Agilent Technologies, Inc.

Raffaele Girardi

Francesco Cisternino

Andrea De Marchi

Stefania Roemisch

Riccardo Calvani

Emilio Riccardi

This invention concerns a method of and a device for optical demultiplexing that are based on the four wave mixing between the signals to be demultiplexed and pump signals. The two signals are fed into a polarization maintaining fiber ( ), which divides them into two components with orthogonal polarization, separated in time; and the four wave mixing is performed separately on the two components, thereby originating two separate signals that are polarization-rotated and re-combined. (FIG. ).

Method of and a device for polarization-independent optical demultiplexing

The circuit includes an electro-optical mixer, such as an electro-optical Mach-Zehnder modulator, with non-linear behavior. The modulator receives as input an optical signal (P,) at the frequency to be divided, in addition to an electric signal (e,) at a given frequency, usually corresponding to the frequency deriving from such division. The output optical signal (P,) from modulator exhibits a modulation spectrum containing the frequency difference between the frequency to be divided and at least one harmonic of the frequency of the above electric signal. After having been converted into an electric signal (e,), the output signal of the mixer is subjected to a filtering action to extract the above frequency difference component. This latter one is then used both as electrical signal (e,) for the mixing, and as output signal from the divider (e,). The preferred application is to OTDM systems, to extract a synchronism signal as tributary signal frequency.

Opto-electronic frequency divider circuit and method of operating same

The circuit includes an electro-optical mixer, such as an electro-optical Mach-Zehnder modulator (,), with non-linear behaviour. The modulator (,) receives as input an optical signal (P,) at the frequency to be divided, in addition to an electric signal (e,) at a given frequency, usually corresponding to the frequency deriving from such division. The output optical signal (P,) from modulator (,) exhibits a modulation spectrum containing the frequency difference between the frequency to be divided and at least one harmonic of the frequency of the above electric signal. After having been converted into an electric signal (e,), the output signal of the mixer is subjected to a filtering action (,) to extract the above frequency difference component. This latter one is then used both as electrical signal (e,) for the mixing, and as output signal from the divider (e,). The preferred application is to OTDM systems, to extract a synchronism signal at tributary signal frequency.

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Mondovi, Italy

Raffaele Girardi