Abstract: A stabilization of the frequency spacing between the carrier frequency channels of the individual transmitters and the elimination of the risk of the channel crosstalk is obtained for an arbitrarily large number of transmitters in a coherent optical multi-channel arrangement which has a plurality of transmitters arranged in a group, a single coherent optical heterodyne arrangement for heterodyning a portion of the output of each of the transmitters with respective reference frequency lines and a control arrangement for controlling the channel carrier frequency of each of the transmitters by utilizing the heterodyne signal.

Abstract: For reducing power fluctuations of spectral lines of a comb generator having an annularly closed waveguide, a coupler for coupling light from a separate light source into the waveguide and out of the waveguide and also a sideband modulator, the light circulating in the waveguide can be either separately modulated or the sideband modulator can be operated to have only sidebands of the same operational sign of a frequency shift or with an amount being selected according to a particular arrangement, or can have both positive and negative frequency shifts with the amount being selected by a different formula or the length of the annularly closed waveguide can be dimensioned so that the size of the round-trip time of the light circulating in the waveguide is longer than the defined coherent time of the reference laser light. It is also possible to incorporate various combinations of these alternative ways of reducing the power fluctation.

Abstract: An apparatus for generating optical waves which are polarized orthogonally relative to each other from an incoming optical wave for enabling polarization-independent, optical superheterodyne reception has an integrated optical Mach-Zender interferometer which is preceded by an integrated optical directional coupler or by a waveguide fork and is followed by an integrated optical directional coupler.

Abstract: An apparatus for generating an FSK-modulated optical signal has an optical two-filter FSK super-heterodyne receiver. The optical signal has two different polarization conditions that are orthogonal to one another. Due to the two-filter receiver and orthogonal conditions, polarization-independent reception is possible. Conversion of the polarized, optical signal into the optical signal having the orthogonal polarization conditions is accomplished by a switching device. Each condition has a corresponding bit status of a data signal. The data signal effectively controls the polarizatiion of the optical signal. Hence, the frequency boost can be freely selected while maintaining excellent bandwidth characteristics and optimum sensitivity.

Abstract: An external optical resonator for a semiconductor laser is composed of an optical directional coupler which can be formed as an integrated optical coupler with a short structural length that enables a free spectral range in the order of 100 GHz and enables the resonator and the system fiber to be coupled to the same end face of the laser. The resonator structure includes two optical waveguides with feedback means applied on the end faces of one of the waveguides and the other waveguide having one end face coupled to receive the output of the laser and the other end face of the other waveguide being coupled to the system fiber. The arrangement is particularly useful for tunable semiconductor lasers, particularly for heterodyne reception.

Abstract: A method for generating an FSK-modulated optical signal with an optical two-filter FSK super-heterodyne receiver. The optical signal has two different polarization conditions that are orthogonal to one another. Due to orthogonal conditions, polarization-independent reception is possible. Synchronized polarization shifting occurs to generate a polarized modulated optical signal having alternating orthogonal polarization conditions. A delay stage for delaying the switching signal by one-half a clock period ensures accurate synchronization. The frequency shift of the FSK-modulated signal can be freely selected while maintaining excellent bandwidth characteristics and optimum sensitivity.

Abstract: An arrangement has at least one, and preferably two, optical waveguides integrated on a substrate of electro-optical material, has at least one first electrode for each of the waveguides being applied on the substrate and separated from the waveguide and substrate by an insulating layer and has at least one second electrode for each of the waveguides. The second electrodes are connected to a constant voltage source, while the first electrodes are connected to a modulating voltage source. The constant voltage source applied to the secondary electrodes and the position of these electrodes relative to the waveguides determines an operating point for modulating light in the waveguides.

Abstract: The invention relates to a process of dispersing oil-soluble photographic additives having a silver-halide base for information recording materials.According to the invention, compounds of the following general formula: ##STR1## are used as auxiliary dispersing agents. The symbolsR represents hydrogen, alkyl with 1 to 8 C atoms,M represents hydrogen, alkali metal, ammonium, andX represents OR or SO.sub.3 M.