alkenyl with 5 to 12 carbon atoms or, when ring A represents trans-1,4-cyclohexylene or trans-1,3-dioxane-2,5-diyl, also 1E-alkenyl with 2 to 12 carbon atoms; and R.sup.2 is hydrogen or C.sub.1 -C.sub.10 -alkyl, their manufacture as well as liquid crystalline mixtures which contain such compounds and their use for electro-optical purposes.

Abstract: Optically active compounds of the formula ##STR1## wherein m stands for the number 1 and R.sup.2 is an unsubstituted or halogen-substituted alkyl or alkenyl group in which optionally one methylene group is replaced by oxygen and/or optionally one methylene group is replaced by an ester group --COO-- or --OOC--; or m stands for the number 0 or 1 and R.sup.2 denotes a group of the formula ##STR2## R.sup.1 and R.sup.3 each independently represent an alkyl or alkenyl group in which optionally one methylene group is replaced by oxygen; Z.sup.1, Z.sup.2 and Z.sup.3 each independently are a single covalent bond, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, --COO-- or --OOC--; n stands for the number 0 or 1; rings A.sup.1 an A.sup.2 each independently are unsubstituted or halogen, cyano and/or methyl-substituted 1,4-phenylene in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; and C* denotes a chiral carbon atom; with the proviso that simultaneously R.sup.

Abstract: Optically active compounds of the formula ##STR1## wherein rings A, B and C each independently are unsubstituted or each are 1,4-phenylene substituted with at least one of halogen-, cyano-, methyl- or methoxy in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; R.sup.1 is a radical of an optically active terpene alcohol after cleavage of the hydroxy group or a group --(CH.sub.2).sub.m --C*HX.sup.1 --R.sup.3 ; R.sup.2 is a radical of an optically active terpene alcohol after cleavage of the hydroxy group or a group --(CH.sub.2).sub.n --C*HX.sup.2 --R.sup.4 ; m and n each independently stand for the number O or 1: C* denotes a chiral carbon atom; X.sup.1 and X.sup.2 each independently are fluorine, chlorine, cyano, methyl or methoxy; R.sup.3 and R.sup.4 each independently denote a group R, phenyl or phenyl substituted with R, with the proviso that R.sup.3 is different from X.sup.1 and R.sup.4 is different from X.sup.

Abstract: Compounds of the formula ##STR1## wherein X.sup.1 denotes fluorine or chlorine and X.sup.2 denotes hydrogen, fluorine or chlorine; R.sup.1 is 3E-alkenyl, 4-alkenyl, 2E-alkenyloxy or 3-alkenyloxy; n stands for the number 0 or 1; one of the groups Y.sup.1 and Y.sup.2 is a single covalent bond, --COO--, --OOC--, --CH.sub.2 CH.sub.2 --, --CH.sub.2 O-- or --OCH.sub.2 -- and the other of the groups Y.sup.1 and Y.sup.2 is a single covalent bond; and rings A.sup.1 and A.sup.2 each individually are substituted or unsubstituted trans-1,4-cyclohexylene, in which optionally 2 non-adjacent CH.sub.2 groups are replaced by oxygen, or substituted or unsubstituted 1,4-phenylene, in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; with the proviso that X.sup.2 denotes fluorine or chlorine and/or Y.sup.1 or Y.sup.2 denotes --CH.sub.2 O-- or --OCH.sub.2 -- when simultaneously X.sup.1 is fluorine and R.sup.1 is 3E-alkenyl,and their use for liquid crystalline mixtures and electro-optical purposes.

Abstract: Compounds of formula ##STR1## wherein Z is a single covalent bond or --CH.sub.2 CH.sub.2 --, and R.sup.1 is 1E-alkenyl with 2-12 carbon atoms, liquid crystalline mixtures containing them and their use for electro-optical purposes.

Abstract: Compounds of the formula ##STR1## wherein Z.sup.1 is a single covalent bond or --CH.sub.2 CH.sub.2 --, X.sup.1 is hydrogen, fluorine or chlorine and R.sup.1 is 1E-alkenyl with 2 to 12 carbon atoms,their preparation, liquid crystalline mixtures which contain these compounds and their use for electro-optical purposes.

Abstract: A compound represented by formula (I). ##STR1## wherein R represents a straight chain alkyl group having 1 to 7 carbon atoms; n is an integer of 1 to 5; X represents F, Cl or CN; Y represents H or F; and a dioxane ring in a trans configuration with respect to a cyyclohexane ring.

