Transcript Slides - Jung Y. Huang

Freezing phase scheme for complete-field
characterization and coherent control of femtosecond
optical pulses
Jung Y. Huang, Ci L. Pan, and J. I. Chyi
An attractive scheme to control and steer the quantum states
of a complex system is adaptive laser pulses control. This
concept appears to be universal and recent progress had
indicated that the purpose of coherent control study is not only
to control the evolution of a complex system but also to
deduce the detailed dynamic mechanism from the optimal
laser field used.
Control of a Material System with Ultrashort Light
 Go beyond the simple pump-probe spectroscopic techniques by using the laser
pulses to influence the course of the molecular dynamics.
 This kind of work is usually carried out in a feedback loop with some form of pulse
shaping element controlled by a computer.
 An issue with coherent control is the inverse problem, i.e. how to retrieve
information about the system dynamics from the known optimal pulse.
 The core techniques are needed: (1) characterize ultrafast pulses; and (2) modify
them appropriate to the experiments.
Complete-field characterization of coherent optical pulses
The freezing phase algorithm can directly and rapidly yield
complete-field information.
 Both profiles of the magnitude and spectral phase of a
coherent optical pulse can be determined.

Complete-field characterization of coherent optical pulses:
with freezing phase scheme
Complete-field characterization of coherent
optical pulses with SHG-FROG: a comparison
(2) Coherent-controlled nonlinear optical microscopy
 Coherent control contrast enhancement as large as a
factor of three can be achieved at regions where the PL peak
wavelengths differ only 18 nm.
Input pulses
spectrometer
Beam splitter
Objective
lens
SLM
sample
XY scanning stage
Coherent-controlled nonlinear optical microscopy
 Coherent control offers an additional degree of
freedom for distinguishing coherent and incoherent
nonlinear optical processes.