Comparison of gain measurement techniques for 1.3μm quantum dot lasers

This paper reports on the direct comparison of Hakki-Paoli and segmented contact method gain spectra measurement techniques for InAs/GaAs 1.3μm quantum dot laser material. This was made possible by realizing a single-mode segmented contact device structure. The differences in required apparatus, ease of measurements, signal to noise ratio, and relative advantages and disadvantages of these two complementary techniques are discussed under continuous wave operation. As expected, at current densities (prior to possible self heating effects) the techniques are shown to give essentially identical results. However, the segmented contact method is demonstrated to be more accurate for internal loss measurements. A method to remove self heating effects in the Hakki-Paoli measurements is described and allows the gain and spontaneous emission measurements to be performed at carrier densities as high as 5.5kA/cm 2 with a constant cavity temperature.