Analysis of the gain distribution across the active region of InGaAs-InAlGaAs multiple quantum well lasers

Spectral gain measurements for two InGaAs-InAlGaAs multiple width quantum well structures, with inverse-configured active regions, have been presented. One structure consisted of wide quantum wells near the p-side and narrow quantum wells near the n-side of the active region. The other structure consisted of narrow quantum wells near the p-side of the active region with wider quantum wells near the n-side. It is shown that, for the same operating conditions, the structure with wide quantum wells on the p-side of the active region provided a 15% broader gain spectrum in comparison to the structure with narrow quantum wells on the p-side of the active region. The analysis of the results shows non-uniform carrier distribution across the active region of the structures, where the structure with wide quantum wells near the p-side of the active region provided 65% more gain in comparison to the structure with narrow quantum wells near the p-side of the active region. The gain distribution results have been compared with that obtained for the phosphorous quaternary structures in other literature and have shown there is some evidence to suggest that the gain distribution is more uniform in aluminium quaternary than phosphorous quaternary material.