Abstract: For frequency stabilization of a WDM multiplexer/demultiplexer with an optical phased array, a control signal with reference to which the WDM multiplexer/demultiplexer temperature is set is acquired by subtraction of the two opto-electrically converted output reference signals of two reference signal channels of the single-channel side of the optical phased array having filter curves intersect at a frequency corresponding to the frequency of an input reference signal supplied at the multiplex side.

Abstract: In a circuit arrangement for optical frequency conversion, having a switchable input filter arrangement with a wavelength channel filter of a wavelength multiplexer/demultiplexer which is formed using a number of such channel filters, which filter can be connected via a 1:n fiber switch to an input fiber and is passed through by the input signal in the multiplex operating direction, a frequency converter which is passed through in opposite directions by the input signal and a pump laser signal, and an output filter, the output filter is formed by a wavelength channel filter of the wavelength multiplexer/demultiplexer, which filter is passed through by the output signal in the demultiplex operating direction and is connected on the output side to the output fiber.