TheKramers-Kronigrelationsconstitutethemathematicalformulationofthe
fundamental connection between the in-phase to the out-of-phase response
of a system to a sinusoidal time-varying external perturbation. Such
connection exists in both classical and quantum physical systems and
derives directly from the principle of causality. Apart from being of
great importance in high energy physics, statistical physics, and
acoustics, at present the Kramers-Kronig relations are basic and
widely-accepted tools for the investigation of the linear optical
properties of materials, since they allow performing the so-called
inversion of optical data, i.e. acquiring knowledge on dispersive
phenomena by measurements of absorptive phenomena over the whole energy
spectrum or vice versa. Since the late '80s, a growing body of
theoretical results as well as of experimental evidences has shown that
the Kramers-Kronig relations can be adopted for e?ciently acquiring
knowledge on nonlinear optical phenomena. These results suggest that the
Kramers-Kronig relations may become in a near future standard techniques
in the context of nonlinear spectroscopy.
Thisbookisthe?rstcomprehensivetreatisedevotedtoprovidingauni- ing
picture of the physical backgrounds, of the rigorous mathematical
theory, and of the applications of the Kramers-Kronig relations in both
?elds of l- ear and nonlinear optical spectroscopy. Some basic programs
written for the 1 MATLAB environment are also included. This book is
organized as an argumentative discourse, progressing from the linear to
the nonlinear phenomena, from the general to the speci?c s- tems, and
from the theoretical to the experimental results.
