As shown in Figure 1, there are fundamental differences between electrical and optical signals. Electrical signals describe current and voltage in the RF domain and are real-valued, baseband signals. A baseband signal has non-zero spectral contents near DC and is lowpass.
Optical signals, on the other hand, are analytic, narrowband signals with a complex-valued envelope; i.e., a complex number with real and imaginary parts describing amplitude and phase modulation of the optical carrier. Representing all the attributes of a photonic signal in an electrical signal requires resorting to unnatural, inefficient, and potentially inaccurate models.