Full Text: FreePDF(1.2MB) Summary: We have developed InGaAs-based VCSELs operating around 1.1 µm for high-speed optical interconnections. By applying GaAsP barrier layers, temperature characteristics were considerably improved compared to GaAs barrier layers. As a result, 25 Gbps 100 error-free operation was achieved. These devices also exhibited high reliability. No degradation was observed over 3,000 hours under operation temperature of 150 and current density of 19 kA/cm2. We also developed VCSELs with tunnel junctions for higher speed operation. High modulation bandwidth of 24 GHz and a relaxation oscillation frequency of 27 GHz were achieved. 40 Gbps error-free operation was also demonstrated.