Optimal output mirror reflection coefficient for powerful InGaAs/AlGaAs laser diode arrays

The optimal value of the output mirror reflection coefficient providing the maximum output power under a constant level of electrical power consumption and the maximum external (slope) lasing efficiency for powerful InGaAs/AlGaAs laser diode arrays (LDA) has been estimated experimentally and theoretically. The LDA active layer overheating and amplified spontaneous emission have been taken into account. For advanced LDAs with the thermal resistance of 0.2 K/W and the internal optical loss of 0.5 cm−1 the optimal output mirror reflection coefficient is equal to 20%. This value is shifted to the high output mirror reflection coefficient side with a decrease of the LDA excitation level, the LDA thermal resistivity and the internal optical loss. It has been shown that the right selection of the output mirror reflection coefficient optimal value provides the LDA operation with 20% excess of the lasing output power and 10% excess of the external lasing efficiency.

► The optimal value of the output mirror reflection coefficient for powerful LDAs has been estimated.
► For advanced LDAs the optimal output mirror reflection coefficient is equal to 20%.
► It is shifted to the high values side with a decrease of the LDA thermal resistivity and optical loss.
► The right selection of LDA reflection coefficient provides operation with 20% output power excess.