FREE-SPACE OPTICAL INTERCONNECTION - A TECHNOLOGY COMPARISON OF VERTICAL-CAVITY SURFACE-EMITTING LASERS AND MULTIPLE-QUANTUM-WELL MODULATORS

We evaluate current vertical-cavity surface-emitting laser (VCSEL) and multiple-quantum-well (MQW) modulator technologies for low-fanout sys tem applications. Si-CMOS transimpedance receiver circuits are used in the comparison. The aggregate bandwidth per unit area is calculated f rom the bandwidth and the total on-chip power dissipation. The results indicate that the electrical power dissipation in the receiver circui ts dominates at low operating frequencies. At high operating frequenci es the receiver gain drops significantly, thus more electrical power i s dissipated in the transmitter to provide more optical power to the r eceiver to satisfy the voltage requirement at the receiver output. In VCSEL based systems, the optical power is generated entirely on-chip. Thus, only VCSELs with low threshold current and low series resistance would be able to provide the same aggregate bandwidth as the MQW modu lator based systems.