Generation mechanics and reduction of "smile" of conduction cooled diode bars during the annealing process

During the process of annealing, the warpage of conduction cooled diode laser bars (CSs) packaged with indium solder is studied according to temperature difference along the direction of thickness of CSs. This investigation reveals that the smile of CSs is related to the annealing rate and the thickness of the packaging fixture. In theory, the smile can be eliminated by optimizing the annealing rate and the thickness of the packaging fixture when using two-sided isokinetic annealing method. Compared with the one side annealing, when the thickness of the fixture is more than 15 mm, the smile of CSs still can be well controlled by the two-sided isokinetic annealing. It provides theoretic evidences for eliminating smile during annealing and improving the performances of CSs.