A cylindrical two-dimensional diode-laser assembly includes fractionally-cylindrical dielectric segments bonded in a circular aperture in a metal heat-sink. Diode laser bars are located in gaps between the segments with light from the diode-lasers directed inwardly. The segments are made by cutting slots in one end of a tube of the dielectric material with the width of the slots corresponding to the width of the gaps and the part of the tube between slots providing the segments. The slotted tube is metallized and the slotted end of the tube is inserted into the heat-sink aperture with an unslotted part of the tube outside the aperture. The slotted part of the tube is bonded in the aperture and the unslotted part of the tube separated from the slotted part leaving the segments bonded in the aperture.