Seminar on
Modern Optics and Spectroscopy


János Hebling, MIT

Generation and application of high field THz pulses

April 17, 2007

12:00 noon - 1:00 p.m. Grier Room 34-401

Abstract:

During the last two decades the fast development of time domain THz spectroscopy (TDTS) created a renaissance of this field and related applications of near-single-cycle THz pulses.  Although the majority of TDTS  work has been done by THz pulses having ralatively small energy on the fJ – pJ range there exists a strong and yet unmet need for high energy ultrashort THz pulses for applications in imaging, security control and nonlinear THz spectroscopy. For this purpose in the last few years we developed an efficient THz pulse generation technique based on optical rectification of ultrashort near-IR pump pulses in lithium niobate (LN) crystal. This method achieves matching of the effective pump pulse group velocity to the phase velocity of the THz pulses by so called tilted-pulse-front-excitation. After describing the principle, the set-up and the results achieved by this technique a few of our preliminary nonlinear THz optics and spectroscopy results will be presented. The possible combination of the tilted-pulse-front-excitation with shaped pump pulses will also be sketched. The latter was earlier used at MIT for generation, coherent addition and control of phonon-polaritons (mixture of THz electromagnetic field and lattice vibration) in ferroelectrics (i.e. LN). The combination of the two techniques will enable the generation of high energy THz pulses for (quantum) control experiments with practically arbitrary pulse shape if the spectrum is on the 0.1 – 2 THz range and the pulse duration shorter than 10 ps

TUESDAYS, 12:00-1:00, GRIER ROOM (34-401)
Refreshments served following the seminar

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Co-sponsored by the George R. Harrison Spectroscopy Laboratory,
the Department of Electrical Engineering and Computer Science and
the School of Science, Massachusetts Institute of Technology.