Abstract: Compounds of the formula ##STR1## wherein n stands for the number 0 or 1; rings A, B and C each independently represent trans-1,4-cyclohexylene, trans-1,3-dioxane-2,5-diyl or unsubstituted or fluoro-substituted 1,4-phenylene; R.sup.1 denotes 3E-alkenyl with 4 to 12 carbon atoms, 4-alkenyl with 5 to 12 carbon atoms or, when ring A represents trans-1,4-cyclohexylene or trans-1,3-dioxane-2,5-diyl, also 1E-alkenyl with 2 to 12 carbon atoms; and R.sup.2 is hydrogen or C.sub.1 -C.sub.10 -alkyl,their manufacture as well as liquid crystalline mixtures which contain such compounds and their use for electro-optical purposes.

Abstract: A compound of the formula ##STR1## wherein Z represents a single covalent bond or --CH.sub.2 --CH.sub.2 --; R.sup.1 denotes alkyl or 2-alkenyl andR.sup.2 is 1E-alkenyl, 3E-alkenyl, 4-alkenyl, (2-alkenyl)oxymethyl or, when R.sup.1 denotes 2-alkenyl and/or Z represents --CH.sub.2 --CH.sub.2 --, R.sup.2 also is alkyl, cyano or alkoxymethyl,as well as the manufacture of the compounds of formula I. Also disclosed is the use of the compounds in liquid crystalline mixtures and for electro-optical purposes.

Abstract: A ferroelectric liquid crystalline mixture containing at least one optically active compound of the general formula ##STR1## wherein X.sup.1 denotes a single covalent bond, --COO--, --OOC--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 -- or --CH.sub.2 O--; one of rings A.sup.1, A.sup.2 and A.sup.3 represents trans-m-dioxan-2,5-diyl and the other two of rings A.sup.1, A.sup.2 and A.sup.3 each independently represent unsubstituted 1,4-phenylene or 1,4-phenylene substituted with cyano, halogen or lower alkyl; R.sup.1 and R.sup.2 each independently signify an optionally halogen-substituted alkyl group with up to 18 carbon atoms in which optionally 1 CH.sub.2 group or 2 non-adjacent CH.sub.2 groups is/are replaced by --O--, --CO--, --COO-- and/or --OOC--,as well as novel compounds falling under formula I and ferroelectric electrode-optical indicating devices including same.

Abstract: Compounds of the formula ##STR1## wherein m represents is the number of 0 to 1; A is a single convalent bond, --CH.sub.2 --CH.sub.2 --, --OCH.sub.2 --, --COO-- or --OOC--; rings B, C and D are 1,4-phenylene optionally substituted with cyano, halogen or lower alkyl; Y.sup.1 and Y.sup.2 are hydrogen or one of them also is cyano; and R.sup.1 and R.sup.2 each represents C.sub.1 -C.sub.18 -alkyl or C.sub.2 -C.sub.18 alkenyl, either of which is optionally halogen-substituted, in which one CH.sub.2 group or two non-adjacent CH.sub.2 groups is/are optionally replaced by oxygen: with the provisos that at least one of R.sup.1 and R.sup.2 has a chiral carbon atom or R.sup.1 is straight-chain C.sub.4-18 -alkoxy and R.sup.2 is straight C.sub.3-18 -alkyl or a C--C double bond or both when A is --COO-- and at least one of R.sup.1 and R.sup.

Abstract: A ferroelectric liquid crystal mixture containing at least one compound of the formula ##STR1## wherein n stands for the number 0 or 1; X.sup.1 represents a single covalent bond, --COO-- or --OOC-- and X.sup.2 represents a single covalent bond, --COO--, --OOC--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 -- or --CH.sub.2 O--; rings A.sup.1, A.sup.2 and A.sup.3 each independently signify 1,4-phenylene optionally substituted with cyano, halogen or lower alkyl or pyrimidin-2,5-diyl, pyrazin-2,5-diyl, when n is 1, trans-1,4-cyclohexylene or trans-m-dioxan-2,5-diyl; with the proviso that one of the rings present stands for pyrimidin-2,5-diyl or pyrazin-2,5-diyl when a further ring signifies trans-1,4-cyclohexylene or when n stands for the number 0 and X.sup.1 stands for a single covalent bond; and R.sup.1 signifies an optionally halogen-substituted alkenyl group with up to 18 carbon atoms in which optionally 1 or 2 non-adjacent CH.sub.2 groups are replaced by --O-- and/or a C.dbd.C double bond; with the proviso that R.