Wavelength conversion using a [111]A MQW-SOA with escape time reduced by compressive strain-induced piezoelectric...

Here, a technique for implementing an all-optical wavelength converter based on the quantum-confined Stark effect (QCSE) influenced by piezoelectric fields in a semiconductor optical amplifier with compressively strained zinc-blende multi-quantum well grown along the [111]A direction and embedded in the intrinsic layer of a p-i-n diode is presented. The originality and crucial aspect of the technique used is that the piezoelectric fields, induced by the compressive strain within the quantum wells (QWs) of the amplifier with an orientation parallel to that of the built-in field of the structure, make it possible to accelerate the absorption recovery and to perform a fast wavelength conversion over a wide range of the continuum. Specifically, the built-in p-i-n electric field and the piezoelectric fields induce a QCSE and unevenly tilt the potential energy profile of the QWs. This dramatically reduces the energy between the effective height of barriers and the quantized energy of carriers, remarkably due to the piezoelectric fields, thereby decreasing the escape time of carriers from wells and accelerating absorption recovery. Consequently, a strong negative chirp is induced into the converted signal pulses, allowing their compression after passing through a blue-shifted optical filter. Up- and down-conversions at 150 and 1300 Gb/s, respectively, were theoretically predicted in an ideal case, and experimentally, both were error-free demonstrated at 40 Gb/s in a total range of 29 nm, employing a straightforward scheme, with the possibility of operating at 100 Gb/s.