Improvement Of Temperature Stability In Columnar Quantum Dots By Introducing Side Barriers With Larger Bandgap Energy For Semiconductor Optical Amplifiers

We have investigated the temperature dependence of InAs columnar quantum dots (CQDs) surrounded by InGaAsP barriers with different bandgap energies toward high-temperature performance for semiconductor optical amplifiers. It was found that larger bandgap energy in InGaAsP side barriers enabled to increase the quasi-Fermi level (F) separation between the conduction and valence bands from theory. We have fabricated two types of CQD-SOAs with different side barrier energies and compared temperature characteristics. Decrease in the material gains for CQD with a larger side barrier bandgap was suppressed by 20% with increasing temperature from 25 degrees C to 85 degrees C.