An InGaAs based distributed Bragg reflector (DBR) laser operating at 2 μm was fabricated and evaluated as a light source for real-time gas sensing for which mode-hop free operation throughout its lifetime is essential. We therefore performed an aging test to confirm mode-hop free operation. Current was injected into the active/SOA region and/or the DBR/phase control (PC) region at 85 °C. The changes in threshold current and wavelength were not significant after 5000 h of aging. As the wavelength shifts for DBR and PC current after aging are comparable, we confirmed mode-hop free operation of the laser throughout its lifetime as a gas-sensing light source.