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Main Authors: Rentschler, Christian, Matlis, Nicholas H., Demirbas, Umit, Zhang, Zhelin, Nitzsche, Jonas, Ravi, Koustuban, Pergament, Mikhail, Kärtner, Franz X.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.20118
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author Rentschler, Christian
Matlis, Nicholas H.
Demirbas, Umit
Zhang, Zhelin
Nitzsche, Jonas
Ravi, Koustuban
Pergament, Mikhail
Kärtner, Franz X.
author_facet Rentschler, Christian
Matlis, Nicholas H.
Demirbas, Umit
Zhang, Zhelin
Nitzsche, Jonas
Ravi, Koustuban
Pergament, Mikhail
Kärtner, Franz X.
contents High-energy (mJ) and high-peak-power (MW) multicycle terahertz (THz) pulses are essential for nonlinear THz spectroscopy and compact accelerator technologies, yet their generation by nonlinear optical frequency conversion remains inefficient and imposes severe demands on femtosecond driving lasers. Amplifying existing THz pulses offers an appealing alternative, but no power-scalable amplifier has been realized in the sub-THz regime. Here, we demonstrate an all-optical THz amplifier operating at 0.35 THz based on the modulation of nanosecond laser pulses by a weak THz field in periodically poled lithium niobate (PPLN). The THz-induced phase modulation is converted into an amplitude modulation using controlled group delay dispersion, forming a tailored pulse train that can efficiently drive high-energy THz generation in a second crystal, thereby amplifying the THz seed. By analogy to electronic klystrons, we term this device the Phlystron, in which the electron beam carrying the power is replaced by a photon beam. In this proof-of-concept experiment, a 3.3-fold increase in THz energy is achieved with commercial crystals. Scaling analysis indicates the potential for higher gain when using large-aperture PPLN devices and multi-stage amplification. The Phlystron thus provides a scalable route to powerful multicycle THz sources driven by readily available narrowband lasers.
format Preprint
id arxiv_https___arxiv_org_abs_2605_20118
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Phlystron -- A photonic terahertz amplifier
Rentschler, Christian
Matlis, Nicholas H.
Demirbas, Umit
Zhang, Zhelin
Nitzsche, Jonas
Ravi, Koustuban
Pergament, Mikhail
Kärtner, Franz X.
Optics
High-energy (mJ) and high-peak-power (MW) multicycle terahertz (THz) pulses are essential for nonlinear THz spectroscopy and compact accelerator technologies, yet their generation by nonlinear optical frequency conversion remains inefficient and imposes severe demands on femtosecond driving lasers. Amplifying existing THz pulses offers an appealing alternative, but no power-scalable amplifier has been realized in the sub-THz regime. Here, we demonstrate an all-optical THz amplifier operating at 0.35 THz based on the modulation of nanosecond laser pulses by a weak THz field in periodically poled lithium niobate (PPLN). The THz-induced phase modulation is converted into an amplitude modulation using controlled group delay dispersion, forming a tailored pulse train that can efficiently drive high-energy THz generation in a second crystal, thereby amplifying the THz seed. By analogy to electronic klystrons, we term this device the Phlystron, in which the electron beam carrying the power is replaced by a photon beam. In this proof-of-concept experiment, a 3.3-fold increase in THz energy is achieved with commercial crystals. Scaling analysis indicates the potential for higher gain when using large-aperture PPLN devices and multi-stage amplification. The Phlystron thus provides a scalable route to powerful multicycle THz sources driven by readily available narrowband lasers.
title Phlystron -- A photonic terahertz amplifier
topic Optics
url https://arxiv.org/abs/2605.20118