Pulsed and Polarization-stabilized GaSb Disk Lasers for 2.0-2.35 μm Wavelength Range
Alanko, Jukka-Pekka (2011)
Alanko, Jukka-Pekka
2011
Teknis-luonnontieteellinen koulutusohjelma
Luonnontieteiden ja ympäristötekniikan tiedekunta - Faculty of Science and Environmental Engineering
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Hyväksymispäivämäärä
2011-06-08
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-2011062214740
https://urn.fi/URN:NBN:fi:tty-2011062214740
Tiivistelmä
Optically-pumped semiconductor disk lasers are light sources that offer an outstanding variety of methods in controlling the emission. They are capable of producing laser radiation in power levels of tens of watts with excellent, near-diffraction limited beam, and the fundamental emission wavelength can be controlled with band gap engineering of the semiconductor material. Moreover, the laser architecture gives the opportunity to generate high-brightness visible light via nonlinear frequency-conversion and to produce ultra-short pulses through mode-locking. Due to the high-quality output beam and the flexibility in the design, this laser type is a truly interesting alternative in finding illumination for several applications.
The focus of this thesis is on research and development of semiconductor disk lasers based on gallium-antimonide (GaSb) material system. Two different kind of semiconductor lasers emitting in the near-infrared were built and characterized. It was shown that a novel grating mirror fabricated out of germanium (Ge) can be used as a partially transparent cavity mirror in a semiconductor disk laser. The polarization-selective nature of the grating resulted in controllability of the polarization direction in laser output, which is a crucial property of lasers in several applications. This indicates that small-size, easily processable low-cost gratings could be used to replace traditional, thick dielectric laser cavity mirrors in certain applications. With an enhanced design, the reflectance spectrum of the grating can be tailored to result in distinguished performance.
The other part of this work concerned the first GaSb disk laser producing femtosecond pulses. The laser was passively mode-locked with a semiconductor saturable absorber mirror. For ultra-short pulse duration measurement, an interferometric autocorrelator based on two-photon absorption was built and successfully used. In the mid-infrared wavelengths such short pulse lasers are applicable for optical clocking or as seeders for optical amplifiers and supercontinuum lasers. /Kir11
The focus of this thesis is on research and development of semiconductor disk lasers based on gallium-antimonide (GaSb) material system. Two different kind of semiconductor lasers emitting in the near-infrared were built and characterized. It was shown that a novel grating mirror fabricated out of germanium (Ge) can be used as a partially transparent cavity mirror in a semiconductor disk laser. The polarization-selective nature of the grating resulted in controllability of the polarization direction in laser output, which is a crucial property of lasers in several applications. This indicates that small-size, easily processable low-cost gratings could be used to replace traditional, thick dielectric laser cavity mirrors in certain applications. With an enhanced design, the reflectance spectrum of the grating can be tailored to result in distinguished performance.
The other part of this work concerned the first GaSb disk laser producing femtosecond pulses. The laser was passively mode-locked with a semiconductor saturable absorber mirror. For ultra-short pulse duration measurement, an interferometric autocorrelator based on two-photon absorption was built and successfully used. In the mid-infrared wavelengths such short pulse lasers are applicable for optical clocking or as seeders for optical amplifiers and supercontinuum lasers. /Kir11