Cherenkov Radiation from Femtosecond Optical Pulses in Electro-Optic Media

Auston, D. H.; Cheung, K. P.; Valdmanis, J. A.; Kleinman, D. A.

doi:10.1103/physrevlett.53.1555

Cited by 611 publications

(254 citation statements)

References 6 publications

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“…The same property should also give rise to functionally more relevant frequency downconversion ( 30) or optical rectification (26). This phenomenon has been observed in noncentrosymmetric semiconductors (27)(28)(29)(30) and organic crystals (31) in the form of single-cycle radiation in the THz and midinfrared region as a response to ultrashort laser pulses but not in biological materials. On the other hand, long-lasting coherent infrared emission has been observed from heme protein crystals (32), originating solely from the vibrational response of the protein.…”

mentioning

confidence: 99%

Resonant optical rectification in bacteriorhodopsin

Groma

Colonna

Lambry

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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The relative role of retinal isomerization and microscopic polarization in the phototransduction process of bacteriorhodopsin is still an open question. It is known that both processes occur on an ultrafast time scale. The retinal trans3cis photoisomerization takes place on the time scale of a few hundred femtoseconds. On the other hand, it has been proposed that the primary lightinduced event is a sudden polarization of the retinal environment, although there is no direct experimental evidence for femtosecond charge displacements, because photovoltaic techniques cannot be used to detect charge movements faster than picoseconds. Making use of the known high second-order susceptibility (2) of retinal in proteins, we have used a nonlinear technique, interferometric detection of coherent infrared emission, to study macroscopically oriented bacteriorhodopsin-containing purple membranes. We report and characterize impulsive macroscopic polarization of these films by optical rectification of an 11-fs visible light pulse in resonance with the optical transition. This finding provides direct evidence for charge separation as a precursor event for subsequent functional processes. A simple two-level model incorporating the resonant second-order optical properties of retinal, which are known to be a requirement for functioning of bacteriorhodopsin, is used to describe the observations. In addition to the electronic response, long-lived infrared emission at specific frequencies was observed, reflecting charge movements associated with vibrational motions. The simultaneous and phase-sensitive observation of both the electronic and vibrational signals opens the way to study the transduction of the initial polarization into structural dynamics.R etinal proteins play an essential role in a broad range of light-driven biological processes, including vision (1), energy transduction (2), and circadian control (3). All these functions involve both the conversion of light energy into charge separation and retinal isomerization, but the interplay of these processes is the subject of intense debate. The retinal protein of which the initial photochemistry is most extensively studied is the photosynthetic protein bacteriorhodopsin (bR). This protein colors the purple membrane of halobacteria and acts as a light-driven proton pump by means of a multistep process termed the photocycle (2). In the traditional model for the initial transduction step in this cycle is directly light-driven trans3cis isomerization of retinal (4-6); this model has been recently extended by including excited-state skeletal stretching (5, 7). However, experiments with modified bR containing nonisomerizable retinal analogs challenged this model by showing that the initial photo-induced events are not associated with retinal isomerization (8-10). In fact, in an early alternative hypothesis (11), the essential process was proposed to be dielectric relaxation of the protein as a response to sudden polarization upon retinal excitation (11-13). Recent molecular dynamic...

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mentioning

confidence: 99%

Resonant optical rectification in bacteriorhodopsin

Groma

Colonna

Lambry

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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“…Relative energies of the modes were chosen as δ Ω = −3 meV and δ J = 1 meV, the latter corresponding to an applied electric field of magnitude F = 0.945F 0 , where F 0 = 12.5 kV/cm is the field strength at which the DX and IX modes are resonant. 42 Performing numerically the stability analysis of solutions of Eqns. (6) and (7) allows us to plot a phase diagram of the system shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Continuous terahertz emission from dipolaritons

et al. 2013

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We propose a scheme of continuous tunable THz emission based on dipolaritons -mixtures of strongly interacting cavity photons and direct excitons, where the latter are coupled to indirect excitons via tunnelling. We investigate the property of multistability under continuous wave (CW) pumping, and the stability of the solutions. We establish the conditions of parametric instability, giving rise to oscillations in density between the direct exciton and indirect modes under CW pumping. In this way we achieve continuous and tunable emission in the THz range in a compact single-crystal device. We show that the emission frequency can be tuned in a certain range by varying an applied electric field and pumping conditions. Finally, we demonstrate the dynamic switching between different phases in our system, allowing rapid control of THz radiation.

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“…In general, this surface is of an electro-optic material that lacks inversion symmetry and should therefore be expected to produce a THz signal via optical rectification. 6 In fact, if the wafer is diced ͑or cleaved͒ along the proper axis one may reveal the ͑110͒ plane, which has been previously exploited for THz generation via optical rectification. 7,8 The spectra in Fig.…”

Section: School Of Electrical and Computer Engineeringmentioning

confidence: 99%

Parallel plate THz transmitter

Coleman

Grischkowsky

2004

Applied Physics Letters

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A THz transmitter that directly excites the guided wave modes of a dielectric filled parallel plate waveguide is demonstrated. When coupled to free space, the transmitter yields a large peak time-domain THz signal. The device yields significant signal amplitudes with varying output spectra with and without a bias field applied. This transmitter provides powerful direct excitation of guided wave modes and is the next step toward an integrated guided wave transverse-electromagnetic mode THz bandwidth device.

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Cherenkov Radiation from Femtosecond Optical Pulses in Electro-Optic Media

Cited by 611 publications

References 6 publications

Resonant optical rectification in bacteriorhodopsin

Resonant optical rectification in bacteriorhodopsin

Continuous terahertz emission from dipolaritons

Parallel plate THz transmitter

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