High power vertical cavity surface emitting lasers(VCSEKLs) with large aperture have been fabricated through improving passivation, lateral oxidation and heat dissipation techniques. Different from conventional three quantum well structures, a periodic gain active region with nine quantum wells was incorporated into the VCSEL structure, with which high efficiency and high power operation were expected. The nine quantum wells were divided into three groups with each of them located at the antinodes of the cavity to enhance the coupling between the optical field and the gain region. Large aperture and bottom-emitting configuration were used to improve the beam quality and the heat dissipation. A maximum output power of 1.4 W was demonstrated at CW operation for a 400 μm-diameter device. The lasing wavelength shifted to 995.5 nm with a FWHM of 2 nm at a current of 4.8 A due to the internal heating and the absence of active water cooling. A ring-shape far field pattern was induced by the non-homogeneous lateral current distribution in large diameter device. The light intensity at the center of the ring increased with increasing current. A symmetric round light spot at the center and single transverse mode operation with a divergence angle of 16° were observed with current beyond 4.8 A.
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