A Temperature-Insensitive Semiconductor Laser

摘要

Highly temperature-stable operation is an essential feature required of long-wavelength semiconductor heterostructure lasers for telecommunications.Commercial lasers with either bulk or quantum-well (QW) active regions sufferfrom rather poor temperature stability. The all-important parameter To, whichdescribes empirically the temperature dependence of the threshold current densityjth and is defined as To = (a ln( jth)/a7)-1, does not exceed 100 K in the bestcommercial lasers. Quantum-dot (QD) lasers, exploiting a zero-dimensional (OD)active medium were proposed years ago" and one of their main predictedadvantages was high temperature stability. Nevertheless, despite significant recentprogress in the fabrication of QD lasers,3-12 their temperature stability has fallenfar short of expectations. Although the best results for To in QD lasers are quiterespectable, matching and even exceeding the best QW results at roomtemperature, so far they have been nowhere near the predicted "infinite" valuesthat would justify regarding the laser as temperature insensitive.