Series in Quantum Electronics
Henry Baltes, Peter Günter, Ursula Keller,
Fritz K. Kneubühl †, Walter Lukosz,
Hans Melchior, Markus W. Sigrist
Andreas Stefan Rutz
GaInNAs SESAMs and VECSELs
at 1.3 and 1.5 μm wavelength.
1st edition 2008. 164 pages; € 64,00.
ISBN 3-86628-203-6 and 978-3-86628-203-2
Modelocked solid-state lasers and vertical-external-cavity surface emitting lasers in the wavelength region of 1.3 to 1.5 µm are an interesting topic for several applications from telecommunication to frequency-doubled sources for video projection systems. GaInNAs is a promising candidate as an active and passive semiconductor material in this wavelength range. An understanding of the material properties, as well as a stable growth process forms the foundation for a commercial application of such dilute nitride semiconductors in future. This thesis discusses the properties and fabrication of GaInNAs material with different perspective. In a first step, GaInNAs-based semiconductor saturable absorber mirrors (SESAMs) for modelocking of solid-state lasers at 1.5 µm wavelength are developed. On the basis of these devices, we developed SESAMs for an Er:Yb:glass laser (ERGO) operating at 1534 nm. The final structure showed a modulation depth of 0.39% and a saturation fluence of 20 µJ/cm2 in an antiresonant structure, which is an exceptionally low value for quantum well devices. Due to the large number of growth-defects introduced during nitrogen incorporation, a bleaching recovery time of 18 ps was attained. Using this SESAM, pulses of 5 ps duration at a repetition rate of 61 MHz were obtained from the laser. As a second step, a GaInNAs-based vertical external-cavity laser (VECSEL) was developed. The growth temperature, V/III BEP ratio, plasma cell operating conditions as well as the thermal annealing parameters were optimized. Using such optimized material, we fabricated a GaInNAs VECSEL, generating 600 mW continuous wave output. Modelocked operation was also demonstrated at a repetition rate of 6 GHz and a pulse duration of 18.7 ps using a GaInNAs SESAM specifically developed for this VECSEL. As the processes limiting the radiative efficiency in GaInNAs are still largely unknown, photoinduced current transient spectroscopy (PICTS) was used for the characterization of deep-level defects in SESAMs and active structures. The results indicate that the method works well in the presented setup, allowing for measurements of single quantum wells with high resolution.
About the author:
Andreas Rutz received his diploma in materials science from the Swiss Federal Institute of Technology in Zurich, where he joined the Institute of Quantum Electronics in April 2004. His research focused on the development of GaInNAs-based passive and active components for mode-locked lasers at 1.3 und 1.5 µm wavelength using molecular beam epitaxy.
Keywords: GaInNAs, Molecular Beam Epitaxy (MBE), passive modelocking, VECSELs, Growth process development, optically pumped semiconductor lasers, dilute nitrides
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