Nonlinear Dynamics in Semiconductor Lasers - Abstract

Wenzel, Hans

Modal behaviour of broad area lasers at high output power

Broad area diode lasers are the workhorses for modern laser systems. A large lateral emission aperture of typically 100 μm is needed in order to ensure reliable operation at 10 W and over which means that these device operate in multiple lateral modes, limiting how effectively they can be laterally collimated. The lateral modes are induced and influenced by several physical effects, specifically: (a) built-in refractive index profiles from structures such as etched trenches or impurity induced disordering, (b) gain, loss and associated anti-index profiles arising from the injected carrier density, (c) self-heating (thermal lensing) induced by the current flowing through the device and absorption, (d) self-focusing via the dependence of the injected carrier density profile on the optical intensity profile. In all cases, higher currents lead to more lateral modes and wider far fields, degrading the beam quality. In this talk we will present results of a combination of numerical studies and diagnostic measurements to determine physical factors limiting the lateral far field angle in state of the art broad-area lasers emitting at a wavelength of 975 nm.