In a semiconductor lasers using quantum well gain medium, a quantum well
stack is mounted in an epi-down configuration. The epitaxial side of the
device may be directly bonded to an efficient heat transport system so
that heat may more easily leave the quantum well stack layers and be
disposed at a heatsink. Such a device runs cooler and exhibits reduced
loss mechanisms as represented by a laser system loss-line. External
cavity systems using this configuration may permit a high degree of
tunability, and these systems are particularly improved as the tuning
range is extended by lowered cavity losses.