For the ridge waveguide (high index contrast waveguide) MQWs laser that I recently fabricated, the threshold is low at less than 20 mA, but the output power is also low at just a few uW. This seems contradictory (or maybe not?).
Few microWatts, but at what current? It is worthy to compare output power of two lasers at the same current, and probably laser with lower threshold will give larger output at the same current (not obligatory but probably). Alternative explanation - at 20 mA you obtained amplified spontaneous emission, but not laser generation, and lasing will onset at higher current. Few microWatts can be expected from ASE, but you may also measure spectrum. Lasing has commonly narrower spectrum than ASE. I am not an expert in laser diodes and write the answer from general considerations.
Sample surface is cleaved either after or before the front DBR. In the first configuration, the reflectivity of the front DBR was relatively high (~50%) which causes lower threshold current but also lower output power. The temperature play also a role in determining the output power for example : in integrated III-V semiconductor,the maximum output power is around 4 mW at 20°C, and the output power is higher than 0.8 mW at 60°C.
I advise you to read the following paper:
Ultra low threshold, electrically pumped quantum dot photonic crystal nanocavity laser
Bryan Ellis, Marie A.Mayer, Gary Shambat, Tomas Sarmient, James Harris , Eugene
E.Haller , and Jelena Vuckovic
mail: [email protected]
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