Influence of local heating on current-optical output power characteristics in Ga1−xAlxAs lasers

Abstract

Available optical output powers from the Ga1−xAlxAs lasers are limited by the catastrophic optical damage or output power saturation due to local heating on the facet. Especially, the saturation of current-optical output power characteristically occurs during the operations at relatively low output power. This report describes the degradation process in an active region for lasers with the striped window as an electrode with respect to current-optical output power characteristics, electroluminescence image observation, and measurement of temperature rise at the facet and the cavity inside using laser Raman spectroscopy. The nonluminescing dark region observed in rapidly degraded lasers develops from the facet to the cavity inside. The dark region is so nonradiative that electron-hole recombination in that region produces heat rather than light. The measured local temperature on the facet drastically rises and the area influenced by local heating extends into the cavity inside. Although the threshold current increases by only 16%, the optical output power is saturated and finally the initial optical output power (20 mW/facet) is hardly maintained. It is found that the change in current-output power characteristics almost corresponds to the calculated results which incorporated temperture dependence of local absorption loss in the dark region.

Self-consistent calculation of facet heating in asymmetrically coated edge emitting diode lasers

“…Here, the temperature drastically drops to the bulk value. The shape and the extension of the heated region at the facet agrees with an experimental observation of the temperature profile at the mirrors of a Ga 1−x Al x As laser by means of Raman spectroscopy [30], and with data describing the axial temperature decay at the facets of quantumwell lasers which are found from spatially resolved electroluminescence spectra [17,31]. As an example, in [31], the temperature decay was found to be exponential with a characteristic length of about 6 µm (1/e-point).…”

“…When reabsorption sets in at the facets, the facet temperature increases non-linearly with the pumping current [33][34][35]. In particular, a marked increase of the mirror-heating rate is observed at the threshold of lasers with high surface recombination [30,32,34]. Such observations confirm the idea of a power-dependent facet heating caused by reabsorption.…”

Photon Recycling in Semiconductor Thin Films and Devices

“…In the past, this characteristic has been studied theoretically and experimentally in the broad field of laser diodes to determine the threshold for lasing. [113][114][115] In addition, it also plays an important role in showing properties of laser diodes with and without PR effects. In 1990, Gigase et al reported that the threshold pump power of an AlGaAs-GaAs ridge quantum well laser diode can decrease by PR.…”

Direct measurement of facet temperature up to melting point and cod in high-power 980-nm semiconductor diode lasers

“…While it is reasonably straightforward to estimate the junction temperature as a function of current/power (e.g., from the thermally induced shifts in the laser emission wavelength) it is a considerably more difficult task to determine the local facet temperature. Strategies for measuring the facet temperature include the following: Raman microprobe microscopy [22] which relies upon measuring the Stokes/anti-Stokes phonon line intensity ratio. A drawback of this technique is it tends to be very slow and is typically limited to an accuracy of 20 K. Also, the relatively high excitation laser power may itself cause heating of the facet, thereby obscuring the actual facet temperature.…”