Abstract: A current supply is disclosed for frequency-proportional optical sensors, preferably fiber-optical sensors, having a constant amplitude modulated over time. The delay time of the modulation is kept constant as well in the current supply in order to increase the accuracy of measurement. A variable resistor that is connected in series with the LED or the semiconductor laser is used for this purpose. This resistor may for example be a photoresistor illuminated by a light source and the resistance value of this resistor is varied by an open-loop or closed-loop control circuit. The variable resistor may also be a resistor that is heated by its own current.

Abstract: A multi/demultiplexer is disclosed wherein the light-conducting fibers are cemented into a perforated plate made of a photolithographically etchable material, and their terminal faces are ground down and polished together with the surface of the perforated plate. To compensate for focusing differences, a plate of appropriately matched thickness is disposed between the transparent supporting block and the surface of the perforated plate.

Abstract: Channel separation of wavelength multi/demultiplexers using a grating structure in a planar multimode slab waveguide is improved by choosing the thickness of the slab waveguide to be greater than the input diameter at least in the area of the grating structure. The aperture of the radiation incident upon the grating structure is chosen to be correspondingly smaller than the input aperture.