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 SLM Grating spectrometer Objective lens sample Beam splitter XY scanning stage Input pulses  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.

Coherent-controlled nonlinear optical microscopy  Coherent control offers an additional degree of freedom for distinguishing coherent and incoherent nonlinear optical processes.