Reflectance modulation thermography has been used to determine facet temperatures of InGaAs/GaAs double quantum well (QW) GRINSCH ridge-waveguide lasers possessing band gap shifted extended cavities (BSECs). The incorporation of BSECs produced by mega-electron-volt ion-implantation enhanced QW intermixing, significantly decreased the laser facet temperatures and should result in increased device longevity prior to the onset of catastrophic mirror failure. Low energy implants in Al-free InGaAs/InGaAsP/InGaP laser structures exhibited large effective diffusivities of intermixing enhancing defects from the implant damage regions. This latter material system is particularly well suited for the implementation of BSECs as end of range damage from the implant can be kept spatially isolated from the optical mode regions.