Contents I. Introduction
On-chip optical interconnection is widely investigated for future interconnection of Si CMOS. The problems of electrical interconnection, such as Joule heating and signal delay, can be solved by introducing optical interconnection. Silicon photonics-based on-chip optical link using an external light source was demonstrated with 3 Gbit/s data transmission [1]. Since an optical link consisting of extremely low-threshold lasers capable of high-speed direct modulation is attractive for low-power consumption and easy assembling, integrated optical links using photonic crystal laser [2] and microdisk laser [3] were demonstrated. However, actual error rate measurements were not done yet. To obtain good data transmission, an efficient integrated structure with low threshold laser is needed. We demonstrated a sub-mA threshold operation of a membrane DFB laser as a light source for on-chip optical interconnection [4], [5]. A DFB laser has edge-emitting structure which is easy to integration with inplane output waveguide. By combining with semiconductor membrane structure, strong optical confinement to the active layers and large index-coupling coefficient of grating can be achieved. So we can expect highly efficient and low-power consumption optical link. In a previous experiment, monolithic integration of a membrane DFB laser, a passive waveguide and PIN-photodiode (PD) using butt-jointed built-in structure was demonstrated [6]. However, the results were limited to only static characteristics.
