Erbium-ytterbium miniaturized laser devices for optical communications

In this work we review the most recent results obtained by our group on miniaturized diode-pumped Er-Yb:glass lasers of potential interest for optical communication applications. In single frequency operation we achieved output powers larger than 25 mW using a 200-mu m length microchip laser and in excess of 100 mW, with a large tunability over the wavelength range between 1528 nm and 1564 nm, using a 5-mm length resonator containing an intracavity 50-mu m thick Polarcor etalon. The Er-Yb microlaser has been locked and frequency stabilized at a level better than 1x10(-9) to C2H2 and (C2H2)-C-13 absorption lines in the wavelength range from 1530 ma to 1550 nm, to built a narrow-linewidth absolute frequency reference in this spectral region suitable for WDM applications. A 30-dB suppression of the intensity noise peak at the relaxation oscillation frequency has been obtained and a relative intensity noise level of less than -160 dB/Hz at frequencies higher than 20 MHz is expected. In pulsed operation regime, picosecond pulse trains with repetition rate up to 10 GHz have been generated by either the FM mode-locking and a novel technique based on frequency modulation operation of the laser followed by external spectral filtering of the optical field, able to produce transform-limited single and dual-wavelength pulse trains particularly suitable for soliton transmission.