Series in Quantum Electronics
edited by
Henry Baltes, Peter Günter, Ursula Keller,
Fritz K. Kneubühl †, Walter Lukosz,
Hans Melchior, Markus W. Sigrist

Vol. 43

Valeria Liverini

From Passive to Active Devices:
GaInNAs as Absorber and Emitter for 1.3 μm Lasers

1st edition 2007. XXII, 128 pages; € 64,00. ISBN 3-86628-159-5


This thesis deals with the development of GaInNAs as the absorber for semiconductor saturable absorber mirrors (SESAMs) and as the gain medium for vertical external-cavity surface-emitting lasers (VECSELs). The use of this quaternary alloy allows the development of such devices in the interesting near-infrared wavelength region of 1.3 μm, where cost-effective pulsed laser sources are needed for telecommunication applications, optical clocking of future generation processors and other applications such as laser displays and laser sources for biomedical use. The growth of GaInNAs was carried out by molecular beam epitaxy. The material worked very well as-grown and with mild post-growth annealing as a saturable absorber in SESAMs. Using these SESAMs, we achieved modelocking in the megahertz repetition rate region of Nd:YLF and Nd:YVO4 lasers, while the repetition rate was pushed up to 10 GHz with close to transform-limited pulses for the Nd:YVO4 laser. Careful optimizations of both the growth and post-growth annealing conditions were necessary to improve the GaInNAs PL efficiency to obtain material quality adequate for lasing. By studying the GaInNAs annealing-induced blueshift of the bandgap energy and its PL efficiency improvement, we could correlate these effects with nitrogen concentration and with the annealing parameters of time and temperature. We discovered that the nitrogen content in GaInNAs influences the total amount of blueshift but does not affect the improvement of the PL efficiency. GaInNAs quantum wells optimized for the gain region of the VECSELs were grown at a lower temperature than the ones used for the SESAMs and annealed in-situ at high temperature for a short time and at lower temperatures for a longer time. Finally, we developed GaInNAs VECSELs to obtain 1.3 μm lasers with sizes even more compact than the solid-state lasers presented above. We demonstrated optically pumped continuous wave (cw) VECSELs with output powers as high as 607 mW and an optical-to-optical efficiency of 10%, results comparable to the state-of-the-art. By using a GaInNAs SESAM in the external cavity of these VECSELs, we obtained for the first time self-starting cw modelocking of a 1.3 μm VECSEL. The average output power of the modelocked VECSEL was 57 mW in 18.7 ps pulses at a repetition rate of 6.1 GHz. Both the cw and modelocked lasers had close to diffraction-limited beam qualities


Valeria Liverini received her Bachelor of Science in Physics at the University of Texas, Austin in 1999 and her Master of Science in Electrical Engineering – Photonics at the University of California, San Diego in 2002. She joined the Institute of Quantum Electronics at the Swiss Federal Institute of Technology in Zurich (ETHZ) in 2003. Her research focused on the development by molecular beam epitaxy of GaInNAs semiconductor saturable absorber mirrors and vertical external-cavity surface-emitting lasers. Her work also included material and optical characterization of these devices and their design and testing.


Keywords: GaInNAs, dilute nitrides, molecular beam epitaxy (MBE), vertical external-cavity surface-emitting lasers (VECSELs), semiconductor saturable absorber mirrors (SESAMs), modelocking

Series in Quantum Electronics

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