Tunable GaAs-based high power tapered amplifiers in an external cavity setup

In this paper, we report on tapered amplifiers based on the GaInAs/AlGaAs-on-GaAs material system, where the active region consists of a 7 nm thick compressively strained InGaAs single quantum well with an indium content of 31%. The devices comprise an index-guided ridge waveguide section acting as a master oscillator which feeds a gain-guided tapered section. A novel split contact design enables us to separately adjust the currents in the ridge- and the taper section. Therefore, a modulation of the output power can be realized by varying the comparatively small ridge current only.