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Subject: beam quality × WGL Institute: WIAS ×

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Now showing 1 - 2 of 2
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    Traveling wave analysis of non-thermal far-field blooming in high-power broad-area lasers
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2019) Zeghuzi, Anissa; Radziunas, Mindaugas; Wünsche, Hans-Jürgen; Koester, Jan-Philipp; Wenzel, Hans; Bandelow, Uwe; Knigge, Andrea
    With rising current the lateral far-field angle of high-power broad-area lasers widens (far-field blooming) which can be partly attributed to non-thermal effects due to carrier induced refractive index and gain changes that become the dominant mechanism under pulsed operation. To analyze the non-thermal contribution to far-field blooming we use a traveling wave based model that properly describes the injection of the current into and the diffusion of the carriers within the active region. Although no pre-assumptions regarding the modal composition of the field is made and filamentation is automatically accounted for, the highly dynamic time-dependent optical field distribution can be very well represented by only few modes of the corresponding stationary waveguide equation obtained by a temporal average of the carrier density and field intensity. The reduction of current spreading and spatial holeburning by selecting proper design parameters can substantially improve the beam quality of the laser.
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    Simulations and analysis of beam quality improvement in spatially modulated broad area edge-emitting devices
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2014) Radziunas, Mindaugas; Herrero, Ramon; Botey, Muriel; Staliunas, Kestutis
    We simulate and analyze how beam quality improves while being amplified in edge emitting broad area semiconductor amplifiers with a periodic structuring of the electrical contacts, in both longitudinal and lateral directions. A spatio-temporal traveling wave model is used for simulations of the dynamics and nonlinear interactions of the optical fields, induced polarizations and carrier density. In the case of small beam amplification, the optical field can be expanded into few Bloch modes, so that the system is described by a set of ODEs for the evolution of the mode amplitudes. The analysis of such model provides a deep understanding of the impact of the different parameters on amplification and on spatial (angular) filtering of the beam. It is shown that under realistic parameters the twodimensional modulation of the current can lead not only to a significant reduction of the emission divergence, but also to an additional amplification of the emitted field.