| 摘要 |
<p>Apparatus for recovering clock pulses of wavelength division multiplexed optical signals in a return-to-zero format passed therethrough. The apparatus comprises an optically-pumped laser cavity (3, 9) defining a cavity length and comprising a nonlinear medium (3) pumped at a wavelength selected to give efficient parametric amplification within said medium. The cavity length corresponds to an integer multiple of bit periods of at least one of the multiplexed optical signals. The optical signals co-propagate through the medium with the pump radiation. The apparatus further comprises an optical path for recirculating a proportion of the output from the laser cavity back through the laser cavity. In this way, idler waves are generated symmetrically about the pump wavelength by four-wave mixing with the at least one of the multiplexed optical signals and recirculated through the laser cavity to be amplified by parametric amplification in order to recover wavelength division multiplexed clock pulses. An additional amplifier may be provided to compensate cavity losses.</p> |
