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Optical frequency shifter and transmission system

  • US 6,259,836 B1
  • Filed: 05/14/1998
  • Issued: 07/10/2001
  • Est. Priority Date: 05/14/1998
  • Status: Expired due to Fees
First Claim
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1. A multiple optical carrier generator comprising a cascaded chain of N optical frequency shifters, the chain of optical frequency shifters including a final optical frequency shifter, each optical frequency shifter comprising:

  • an input light guide;

    a first set of modulators in parallel and each connected to receive light from the input light guide via a first splitter;

    an output light guide connected to receive light from the first set of modulators through an optical combiner, each output light guide other than the output light guide from the final optical frequency shifter forming an input light guide to a subsequent optical frequency shifter in the chain of optical frequency shifters;

    plural voltage sources, each modulator of the first set of modulators being connected to receive a modulating voltage from a respective one of the voltage sources;

    the voltage sources having output voltages characterized such that modulated light appearing on the output light guide of each optical frequency shifter is translated in frequency by a frequency ω

    1 from light input to the input light guide of the optical frequency shifter, whereby the chain of optical frequency shifters produces a set of N multiple optical carriers ω

    0+iω

    1 where i=1 . . . N;

    and the multiple optical carrier generator further comprising;

    a respective one of a set of compensating amplifiers connected at the output of each optical frequency shifter so as to maintain a nearly constant amplitude of light in the chain of optical frequency shifters; and

    optical taps at each amplifier to provide an output of each optical carrier for use in transmitters and receivers of a wavelength division multiplexed optical communication system.

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