A simple technique has been used to measure the two polarization-dependent absorption edges in a angle quantum well around 1.5 µm. The broadband spontaneous emission of an AR-coated semiconductor laser chip was used as the spatially coherent light source in conjunction with a grating spectrometer. Absorption edges for both TE and TM polarized light have been measured in single quantum well InGaAs/InGaAsP waveguides and modeled by the k-p method. By pumping the devices with a 1.3 µm semiconductor laser, absorption saturation was also studied. The resulting changes in the refractive index were calculated from a Kramers-Kronig transformation of the absorption changes. © 1996 American Institute of Physics.