Conversion of short optical pulses to terahertz radiation in a nonlinear medium: Experiment and theory

Abstract

Publisher's copyright statement:Reprinted with permission from the American Physical Society: Zinov'ev, N., Nikoghosyan, A.S., Dudley, R.A. Chamberlain, J.M. (2007). Conversion of short optical pulses to terahertz radiation in a nonlinear medium: Experiment and theory. Physical Review B 76(23): 235114. c 2007 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society. Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We report on the frequency and time domain analysis of electromagnetic terahertz radiation generated by nonlinear conversion of short optical pulses crossing boundaries of nonlinear material. Analysis and comparison with experiment have unequivocally established that the nature of collinear radiation at terahertz frequencies relates to the phenomenon of transition radiation produced by the instantaneous creation ͑at the input interface͒ and extinction ͑at the output interface͒ of the moving polarization charge formed by the nonlinear coupling of the pump electromagnetic fields. The mechanism is analogous to the phenomena of transition radiation of moving free charges, in particular, to the radiation mechanism discussed in the Tamm problem.

Comment on “Terahertz Radiation from a Nonlinear Slab Traversed by an Optical Pulse”

“…The criticism in the present Comment applies analogously to a later article by the same authors [5]. The additional arguments given there are not substantive either for the same reasons.…”

“…Hence the proportionality of the emitted waves (6) and (7) to L FW coh follows naturally from the NLWC model. Note also that the general solution (5) can easily be generalized to v g < c 0 =n. In this case, the third term in (5)-the so-called ''inhomogeneous wave'' (IHW)-changes its sign, which is straightforward for interfering free waves in NLWC, but disproves the description in [1] that this term was the nonradiative ''field of the polarization charge.''…”

GENERATION OF THz RADIATION IN NONLINEAR CRYSTAL PARTIALLY FILLING A HOLLOW WAVEGUIDE

“…Increasing conversion efficiency in the order of magnitude has been obtained in waveguide partially filled with LiNbO 3 compared to the crystal placed in a free space 17 . At phase matching in waveguide efficiency energy of nonlinear conversion compared to mismatching is increased ~ 50 times.…”

Terahertz Generation in an Electrically Biased Optical Fiber: A Theoretical Investigation

“…Techniques to generate CW THz waves include quantum cascade laser (QCL) [5], directly multiplied source [6], backward wave oscillator (BWO) [7], germanium laser [8], and silicon impurity state laser [9]. Similarly, techniques to generate pulsed THz waves include nonlinear optical source (which can also be utilized to generate CW THz waves) [10], optically pumped THz laser [11], and free electron laser [12]. THz generation based on a QCL is realized based on intersubband transitions in quantum wells.…”