In this study, we employed bulk (0001) AlN substrates for the metalorganic chemical vapor deposition growth of AlGaN multi-quantum-well heterostructures in an Aixtron 6 × 2″ close-coupled showerhead reactor. The wafers were fabricated into cleaved bars with a cavity length of ∼1 mm. Two different layer structure designs are presented in this work. Both laser bars were optically pumped by a pulsed 193 nm ArF excimer laser at room temperature. The lasing wavelengths are 243.5 nm and 245.3 nm with threshold power density 427 kW/cm2 and 297 kW/cm2, respectively. Both laser bars showed transverse electric-polarization-dominated optical emission when operating above threshold. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.