Cascaded Parametric Amplification for Highly Efficient Terahertz Generation

A highly efficient, practical approach to high-energy terahertz (THz) generation based on spectrally cascaded optical parametric amplification (THz-COPA) is introduced. The THz wave initially generated by difference frequency generation between a strong narrowband optical pump and optical seed (0.1-10% of pump energy) kick-starts a repeated or cascaded energy down-conversion of pump photons. This helps to greatly surpass the quantum-defect efficiency and results in exponential growth of THz energy over crystal length. In cryogenically cooled periodically poled lithium niobate, energy conversion efficiencies >8% for 100 ps pulses are predicted. The calculations account for cascading effects, absorption, dispersion and laser-induced damage. Due to the coupled nonlinear interaction of multiple triplets of waves, THz-COPA exhibits physics distinct from conventional three-wave mixing parametric amplifiers. This in turn governs optimal phase-matching conditions, evolution of optical spectra as well as limitations of the nonlinear process.Comment: 5 pages, double colum

Orthogonal control for stable parallel waveform synthesis

We present a control scheme for parallel optical parametric waveform synthesizers. Orthogonalization of the relative arrival time and relative phase between all individual channels promises to achieve shot-to-shot stable and controlled ultra-broadband pulse synthesis

Temporal Characterization of Front-End for Yb-Based High-Energy Optical Waveform Synthesizers

We demonstrate temporal characterization of the front-end for an Yb-based, passively CEP-stable, two-octave-wide, two-channel optical parametric synthesizer driven by slightly subpicosecondpump pulses from a multi-mJ regenerative amplifier at 1 kHz

High-dynamic-range arrival time control for flexible, accurate and precise parametric sub-cycle waveform synthesis

We introduce a simple all-inline variation of a balanced optical cross-correlator (BOC) that allows to measure the arrival time difference (ATD), over the full Nyquist bandwidth, with increased common-mode rejection and long-term stability. An FPGA-based signal processing unit allows for real-time signal normalization and enables locking to any setpoint with an unprecedented accuracy of 0.07% within an increased ATD range of more than 400 fs, resulting in attosecond resolution locking. The setup precision is verified with an out-of-loop measurement to be less than 80 as residual jitter paving the way for highly demanding applications such as parametric waveform synthesizers

THz-induced Kerr effect in polar liquids

We investigate the THz-field induced orientation of molecules in the liquid state by means of the Kerr effect. In contrast to an optical or near-infrared excitation, THz photons have frequencies below the intramolecular vibrations and therefore leave the internal structure of the molecule mostly unaffected. We find experimental evidence for a THz-induced optical birefringence, which provides evidence for molecular orientation. Experimental data on anethole and water reveal the potential application for molecular re-orientation during ultrafast chemical reactions

Synchronous laser-microwave network for attosecond-resolution photon science

Next-generation photon-science facilities such as X-ray free-electron lasers and intense-laser beamline centers are emerging worldwide with the goal of generating sub-fs Xray pulses with unprecedented brightness to capture ultrafast chemical and physical phenomena with sub-atomic spatiotemporal resolution. A major obstacle preventing this long-standing scientific dream to come true is a high precision timing distribution system synchronizing various microwave and optical sub-sources across multi-km distances. Here, we present, for the first time, a synchronous laser-microwave network providing a timing precision in the attosecond regime. By developing new ultrafast timing detectors and carefully balancing optical fiber nonlinearities, we achieve timing stabilization of a 4.7-km fiber link network with 580-attosecond precision over 52 h. Furthermore, we realize a complete laser-microwave network incorporating two mode-locked lasers and one microwave source with total 950-attosecond jitter integrated from 1 μs to 18 h

Attosecond precision multi-kilometer laser-microwave network

Synchronous laser-microwave networks delivering attosecond timing precision are highly desirable in many advanced applications, such as geodesy, very-long-baseline interferometry, high-precision navigation and multi-telescope arrays. In particular, rapidly expanding photon-science facilities like X-ray free-electron lasers and intense laser beamlines require system-wide atto-second-level synchronization of dozens of optical and microwave signals up to kilometer distances. Once equipped with such precision, these facilities will initiate radically new scienceby shedding light on molecular and atomic processes happening on the attosecond timescale, such as intramolecular charge transfer, Auger processes and their impacts on X-ray imaging.Here we present for the first time a complete synchronous laser-microwave network with attosecond precision, which is achieved through new metrological devices and careful balancing offiber nonlinearities and fundamental noise contributions. We demonstrate timing stabilization of a 4.7-km fiber network and remote optical–optical synchronization across a 3.5-km fiber link with an overall timing jitter of 580 and 680 attoseconds root-mean-square, respectively, for over 40 h. Ultimately, we realize a complete laser-microwave network with 950-attosecond timing jitter for 18 h. This work can enable next-generation attosecond photon-science facilities to revolutionize many research fields from structural biology to material science and chemistry to fundamental physics