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Recommendations for the 6 W laser diode NUBM44

Although the laser is relatively impervious to case operating temperature, we do recommend that suitable heat sinking is used with NUBM44 and other high-power laser diodes. Specifically, a low-thermal resistance (ideally less than 1.5 C/W) mount should be used due to a large amount of heat generated (approximately 12 W) when this laser is operated at full power. A laser diode mount with low thermal resistance will reduce the amount of localized heating produced by the laser element and minimize the path to thermal ground. Such a TO package mount will also reduce the amount of thermal drift, which affects both the power and wavelength. Thermal resistance can be minimized by pressing the TO header against a flat heat spreader surface machined from materials such as Aluminum, Copper or Brass; as well as by soldering it; applying a thin layer of thermal paste can also be helpful.

In order to collimate this laser diode well and collect as much light as possible, we recommend using a collimation lens with a high numerical aperture (e.g., NA greater than 0.50). This is because the far-field divergence on the fast axis is typically 44 degrees. Without a fast (high-NA) lens, some of the power will be lost. Using a longer focal length lens will improve the blue laser diode’s ability to be collimated. To further reduce the slow axis divergence, it is possible to expand the beam on the slow axis using two cylindrical lenses, which Opt Lasers also provides on its webstore. However, in certain applications having a short working distance, it is sufficient to use only a single collimation lens.