Experimental investigation of loss and gain characteristics of an abnormal InxGa1-xAs/GaAs quantum well structure

Abstract

In this Letter, the loss and gain characteristics of an unconventional In x Ga 1−x As∕GaAs asymmetrical step well structure consisting of variable indium contents of In x Ga 1−x As materials are measured and analyzed for the first time, to the best of our knowledge. This special well structure is formed based on the indium-rich effect from the material growth process. The loss and gain are obtained by optical pumping and photoluminescence (PL) spectrum measurement at dual facets of an edge-emitting device. Unlike conventional quasi-rectangle wells, the asymmetrical step well may lead to a hybrid strain configuration containing both compressive and tensile strains and, thus, special loss and gain characteristics. The results will be very helpful in the development of multiple wavelength InGaAs-based semiconductor lasers.

Absorption loss properties and Stokes shifts of InGaAs-based self-assembled well-wire-hybrid quantum structures

“…In order to validate the effectiveness of the proposed method for measuring the absorption loss spectrum, we compare the measured absorption spectra with that in [30]. The latter is the latest reported method for the absorption loss measurement.…”

“…The result is shown in figure 6, where the sample used for this purpose has the completely identical material composition and quantum structure with the device used in [30], as they are derived from the same one wafer, and all the measurement conditions are set the same as well. In figure 6, the blue curve represents the absorption spectrum measured with the proposed method in this paper and the green one is a duplicate of the absorption spectrum presented in [30]. The result shows that the absorption peaks in the two curves coincide well with each other in the energy.…”

“…The result shows that the absorption peaks in the two curves coincide well with each other in the energy. The slight difference between the two absorption spectra in the lower energy range should be from the sample processing-induced error in the previous method [30], because it is actually difficult to realize 100% transparency for the device by coating at each end of the sample. This would lead to a certain measurement error introduced into the absorption coefficient calculation with the corresponding theoretical model.…”

“…Currently, the mainstream methods for the absorption loss measurement of semiconductor light-emitting devices involve the Hakki-Paoli method [20,21], the external differential efficiency method [22], the single-pass measurement method [23][24][25][26][27][28][29], and the double-pass method [30]. In the Hakki-Paoli method, the absorption loss of a device is obtained by measuring the gain spectrum of the active material in a Fabry-Perot resonator.…”

“…In addition, the absorption spectrum cannot be obtained with this approach, too. With single-pass and doublepass methods, although the overall absorption spectrum of the material can be obtained, the sample requires a special treatment, including anti-reflection coatings, or inclined surfaces at one or both ends of the sample to prevent light from roundtrips within the chip [23][24][25][26]30]. Others require grinding samples into specific shapes, like multipass sample geometry, to separately obtain the s-polarized and p-polarized light of the material [27,28].…”