Low current, high power laser diode bar

A method of fabricating a laser diode bar, the method comprising:

• providing a semiconductor substrate;
• forming a first semiconductor layer of a first conductivity type on a front side of the semiconductor substrate;
• forming a semiconductor stack on a front side of the first semiconductor layer,
• wherein the semiconductor stack comprises at least one first semiconductor cladding layer of the first conductivity type on the first semiconductor layer, and
• wherein an electrical conductivity of the first semiconductor layer is greater than an electrical conductivity of each first semiconductor cladding layer;
• forming a trench in the semiconductor stack down to the first semiconductor layer to divide the semiconductor stack into a first laser diode stack and a second laser diode stack;
• forming a first electrode layer on the first laser diode stack and on the first semiconductor layer in the trench to establish a series connection between the first laser diode stack and the second laser diode stack;
• and
• forming a recess on a back side of the semiconductor substrate and directly beneath the first laser diode stack, wherein the recess extends from the back side of the semiconductor substrate to a back side of the first semiconductor layer.

A laser diode bar comprising:

• a semiconductor substrate comprising a first semiconductor layer of a first conductivity type;
• a plurality of additional semiconductor layers on an upper surface of the first semiconductor layer, the plurality of additional semiconductor layers comprising a first cladding layer of the first conductivity type, an active region for generating photons, and a second cladding layer of a second conductivity type;
• a plurality of trenches in the plurality of additional semiconductor layers and separating the plurality of additional semiconductor layers into a plurality of laser diode stacks, wherein the first semiconductor layer is a common cathode contact for each laser diode stack;
• a plurality of electrically insulating barriers, wherein each electrically insulating barrier is positioned in the first semiconductor layer between a different pair of laser diode stacks, wherein the plurality of laser diode stacks are serially electrically connected;
• and
• a plurality of shunt electrode layers on a back side of the semiconductor substrate, wherein each shunt electrode layer of the plurality of shunt electrode layers is positioned underneath a corresponding laser diode stack of the plurality of laser diode stacks.