TUTCRIS - Tampereen teknillinen yliopisto


Optical Pulse Generation with Semiconductor Disk Lasers



KustantajaTampere University of Technology
ISBN (elektroninen)978-952-15-2882-8
ISBN (painettu)978-952-15-2868-2
TilaJulkaistu - 21 kesäkuuta 2012
OKM-julkaisutyyppiG5 Artikkeliväitöskirja


NimiTampere University of Technology. Publication
KustantajaTampere University of Technology
ISSN (painettu)1459-2045


Optical pulses are used as bits to transmit information. Controlled pulse generation is required for error-free communication and data processing. Semiconductor disk lasers (SDLs) are compact light sources that have shown potential for inexpensively generating intense but focusable ultrashort light pulses of a chosen color at gigahertz repetition rates. In this thesis, the generation of light pulses with SDLs is studied. Different methods for initiating pulsed operation are reviewed. A state-of-the-art high-power picoseconds pulse source emitting in the 1.55-μm telecommunications band is demonstrated by employing wafer fusion technology and advanced heat management in an SDL pulsed with a dilute nitride semiconductor saturable absorber mirror (SESAM). A simple way to generate picosecond pulses from an SDL by feeding frequency-shifted light back to the gain element of the laser is presented. The dominant way to generate pulses from SDLs, using a SESAM to organize the phases of the lasing cavity modes, is studied in detail. Models for pulse shaping in such passively mode-locked SDLs are reviewed. Stable mode locking (ML) at a very low saturation of absorption, relevant for SDLs pursuing high pulse repetition rates, is demonstrated and qualitatively explained. The regime of harmonic ML where multiple pulses circulate in the SDL cavity is reported and investigated both experimentally and numerically. Saturation and fast recovery of the gain are identified as being responsible for the strong ordering of pulses and for the changes in pulse characteristics observed between states with different numbers of pulses in the cavity. Hysteresis in the properties of the optical output is observed and controlled by tailoring the SDL gain element design. The presented results provide a means to precisely manipulate pulse characteristics in SDLs, paving the way for flexible high-speed data transfer and processing.

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