Abstract

Master Oscillator Power Amplifiers (MOPAs) are devices suitable for applications requiring high brightness light sources. In addition, MOPAs are promising candidates for high speed direct modulation, as required for applications such as LIDAR, free space optical communications and laser projection displays [1]. Monolithically integrated MOPAs usually comprise two sections: an index guided single lateral mode waveguide section acting as a Master Oscillator (MO) (in our case a Distributed Feedback laser (DFB)) and a gain-guided Power Amplifier (PA) section. Ideally, the single lateral and longitudinal mode generated by the MO is injected into the PA section where it undergoes free diffraction and amplification keeping its initial beam quality. However, MOPAs often exhibit instabilities that have been attributed to a combination of thermal effects and the residual reflectance at the amplifier front facet, which leads to the coupling of the MO modes and the modes of the full MOPA cavity [2].

© 2015 IEEE