Tellurium (Te)-doping of self-catalyzed GaAs nanowires (NWs) grown by molecular beam epitaxy is reported. The effect of Te-doping on the morphological and crystal structure of the NWs is investigated by scanning electron microscopy and high-resolution transmission electron microscopy. The study reveals that the lateral growth rate increases and axial growth rate decreases with increasing Te doping level. The changes in the NW morphology can be reverted to some extent by changing the growth temperature. At high doping levels, formation of twinning superlattice is observed alongside with the {111}-facetted sidewalls. Finally, the incorporation of Te is confirmed by Raman spectroscopy. V

We demonstrate a compact core-pumped 2 microm Tm(3+), Ho(3+)- doped all-fiber laser passively Q-switched with an antimony-based saturable absorber. The 20 ns pulses are the shortest Q-switched pulses from a fiber laser operating beyond 1850 nm and were produced at a repetition rate of 57 kHz and pulse energy of 15 microJ using a short-length (4 ns) cavity. The large absorber modulation depth of approximately 70% together with transient gain compression is shown to provide an efficient mechanism for Q-switched pulse shortening.

No abstract

We report on a passively mode-locked optically pumped GaSb-based semiconductor disk laser producing stable picosecond optical pulses at a 1.95 μm wavelength. The gain mirror was comprised of a 15 quantum well InGaSb/GaSb structure. A fast semiconductor saturable absorber mirror with three InGaSb/GaSb quantum wells was used to attain self-starting mode-locked operation at a fundamental repetition rate of 881.2 MHz. The laser produced pulses with 30 pJ energy and a duration of 1.1 ps within a factor of 2 of the Fourier limit.

A technique for stabilizing the repetition frequency of a passively Q-switched laser is presented using an optically driven surface-normal semiconductor modulator. A method is capable of significant reduction of the timing jitter in a passively Q-switched laser by optical triggering the saturable absorber semiconductor reflector. The experimental demonstration using passively Q-switched ytterbium-doped fiber laser shows the jitter reduction by factor of 1.66??10(3) from 50 mus down to 30 ns.