|Book Series (74)||
|Biochemistry, molecular biology, gene technology||104|
|Domestic and nutritional science||39|
|Environmental research, ecology and landscape conservation||124|
|ISBN-13 (Hard Copy)||9783736997981|
|Book Series||Innovationen mit Mikrowellen und Licht. Forschungsberichte aus dem Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik|
|Place of Dissertation||TU Berlin|
|Keywords||spectral stabilization, DFB-BA lasers, diode laser systems, high order gratings, bi-directional eigenmode expansion, propagation modelling|
High-power distributed feedback broad area (DFB-BA) lasers are key components for pumping narrow absorption bands in solid-state lasers and for brightness scaling in direct diode laser systems via dense spectral beam combining. Today, the market for these lasers is dominated by DFB-BA lasers with low-order Bragg gratings that are integrated via buried overgrowth techniques.
A promising alternative are DFB-BA lasers with high order grat-ings that are directly etched into the p-side of the epitaxial layer structure, so that no interruption of the epitaxial growth process is required. Prior to this work, studies of such DFB-BA lasers were restricted to experimental proof-of-principal realizations. Further, adequate simulation tools were not available, as surface-etched gratings introduce a high refractive index contrast and can therefore not be calculated directly within the coupled mode theory (CMT).
Hence, this work treats the development of efficient high-bright-ness DFB-BA lasers and laser arrays with surface-etched gratings at 975 nm. The development of these lasers encompasses three steps: First, a design study of high-brightness Fabry-Pérot laser diodes that are suitable for the integration of surface-etched gratings. Second, the implementation of an adequate numerical model for the simulation of high-order surface-etched DFB grat-ings. Therefore, a simulation based on CMT is extended by bi-directional eigenmode expansion and propagation modelling. And third, a comprehensive experimental study of spectrally stabilized high-brightness DFB-BA lasers. Optimized DFB-BA lasers (L = 6 mm, W = 30 µm) operate with 56% peak conversion efficiency and achieve 5.8 W output power with a slow-axis beam parameter product ≤ 1.8 mm×mrad, and a linewidth ≤ 1.0 nm.