High Single Fundamental-Mode Output Power From 795 nm VCSELs With a Long Monolithic Cavity

A high fundamental-mode output power was achieved from a 795-nm vertical-cavity surface-emitting laser (VCSEL) with a long monolithic cavity. The epitaxial cavity spacer between active region and N-DBRs yields high diffraction losses for higher order transverse modes. The single mode optical power of 5.6mW under continuous wave was demonstrated in the long-cavity VCSELs with $4.5~\mu \text{m}$ oxide aperture. Above 10° reduction in divergence was found for long-cavity VCSELs. Decreased thermal resistance was also demonstrated in long cavity VCSELs due to additional homo-structure which can be as heat spreading layer. The change of VCSEL structure is only in epitaxy layer. So the fabrication process is completely same with the conventional fabrication, therefore, improves reproducibility and yield.