High-performance wafer-bonded bottom-emitting 850-nm VCSEL's onundoped GaP and sapphire substrates |
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Authors: | Chao-Kun Lin Sang-Wan Ryu Dapkus P.D. |
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Affiliation: | Center for Photonic Technol., Univ. of Southern California, Los Angeles, CA; |
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Abstract: | We have demonstrated high performance wafer-bonded bottom-emitting 850-nm vertical-cavity surface-emitting lasers (VCSEL's) on transparent substrates. The free-carrier absorption of the substrate was avoided by using undoped GaP or sapphire substrates. The maximum external quantum efficiency approaches 48% while the threshold current remains as low as 550 μA for the 6×6 μm2 VCSEL's bonded on GaP substrates. VCSEL's with 8.6×8.6 μm2 aperture bonded on sapphire substrates also exhibit threshold currents of 800 μA and external quantum efficiencies of 33.2%. The difference in efficiency between these two devices results from the change of the refractive index of the exit medium |
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