System of optical telephony

Claim 1

A system of optical telephony which is capable of putting N subscribers in communication with one another, said arrangement including: N telephone sets ascribed respectively to the N subscribers, each set including a microphone into which a subscriber speaks and which delivers in return an electric send signal, an earphone which receives an electric receive signal and which delivers in return an acoustic signal received by the subscriber, a laser generator which is capable of delivering a send light wave, means for modulating the amplitude of the send light wave by the frequency of said electric send signal, and a photoelectric receiver which receives a receive light wave and is capable of delivering in return said electric receive signal at whose frequency the amplitude of said receive light wave is modulated; N pairs of optical fibres connected to respective ones of the telephone sets of the N subscribers, each pair including a send optical fibre and a receive optical fibre, a first end of the send optical fibre receiving said send light wave, the receiver optical fibre transmitting said receive light wave and delivering it at the second end of the send optical fibre to said photoelectric receiver; and an interconnection centre to which said second ends of the N pairs of optical fibres are connected, wherein said interconnection centre is a volume whose surface is formed at least partially by the surfaces of said second ends of the N pairs of optical fibres; and wherein different optical frequencies F 1 . . . F N are ascribed to respective subscribers, modulation frequencies F 1 . . . F N which are different from one another being ascribed to respective subscribers, the modulation frequencies being lower than the optical frequencies; subscriber p's laser generator delivers a send light wave of frequency F p ascribed to subscriber p; subscriber p's telephone set further includes: means for modulating the amplitude of said send light wave of frequency F p by the modulation frequency f n ascribed to subscriber n; N-1 optical filters capable of passing only frequencies F 1 . . . , F p-1 , F p+1 . . . F N respectively, the input of each of these optical filters being disposed to receive said receive light waves; N-1 selective electro-optical detectors which receive the light energy that emerges from respective ones of the N-1 optical filters, these detectors delivering an electric signal only if the amplitude of the light energy they receive is modulated at the frequency f p ; means which receive the electric signals delivered by said selective detectors, said means being capable of informing subscriber p of the order n of the filter of frequency F n whose output radiation is causing the emission of an electric signal from the selective detector which receives said output radiation; and an optical conductor one of whose ends is disposed on the input surface of said photoelectric receiver and means for disposing the other end of said optical conductor on the output of said optical filter of frequency F n .

Claim 2

A system of optical telephony which is capable of putting N subscribers in communication with one another, said arrangement including: N telephone sets ascribed respectively to the N subscribers, each set including a microphone into which a subscriber speaks and which delivers in return an electric send signal, an earphone which receives an electric receive signal and which delivers in return an acoustic signal received by the subscriber, a laser generator which is capable of delivering a send light wave, means for modulating the amplitude of the send light wave by the frequency of said electric send signal, and a photoelectric receiver which receives a receive light wave and is capable of delivering in return said electric receive signal at whose frequency the amplitude of said receive light wave is modulated; N pairs of optical fibres connected to respective ones of the telephone sets of the N subscribers, each pair including a send optical fibre and a receive optical fibre, a first end of the send optical fibre receiving said send light wave, the receiver optical fibre transmitting said receive light wave and delivering it at the second end of the send optical fibre to said photoelectric receiver; and an interconnection centre to which said second ends of the N pairs of optical fibres are connected, wherein said interconnection centre is a volume whose surface is formed at least partially by the surfaces of said second ends of the N pairs of optical fibres; and wherein different optical frequencies F 1 . . . F N are ascribed to respective subscribers, modulation frequencies F 1 . . . F N which are different from one another being ascribed to respective subscribers, the modulation frequencies being lower than the optical frequencies; subscriber p's laser generator delivers a send light wave of frequency F p ascribed to subscriber p; subscriber p's telephone set further includes: means for modulating the amplitude of said send light wave of frequency F p by the modulation frequency f n ascribed to subscriber n; N-1 optical filters capable of passing only frequencies F 1 . . . , F p-1 , F p+1 . . . F N respectively, the input of each of these optical filters being disposed to receive said receive light waves; N-1 selective electro-optical detectors which receive the light energy that emerges from respective ones of the N-1 optical filters, these detectors delivering an electric signal only if the amplitude of the light energy they receive is modulated at the frequency f p ; means which receive the electric signals delivered by said selective detectors, said means being capable of informing subscriber p of the order n of the filter of frequency F n whose output radiation is causing the emission of an electric signal from the selective detector which receives said output radiation; and an optical conductor one of whose ends is disposed on the input surface of said photoelectric receiver and means for disposing the other end of said optical conductor on the output of said optical filter of frequency F n .