Multi quantum well electroabsorption-modulated laser characterised by hard X-ray microprobe

A multi quantum well electroabsorption-modulated laser is a semiconductor device employed in long-distance, high-frequency optical-fibre communication. The most advanced devices involve monolithic integration of two functions, electroabsorption modulator and distributed feedback laser, at the chip level. Devices are manufactured by state-of-the-art methods of substrate masking and vapour deposition, but the results of this process are judged empirically. Here scientists have used an ESRF hard X-ray microprobe to characterise the semiconductor material constituents of such a device with unprecedented detail.