Cascaded interactions mediated by terahertz radiation

Hemmer, Michaël; Cirmi, Giovanni; Ravi, Koustuban; Reichert, Fabian; Ahr, Frederike; Zapata, Luis E.; Mücke, Oliver D.; Calendron, Anne-Laure; Çankaya, Hüseyin; Schimpf, Damian N.; Matlis, Nicholas H.; Kärtner, Franz X.

doi:10.1364/oe.26.012536

Cited by 21 publications

(17 citation statements)

References 21 publications

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“…6(a)-6(d), the spectrum shows an increasing red-shift with distance, accompanied also with some blue-shift due to symmetry in the phase matching of sum and difference frequency generation that results from the small value of the terahertz frequency. This is similar to that observed in [59,60].…”

Section: Cascading Effectssupporting

confidence: 90%

Simultaneous generation and compression of broadband terahertz pulses in aperiodically poled crystals

Ravi¹,

Kärtner²

2019

Opt. Express

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We introduce a technique to generate compressed broadband terahertz pulses based on cascaded difference-frequency generation. The approach employs a non-uniform sequence of pump pulses in aperiodically poled crystals. The pump-pulse format and poling of crystals conceived are such that the emergent terahertz pulse is already compressed. The method circumvents pump-pulse distortions that result from non-collinear approaches and the need for external compression. While capable of generating even single-cycle pulses, it is particularly efficient for the generation of pulses with few to tens-of-cycles duration. For instance, calculations accounting for cascading effects predict conversion efficiencies in the few percent range for cryogenically-cooled lithium niobate. The focused electric fields are 100 MV/m in free space.

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Section: Cascading Effectssupporting

confidence: 90%

Simultaneous generation and compression of broadband terahertz pulses in aperiodically poled crystals

Ravi¹,

Kärtner²

2019

Opt. Express

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“…For the case of cascaded optical parametric amplification,

N_{w} \approx 1

and therefore

{d false⟨ ω false⟩ / d z |}_{z = 0} \approx 0

, which is consistent with refs. [12, 13]. In fact, simulating different input pump spectra using Equation () predicts effects which are qualitatively identical to a direct numerical solution of Equations () and () (Supporting Information).…”

Section: Analytic Proof Of Raman Shiftingmentioning

confidence: 55%

“…In contrast, another class of cascaded second‐order nonlinearities occur when a large number of highly phase‐matched second‐order processes evolve in concert. This is of great interest to terahertz generation, [ 10–14 ] where the repeated energy down‐conversion of an optical or near infrared (NIR) pump photon to multiple terahertz photons via cascaded difference‐frequency generation (DFG) was proposed to surmount the single‐photon conversion efficiency or Manley‐Rowe limit. [ 15 ] The approach has already resulted in the highest optical‐to‐terahertz energy conversion efficiencies [ 16,17 ] to date.…”

Section: Introductionmentioning

confidence: 99%

Raman Shifting Induced by Cascaded Quadratic Nonlinearities for Terahertz Generation

Ravi

Kärtner

2020

Laser & Photonics Reviews

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Cascaded quadratic optical nonlinearities are well known for producing effective third-order nonlinear optical effects such as self-phase modulation or self-steepening. As a result, they have been extensively applied in areas such as mode-locking and pulse compression. In this article, a regime of cascaded quadratic nonlinearities involving highly phase-matched second-order interactions is introduced, which produce an effective third-order nonlinearity analogous to Raman shifting rather than the typical case of self-phase modulation. This results in a continuous red-shift of the optical pump frequency rather than spectral broadening. This phenomenon is particularly relevant to terahertz generation, where a continuous red-shift of the pump frequency resolves current issues of dispersion and laser-induced damage. In the absence of absorption or dispersion, the presented method results in optical-to-terahertz energy conversion efficiencies that approach 100%, which is not possible with conventional cascaded difference-frequency generation. Designs of aperiodically poled lithium niobate structures are presented, which result in energy conversion efficiencies of 35% even in the presence of dispersion and absorption. The presented work thus addresses an important bottleneck in terahertz generation, which paves the way for the development of compact particle accelerators, X-ray free-electron lasers, advanced electron-beam diagnostics, and various experiments in condensed-matter physics and chemistry.

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“…Future efforts will primarily focus on the generation of a laser output comprising multiple lines. As explained in [17,36], a coherent superposition of multiple lines increases the conversion efficiency for multi-cycle terahertz generation. The multiple lines can be generated from the present system by coupling the front-end's output into a nonlinear fiber.…”

Section: Resultsmentioning

confidence: 99%

Frequency-comb-based laser system producing stable optical beat pulses with picosecond durations suitable for high-precision multi-cycle terahertz-wave generation and rapid detection

Schimpf¹,

Olgun²,

Kalaydzhyan³

et al. 2019

Opt. Express

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We generate temporally modulated optical pulses with a beat frequency of 255 GHz, a duration of 360 ps, and a repetition rate of 2 MHz. The temporal envelope, beat frequency, and repetition rate are computer-programmable. A frequency comb serves as a phase and frequency reference for the locking of two laser lines. The system enables beat frequencies that are adjustable in steps of the frequency comb's repetition rate and exhibit Hzlevel precision and accuracy. We expect the optical beat pulses to be well suited for versatile multi-cycle terahertz-wave generation with controllable carrier-envelope phase. We demonstrate that the inherent synchronization of the frequency comb's ultra-short pulse train and the synthesized optical beat (or later the multi-cycle terahertz) pulses enables rapid and phase-sensitive sampling of such pulses.

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Cascaded interactions mediated by terahertz radiation

Cited by 21 publications

References 21 publications

Simultaneous generation and compression of broadband terahertz pulses in aperiodically poled crystals

Simultaneous generation and compression of broadband terahertz pulses in aperiodically poled crystals

Raman Shifting Induced by Cascaded Quadratic Nonlinearities for Terahertz Generation

Frequency-comb-based laser system producing stable optical beat pulses with picosecond durations suitable for high-precision multi-cycle terahertz-wave generation and rapid detection

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