Thermal characteristics of high-power, long pulse width, quasi-CW laser diode arrays

2-micron solid-state lasers operating at moderate to high pulse energies require high power quasi-CW laser diode arrays (LDAs) operating at a nominal wavelength of 792 nm with pulse durations of at least one millisecond. This long pulse duration is one of the main causes of limited lifetimes for these arrays. Such relatively long pulse durations cause the laser diode active region to experience high peak temperatures and drastic thermal cycling. This extreme localized heating and thermal cycling of the active regions are considered the primary contributing factors for both gradual and catastrophic degradation of LDAs. This paper describes the thermal characteristics of various LDA packages, providing valuable insight for improving their heat dissipation and increasing their lifetime. The experiment includes both direct measurement of thermal radiation of the LDA facet using a high resolution IR camera and indirect measurement of LDA active region temperature by monitoring the wavelength shift of the near-IR light. The result of thermal measurements on different quasi-CW LDA packages and architectures is reported.