Scheibenzuber, W.W.ScheibenzuberSchwarz, U.T.U.T.SchwarzSulmoni, L.L.SulmoniCarlin, J.F.J.F.CarlinCastiglia, A.A.CastigliaGrandjean, N.N.Grandjean2022-03-042022-03-042011https://publica.fraunhofer.de/handle/publica/22562510.1002/pssc.201000920We present an experimental technique to measure the absorption spectra of the absorber section of GaN-based multi-section laser diodes using optical gain spectroscopy. We find that the absorption of the examined laser diodes decreases with increasing negative bias, which results from a reduction of the internal field in the quantum wells by the external voltage. A maximum modal absorption as high as 250 cm(-1) at the laser wavelength of 413nm is measured at 1V absorber voltage.enlaser diodegroup III-nitridesabsorption667journal article