It has been proposed that the temperature of the active layer in VCSELs could be inferred from the wavelength shift of the laser line. However, in VCSELs the laser emission wavelength is primarily selected by the cavity resonance, instead of the material gain peak. Hence the shift of the laser emission only provides an estimate of the temperature averaged over the whole cavity volume. We present a non-invasive microprobe technique for the temperature mapping of operating VCSELs, based on the analysis of the spontaneous electroluminescence emission transmitted through the DBR mirrors. While the sample is temperature stabilized and held onto a xy piezo stage, it is scanned across with an optical microscope (achieving similar to2 um spatial resolution). The signal is spectrally resolved and analysed by a CCD. By comparing the spectra taken under cw and pulsed current injection, the temperature contribution to the emission lineshape can be extracted straightforwardly. We demonstrate the capability of the proposed technique by mapping the temperature rise of a broad area proton implanted oxide VCSEL. Our results clearly demonstrate that the temperature rise is not uniform across the device cross-section, in contrast to the uniform temperature distribution measured by the laser wavelength shift method.
|Titolo:||Direct measurement of the local temperature distribution in oxide VCSELs|
|Data di pubblicazione:||2002|
|Nome del convegno:||Conference on Vertical-Cavity Surface-Emitting Lasers VI|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1117/12.469218|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|