A new quantum structure ‘multiple quantum barrier and multiple quantum well in active region’ design for laser diode applications

A new quantum structure of AlGaAs laser for high temperature operation has been demonstrated. The new laser has a multiple-quantum barrier (MQB) structure located in the middle of the active region. This location of the MQB improves the efficiency of the hole injection into the active region compared to conventional MQB structure. It also maintains the suppressible effect of the electron overflow from the active region to the cladding layer. Moreover, multiple-quantum wells (MQWs) are integrated at each side of MQB to minimize the possible overflow of electrons by improving the recombination efficiency. The continuous-wave laser threshold current (Ith) and the differential quantum efficiency (ηd) have been improved about 50% by integration of MQW to the MQB in active laser. The Ith as low as 31.1 mA (ηd: 0.44 mW/mA) was obtained on a ridge waveguide MQB + MQW in active laser of 4 μm wide and 300 μm long having as-cleaved uncoated facets.