Detecting localized heating within a high-power bar-based laser diode stack can help in screening devices for longevity. Localized heating is generally a signature of early power degradation or catastrophic failure of a bond joint, such as solder imperfections. Resolution of emitter level spectral measurements can be used to generate a thermally mapped near field image of a free space multi-emitter laser diode bar or stack. Approaches using this technique to obtain the right accuracy, calibration and adjustment to different device properties are discussed.
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