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Conventional diode lasers suffer from electron-hole recombination outside of their active region [primarily in the optical confinement layer (OCL) but also in the wetting layer in the case of quantum dot (QD) lasers]. This parasitic recombination negatively impacts the laser’s operating characteristics by raising the threshold current, making it more temperaturesensitive (decreasing the characteristic temperature), and leading to sublinear light-current characteristics. One proposed solution to this problem is the addition of asymmetric barrier layers (ABLs) in the OCL – one on each side of the active region. Ideally, if the ABLs are properly tuned, parasitic recombination outside of the active region (i.e., in the entire OCL) should be entirely suppressed. However, due to material constraints, it may be desirable to first manufacture a laser with only a single ABL suppressing parasitic recombination only on one side of the OCL. Here we study the effect of a single ABL on the steady-state operation of QD lasers. Our theoretical model is based on the set of rate equations for charge carriers in the multilayer structure and photons. We show that, despite the limited improvement to output optical power, the addition of a single ABL significantly improves the temperature stability of the laser – its characteristic temperature is much higher than that of the conventional QD laser. Our study thus justifies the concept of using even a single ABL in injections lasers for improving their operating characteristics.
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