Contents 1. Introduction
The ultra-high speed (> 20 Gbit/s) operations of vertical-cavity surface-emitting lasers (VCSELs) have been demonstrated for their potential implementation in optical interconnections and next-generation data communications [1], [2]. The lasing wavelengths of most of them are in the range between and . By extending the lasing wavelength to , which is the minimum fiber dispersion wavelength, the link distance can be expanded to beyond 1 km. However, it is still a challenge for VCSELs to operate at the ultra-high speeds in elevated temperatures because of the power saturation due to their small active volume [3]. We have thus tried to integrate a 45° mirror and an aspheric lens onto an InGaAlAs multiple-quantum well (MQW) distributed feedback (DFB) laser, namely a lens-integrated surface-emitting laser (LISEL) for conducting surface emissions, and a 10 Gbit/s laser operation of the laser has been demonstrated [4].
