Channeled substrate buried (CSB) heterostructure laser diodes have been developed successfully. To fabricate CSB lasers a two‐step liquid‐phase epitaxial (LPE) growth in conjunction with the standard etching techniques was required. The first step of the LPE process was to grow ap‐type GaAs internal current confining layer on then‐GaAs substrate, followed by the etching of parallel V‐grooves along the [011] direction. The second LPE process was to grow a four‐layer laser structure over the V‐grooves. Due to the smoothing effect, an active layer with a crescent‐shaped cross section was formed. Because of the undercutting effect during the etching process, the active layer became very wide, i. e.,∼25μm. This resulted in a far‐field pattern along the junction plane with multifilaments. Each filament had a full angle at half maximun of 8∼10°. The smallest threshold current was found to be 0.88 A, which corresponds to a threshold current density of 8 KA/cm2. Its mode profile was in the range of 8,360 Å to 8,400 Å.