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Frequency Multiplex System Using Injection Locking of Multiple Laser Diodes.

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An optical frequency division multiplex system including a transmitter, a receiver, and a transmission path connecting the transmitter to the receiver. In the transmitter a master laser is operated to produce a central peak at an optical frequency f sub o with side peaks separated by an amount delta f running to both sides of the central peak. The master laser output goes through an optical isolator to an optical coupler where it is split up into N1 beams. Each optical output from the coupler is then positioned to be coupled into N slave lasers. Each slave laser is tuned to approximately coincide with one of the side peaks thus producing a single output frequency of f sub o or - n delta f from each slave laser diode. Electrical modulating signals for each of N information channels are applied separately to modulate the phase of each of the slave laser outputs. The outputs of the slave lasers are then recombined in a NX1 optical coupler, the outputs of which is transmitted over a single-mode fiber linking the transmitter to the receiver. One of the outputs of the 1XN1 coupler is transmitted to the receiver over a second single-mode fiber. At the receiver, the master laser carrier is split into N spatial components by a 1XN coupler. There are then filtered and amplified by a second group of N slave lasers. The output from this second unmodulated group of slave lasers is combined with the combined outputs from the modulated slave lasers in an array of 2X1 optical couplers. Finally, the light signals emerging from the couplers are converted to electrical signals for the N information channels by an array of photodetectors. Patents.

Subject Categories:

  • Non-Radio Communications
  • Lasers and Masers

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