One Connection at One Terabit per Second
Another reason for trying to use optics is for its speed. Optical nonlinearities have been measured down to the femtosecond (10-15 s), whereas electronics, because of the mobility of electrons in a semiconductor, has a built-in limit at around 10 picoseconds (10-12 s). The large bandwidths also allow us to go ultrafast. It frees us from the inductive and capacitive limitations of electronics. We have recently demonstrated an all-optical fiber logic AND gate, a NOT gate, a XOR gate, a 1.6-terahertz
Figure 5.
A miniaturized version of one of the modules of the simple optical processor.
Figure 6.
An example of three-dimensional planar optics.
Figure 7.
An ultrafast all-optical fiber logic gate.
optical clock, a 2.5-gigabits-per-second multiplexer (Whitaker et al. 1991), and a 254-bit optical dynamic RAM (Figure 7). This is the beginning of a new digital technology that has the potential of working in the terahertz regime.