Analysis of mechanical strain and temperature profiling in high-brightness, parabolic bow-tie laser arrays

With the widespread use of laser diodes in modem industry there has been an increasing demand for high optical output power devices with good beam quality and, ideally, low production and packaging costs. Reliability and long lifetime are essential requirements since they determine the extent to which such sources will be utilised. The devices of interest here are arrays of parabolic bow-tie lasers which have been specially designed to achieve high power with high brightness without the need for re-growth or sophisticated device fabrication. This paper presents a comparative study on laser diode arrays to investigate the effects of scaling and device geometry on device operation, including degradation and ageing. Temperature profiles at the array facets have been obtained using a thermal imaging system. The HgCdTe-based detector operates in the 1-5.5 mu m wavelength range. The results obtained indicate a smaller increase in temperature (2-5 degrees C) in uncoupled arrays with respect to phase-coherent arrays and a considerable increase in temperature with increasing number of elements in the array. Such considerations are essential to properly manage thermal dissipation and improve the operational characteristics of such devices.