An optical device may include a substrate including a conductive core, a first layer stack on a first surface of the conductive core, a conductor-filled trench extending through the first layer stack to the conductive core such that the conductor-filled trench is on the first surface of the conductive core, and a second layer stack on a second surface of the conductive core. The optical device may include a vertical-cavity surface-emitting laser (VCSEL) chip above the conductor-filled trench. The VCSEL chip may include an array of VCSELs. A size of the conductor-filled trench may match a size of the VCSEL chip, match a size of an emission region of the array of VCSELs, or be greater than the size of the emission region of the array of VCSELs and less than the size of the VCSEL chip.