Two-dimensional ultrafast pulse shaping and its application to coherent control and spectroscopy

This thesis develops powerful new methods for shaping femtosecond laser pulses in two dimensions and explores their application to coherent control of propagating lattice excitations and degenerate four-wave mixing spectroscopy. Pulse shaping in two dimensions is achieved by manipulating the spectral components of ultrashort laser pulses within many horizontal slices of the pulse. Each horizontal slice is independently shaped by means of a two-dimensional liquid crystal spatial light modulator, and taken together the shaped regions form sophisticated optical waveforms with time-dependent spatial profiles. Automated optical control over coherent lattice responses that are both time- and position-dependent across macroscopic length scales is demonstrated. Two- dimensional (2D) femtosecond pulse shaping was used to generate excitation light fields that were directed toward distinct regions of crystalline samples, producing terahertz-frequency lattice vibrational waves that emanated outward from their multiple origins at lightlike speeds. Interferences among the waves resulted in fully specified far-field responses, including tilted, focusing, or amplified wavefronts. Generation and coherent amplification of terahertz travelling waves and terahertz phased-array generation are also demonstrated. A novel approach to coherent nonlinear optical spectroscopy based on 2D femtosecond pulse shaping is introduced. Multiple phase-stable output beams are created and overlapped at the sample in a phase-matched boxcars geometry via 2D femtosecond pulse shaping.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Vaughan, Joshua Charles

Advisor dc:contributor.advisor

• Keith A. Nelson.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/32492

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/32492