Operations in a new high-power laser called the twin-ridge substrate (TRS) laser, which has been previously proposed by the present authors, are discussed in full detail on a theoretical and experimental basis. From the viewpoint of practical applications, the following considerations are discussed: device design, device fabrication, the catastrophic failure limit, degradation, life and the oscillation mode. A stable fundamental transverse-mode operation has been obtained up to a maximum power of 40 mW. The typical threshold currents and differential quantum efficiencies are 50–60 mA and 40–50% (both facets), respectively. The typical beam divergences in the far-field pattern are 8° and 23° in the directions parallel and perpendicular to the junction plane, respectively. The room temperature lifetime is expected to exceed 66000 hours at 20 mW.