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RF frequency multiplexed fiber optic data bus

  • US 4,726,644 A
  • Filed: 07/08/1985
  • Issued: 02/23/1988
  • Est. Priority Date: 07/08/1985
  • Status: Expired due to Fees
First Claim
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1. A fiber optic data bus for multiplexing, transmitting, and demultiplexing a plurality of input RF signals as a corresponding plurality of output RF signals comprising:

  • a plurality of modulated light sources, each having an input adapted to receive a respective one of a plurality of input electrical RF signals each at a different RF carrier frequency wherein each modulated light source provides in response to a respective one of said input RF signals at an output a corresponding intensity modulated optical signal;

    signal collection means for combining said plurality of intensity modulated optical signals into a combined optical signal, said signal collection means comprising an input star coupler having an output and a plurality of inputs with each input of said input star coupler connected to a respective output of said plurality of modulated light sources;

    conducting means conncted to said signal collection means for conducting said combined optical signal, said conducting means comprising an optical fiber having a pair of ends with one end connected to said input star coupler output;

    signal distribution means connected to said conducting means for output distribution of said combined optical signal, said signal distribution means comprising an output star coupler having an input and a plurality of outputs with said input of said output star coupler connected to the other end of said optical fiber;

    a plurality of optical bandpass filters each having an input and an output, each optical bandpass filter input connected to a different output of said output star coupler, said optical bandpass filter comprising;

    a segment of multimode optical fiber of a predetermined length, L,;

    an input mirror on one end of said fiber segment;

    means for directing intensity modulated light into said fiber segment; and

    said fiber segment having a length substantially equal to half the wavelength of the modulation frequency in said fiber segment, with said fiber segment functioning as a resonant cavity and filtered output light exiting through said output mirror;

    a plurality of optical detectors each having an input and an output, each optical detector input connected to a different optical bandpass filter output; and

    wherein each of said optical filters extracts a predetermined portion of the distributed combined optical signal as an output optical signal which has a frequency corresponding to the modulation frequency of a respective one of said input RF signals and wherein each one of said optical detectors converts a respective output optical signal to an output electrical RF signal.

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