COHERENT FREQUENCY-DOMAIN REFLECTOMETRY FOR CHARACTERIZATION OF SINGLE-MODE INTEGRATED-OPTICAL WAVE-GUIDES

Based on the principles of optical frequency domain reflectometry (OFDR) a highly resolving and sensitive technique is developed suitable for detecting, localizing, and quantifying weakly reflecting irregularities in single-mode optical waveguides. A DFB-laser diode at lambda0 congruent-to 1.3 mum tuned within a range of DELTAlambda congruent-to 6 nm and DELTAnu congruent-to 1 THz, respectively, is used as a source in the experimental arrangement. Employing an auxiliary interferometer the tuning need not be linear in time, in contrast to early implementations. At present, with waveguide structures on InP under test, we get a spatial resolution of 50 mum and a dynamic range of about 60 dB. These data surpass OFDR-results published so far. Prospects of closing the gap to coherence-domain reflectometric results and specific advantages make OFDR to be a promising technique.