We report the observation of whispering-gallery-mode lasers based on Er(3+) -doped ZBLAN microspheres coupled with half-tapered and tapered optical fibers. A multimode lasing effect is observed at 1.56mu when the taper diameters are properly adjusted so that their fundamental propagation constants match those of the resonant modes of interest. Overlap between the pump and the laser geometrical modes is optimized by pumping at 1.48mu .

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We report on the 1.5 µm laser emission from InAs quantum dots (QDs) grown on a InP(311)B substrate. The control of the optical wavelength emission is obtained by a two-step modified growth procedure, called the 'double cap' procedure. This enables us to obtain a 1.55 µm optical emission from InAs/InP(311)B QDs, with a narrow height dispersion. Laser emission on a six-stacked InAs QD layer sample has been demonstrated with optical excitation at room temperature. Lasing has been obtained on an excited state, for a low optical excitation density of 10 kW cm −2 . This shows that a QD laser could emit at the optical telecommunication wavelength.