In electronics, analog signal processing/computation suffers from parasitic capacitance which leads to slew rate—which is the maximum rate of voltage change allowed, so handling super-high frequency becomes impossible.
Is this still true for optical signal processing/computation, such as optical (frequency) mixer or optical frequency multiplier? If so, what would be the physics behind?
Best Answer
Your question includes both the conversion (since you speak of processing) and light propagation. Conversion involves electronics, as @Nasha mentions, and thus is directly impacted by the slew rate.
Light propagation speed is reduced (with respect to that in vacuum) by the refractive index of the material. The physics causing the finite slew rate is also also causing the fact that the refractive index of the material is always greater than 1.