Laser patterned desorption (LPD) is a versatile new in situ etching technique developed for optoelectronic device fabrication. With this technique, laser heating is used to locally desorb GaAs or AlGaAs quantum well (QW) layers during a pause in the crystal growth. After the LPD step, crystal growth is resumed, burying the patterned quantum layer within the crystal. By applying LPD to QW active layers, multiple wavelength diode lasers have been produced. Transmission electron microscopy (TEM) and photoluminescence are used to quantify the lateral profile of the QW thickness. The high resolution TEM shows the presence of nm-scale inclusions near the region where desorption took place. The inclusions are tentatively identified as Al remaining from the desorption of AlGaAs. © 1989.