Generación de frecuencias de referencia para la calibración de sistemas WDM en comunicaciones ópticas

Resum

This thesis deals with the generation of reference frequencies in the wavelength range between 1250 and 1650 nm suitable for the calibration of optical spectrum analyzers and wavelength meters used in the characterization of dense wa1,elengthdivision multiplexed (D WD M) systems. The reference frequencies have been generated using two clearly distinct methods. On one side, we have demosntrated active stabilization of tunable laser diodes in absorption lines of several reference gas samples: acetylene 12C2H2 (far the wavelength region around 1550 nm), water vapo·ur H2 0 (in the spectral region of 1400 nm) and methane CH4 (in the spectral region of 1300 nm). The results obtained depend on the uncertainty in the frequency of the reference absorption line, reaching the best results w-ith the cell fabricated and calibrated at NIST. On the other hand, to obtain references in the spectral regions where these gases do not present clear absorption lines, we have used Jrequency conversion techniques based on four-wave mixing in optical fibers and semiconductor optical amplifiers. Finally, we have tested the suitability of hollow fibers filled with methane for the development of reference gas cells. Jor field instruments in the region of 1300 nm. As a result of this thesis, the wavelength measurement scale in the Department of Metrology ojthe Applied Physics Institute (CSIC) in the spectral region between 1300 nm and 1600 nm has been established in ± 1. 5 pm with direct traceability to NIST.