Local mirror temperatures of red‐emitting (Al)GaInP quantum‐well laser diodes by Raman scattering and reflectance modulation measurements

Temperature rises were measured on cleaved, uncoated mirror facets of junction‐side‐up mounted (Al)GaInP laser diodes as a function of the injection current by Raman spectroscopy via the Stokes/anti‐Stokes phonon line intensity ratio and the phonon line shift as well as by reflectance modulation as a novel application for laser mirror characterization. Below the threshold current the temperature rise is due to Joule heating of the drive current across the ohmic resistor and is ΔT≂35 K at threshold. Above threshold a significant power‐dependent heating caused by absorption of laser radiation is superimposed. In this regime the temperature increase is considerably high, i.e., ΔT≥100 K at 4 mW for 5‐μm‐wide ridge lasers. The different measurement techniques have produced consistent data.