Effect of transport on high-speed dynamic performance of quantum-well semiconductor optical amplifiers

The advances in semiconductor device integration have generated interest in the integration of semiconductor amplifiers with laser sources for communication applications. For example, the enhanced output power of optical laser modulator sources integrated with amplifiers can have appreciable benefit. In such structures however, care must be taken to ensure that power levels within the amplifier do not become sufficiently large for patterning in the amplifier to cause either significant system amplitude distortion or chirp. For Multiple Quantum Well (MQW) devices, carrier transport effects must be considered in detail as the carrier population in the barrier level, changing in a different manner from that in the quantum wells, contributes both indirectly to the overall amplitude distortion imposed by the amplifier and directly to the chirp. This paper therefore reports a detailed study of the role of carrier transport in optical amplifiers operating at high power, at modulation rates in excess of 10 Gb/s. It is shown that transport effects can substantially alter the chirp of the device.