Modified LINC transmitter using efficient parallel amplification scheme

Abstract

and the curve of the laser temperature tracking are shown in Figure 3(b). CONCLUSIONSWe have shown that a CW-clock transfer is possible over several 100-meters long links using affordable and commercially available telecom-grade optical and RF components achieving an extremely low-added timing jitter and high long-term stability. Group-delay variations of the RF signal in the presented clock-distribution system are compensated by the laser-wavelength tuning and the exploitation of the chromatic dispersion of the optical fibers in the forward and backward direction. Besides our fully compensated and filtered clock-distribution scheme, we believe that our outstanding results are also due to the excellentquality, mass-produced electrical and optical components that became available recently: (1) microwave and optoelectronic components: monolithic gain blocks with stable gain, monolithic mixers with excellent balance and offset used as phase detectors, integrated PIN-FET modules with repeatable performance and (2) mass-produced optical fiber to very tight specifications including PMD. Although PMD effects were not compensated in our system, we experimentally confirmed that all fiber tolerances including PMD are tight enough to allow almost perfect tracking in an inexpensive fiber pair, a much cheaper solution than using a single fiber together with fiber couplers, circulators and/or Faraday mirrors. ACKNOWLEDGMENTSThis work was supported by Instrumentation Technologies d.d., Slovenia, Sincrotrone Trieste S.C.p.A., Italy, and Ministry of Higher Education, Science and Technology of the Republic of Slovenia under the research program P2-0246. The authors are grateful to V. Poucki and M. Predonzani for help with long-term measurements and data acquisition.