Light strong field pulses

The subject of quantum optics is concerned with the quantum properties of the radiation field, i.e. the properties of photons. Since the word multiphoton has been used, it might seem that strong laser fields are in some way relevant to quantum optics. However, the word multiphoton is something of a misnomer in the strong field regime. In fact, if very many photons are involved, quantisation of the radiation field is more or less irrelevant the intense, coherent laser pulse tends to a quasiclassical beam of light. Indeed, it has been pointed out by several authors [483] that the use of the word photon in the context of laser physics is of questionable validity. 

Nonlinear optical processes occur when a medium is subjected to an intense electric field, E, such as that associated with a strong pulse of laser light. The field polarizes the medium. At the molecular level, the change of electronic density distribution creates an induced dipole moment which can be expressed as a power series ... 

A short pulse of strongly absorbed above band gap light (N photons per sample area) creates Nr)<> carriers, n being the primary efficiency for generating geminate e—h pairs and (f(E) their dissociation probability as a function of applied field E. At short times where loss processes are still negligible, the resulting peak photocurrent is... 

---