Highly reliable and stable-lateral-mode operation of high-power 0.98-μm InGaAs-InGaAsP lasers with an exponential-shaped flared stripe

A 0.98-μm InGaAs-InGaAsP-GaAs strained quantum-well (QW) laser with an exponential-shaped flared stripe is proposed for high-power, highly reliable operation. The stripe width is wider at the front facet to reduce the optical density by widening the spot size. The stripe width is narrower at the rear facet for stable lateral-mode operation. The stripe width in the transient region is varied exponentially along the cavity for smooth mode transformation. We showed that this structure expands the spot size effectively without any deterioration in stable lateral-mode operation. The kink-occurrence output power is determined only by the stripe width at the rear facet, and the spot size at the front facet is a function only of the stripe width at the front facet. The maximum output power is 40-60% higher than that of ordinary straight-stripe lasers for the same kink-occurrence output power. Testing at 150 mW showed stable operation with an estimated lifetime of more than 200000 h at 25°C