Abstract: For reducing power consumption and cross-talk in the transmission of broadband optical signals without prior conversion into electrical signals there are provided in a thermo-optical switch two waveguides (WL1 and WL2) extending closely adjacent each other over their interactive length the width of which is at least partially covered by one or two pairs of lamellate electrode arms of a heating electrode (E), the arms of each pair being interconnected by a common web (G) and being of similar geometric shape as the waveguides (WL1 and WL2) positioned below them. Furthermore, means is provided for changing and/or setting the thermal and/or geometric symmetry/asymmetry of the refractive indices in the two waveguides.

Abstract: Digital optical switches (1) with asymmetrical wave guides (2, 3; 5, 6) and an electro-optically controllable adiabatic coupling in a central region (4) must have a degree of crosstalk suppression of better than 20 dB for use in transparent optical networks. With X or Y arrangements, the invention provides for this purpose a grid device (10) in the central region (4) which affects the wave guide's inherent modes as the main cause of the crosstalk, i.e. amplitude and phase matching of the wave guide's inherent modes at the output. The result of the solution of the invention takes the form of a "cascade" of two different physical effects, each of which, of at least 20 dB, contributes to the overall result crosstalk suppression of better than 40 dB.

Abstract: An arrangement for polarization control for an optical heterodyne or homodyne receiver wherein the state of polarization of the optical signal of the local oscillator of a heterodyne or homodyne receiver and the optical signal supplied to the receiver can be transformed so that both signals can be adjusted to the same identical state of polarization. A phase modulator PM1 and a following polarization converter PK1 are arranged onto an optical waveguide WL1 which receives at an input e.sub.1 an optical wave from a subscriber and another polarization converter PK2 and a following phase modulator PM2 are arranged onto another optical waveguide WL2 which has an input e.sub.2 for coupling in the local oscillator signal. The arrangement can be controlled such that the signals fed in have the same state of polarization at the output for superposition and IF generation.

Abstract: Apparatus for continuous reset-free polarization and phase control which includes an optical strip waveguide 10 in which two waves TE and TM mode are polarized orthogonally relative to each other and have mutually different propagation constants .beta..sub.1 and .beta..sub.2 and includes a plurality of N=4m equidistant electrodes (E.sub.i, where i=1, 2 . . . N) which are mounted successively along the strip waveguide 10 and where m is a whole number between 5 and 10 and wherein each electrode E.sub.i receives a voltageU.sub.i =U.sub.0 sin (.eta.+(i-1).multidot..pi..multidot..LAMBDA..sub.0 /2.multidot..LAMBDA..sub.1) with i=1, 2, . . . Nwherein .LAMBDA..sub.0 is the geometrical length fixed by four electrodes and .LAMBDA..sub.1 is the length defined by the operating wavelength .LAMBDA..sub.1 and .eta. is a variable control quantity between and 0 and 2.pi. and U.sub.0 is a variable maximum voltage.