A diode laser includes a p-contact layer, a n-contact layer, and a wafer body disposed between the p-contact layer and the n-contact layer, the wafer body having a front end and a back end. The diode laser further includes a first grating comprising a plurality of grooves defined in the wafer body and extending between the front end and the back end at a first tilt angle, and a second grating comprising a plurality of grooves defined in the wafer body and extending between the front end and the back end at a second tilt angle, the second tilt angle opposite to the first tilt angle. A coupling region is defined in the wafer body by interleaving portions of the first grating and the second grating. The interleaving portions provide coherent coupling of laser beams flowing through the first grating and the second grating.