Signal converter, optical transmitter and optical fiber transmission system

A signal converter for receiving a multichannel video signal and converting the video signal into a microwave signal, the frequency of which has been modulated with the video signal,

• the signal converter comprising:
• a laser light source;
• modulation means for modulating the frequency of output light of the laser light source with the multichannel video signal and modulating the intensity of the output light with the microwave signal;
• and
• a light receiver for receiving the output light modulated by the modulation means and for outputting the microwave signal, the frequency of which has been modulated with the multichannel video signal.

A multichanneled optical fiber transmission system comprising:

• the optical transmitter of the type recited in claim 26;
• an optical fiber amplifier for amplifying an optical signal output from the optical transmitter;
• an optical coupler for branching the amplified optical signal;
• an optical fiber for transmitting the branched optical signal;
• and
• a light receiver for converting the optical signal, transmitted through the optical fiber, into a multichannel video signal.

An optical signal converter comprising:

• an optical output limiter for receiving an optical signal having had the intensity thereof modulated with a sub-carrier having had the frequency thereof modulated with a multichannel signal and for outputting light while the level of the waveform of the optical signal is at a predetermined level or higher, thereby generating a first optical pulse train;
• an optical delay circuit for delaying the first optical pulse train to generate a second optical pulse train;
• and
• an optical logic element for outputting a third optical pulse train having an optical pulse interval proportional to the multichannel signal based on the first and the second optical pulse trains.

An optical fiber transmission system comprising:

• an optical transmitter for generating an optical signal, the intensity of which has been modulated with a sub-carrier having had the frequency thereof modulated with a multichannel signal;
• an optical fiber for transmission for transmitting the optical signal;
• and
• an optical receiver for receiving the optical signal through the optical fiber for transmission, and demodulating the multichannel signal from the optical signal,
• wherein the optical receiver includes:
• an optical signal converter for outputting an optical pulse train based on the optical signal, the optical pulse interval of the train being proportional to the multichannel signal;
• and
• a photoelectric transducing section for receiving the optical pulse train and converting the train into an electrical signal.

A multichanneled optical fiber transmission system comprising:

• an optical transmitter for generating an optical signal, the intensity of which has been modulated with a sub-carrier having had the frequency thereof modulated with a multichannel signal;
• an optical fiber amplifier for amplifying the optical signal;
• an optical coupler for branching the optical signal into a plurality of luminous fluxes;
• an optical fiber for transmission for transmitting the branched optical signal;
• and
• an optical receiver for receiving the optical signal through the optical fiber for transmission, and demodulating the multichannel signal from the optical signal,
• wherein the optical receiver includes:
• an optical signal converter for outputting an optical pulse train based on the optical signal, the optical pulse interval of the optical pulse train being proportional to the multichannel signal;
• and
• a photoelectric transducing section for receiving the optical pulse train and converting the train into an electrical signal.