In electrical interconnects, nonlinear signals (e.g. digital signals) are transmitted by copper wires conventionally, and these electrical wires all have resistance and capacitance which severely limits the rise time of signals when the dimension of the wires are scaled down.
Optical solution are used to transmit signals through long distances to substitute interconnection between dies within the integrated circuit (IC) package.
Conventional physical metal wires possess both resistance and capacitance, limiting the rise time of signals.
Bits of information will overlap with each other when the frequency of signal is increased to a certain level.
[1] Optical interconnections can provide benefits over conventional metal wires which include:[1] However, there are still many technical challenges in implementing dense optical interconnects to silicon CMOS chips.