Using longer wavelength laser drivers for high harmonic generation is desirable because the highest extreme ultraviolet frequency scales as square of wavelength. Recent numerical studies predict that efficiency falls dramatically with increasing wavelength, a very unfavorable lambda(-(5-6)) scaling. We performed an experimental study yield over range 800-1850 nm. A thin gas jet was employed to minimize phase matching effects, and intensity focal spot size were kept constant changed. Ion...

High-harmonic spectroscopy probes atomic structure by looking at the short-wavelength emission excited from atoms ultrafast pulses of laser light. It is now shown that this technique can even detect signatures electron–electron interactions. provides a unique insight into electronic and molecules1,2,3,4,5. Although attosecond science holds promise accessing timescale interactions, until now, their signature has not been seen in high-harmonic spectroscopy. We have recorded spectra to beyond...

Tunneling, one of the most striking manifestations quantum mechanics, influences electronic structure many molecules and solids is responsible for radioactive decay. Much interaction intense light pulses with matter commences electrons tunneling from atoms or to continuum. Until recently, this starting point was assumed be highest occupied orbital a given system. We have now observed lower-lying state in hydrogen chloride (HCl). Analyzing two independent experimental observables allowed us...

We demonstrate a simple scheme to generate 0.4 mJ 11.5 fs laser pulses at 1.8 μm. Optical parametrically amplified are spectrally broadened by nonlinear propagation in an argon-filled hollow-core fiber and subsequently compressed 1.9 optical cycles linear through bulk material the anomalous dispersion regime. This pulse compression is confirmed numerical simulations.

We demonstrate a polarization-managed 8-dimensional modulation format that is time domain coded to reduce inter-channel nonlinearity. Simulation results show 2.3 dB improvement in maximum net system margin (NSM) relative polarization multiplexed (PM)-BPSK, and 1.0 interleaved return-to-zero (RZ)-PM-BPSK, for five WDM channels propagating over 1600 km ELEAF with 90% inline optical dispersion compensation. In contrast the other modulations considered, new has negligible sensitivity states of...

By using the novel approach for pulse compression that combines spectral broadening in hollow-core fiber (HCF) with linear propagation fused silica (FS), we generate 1.6 cycle 0.24 mJ laser pulses at 1.8 μm wavelength a repetition rate of 1 kHz. These are obtained white light seeded optical parametric amplifier (OPA) and shown to be passively carrier envelope phase (CEP) stable.

We report the extension of hollow-core fibre pulse compression to longer wavelengths.High-energy multi-cycle infrared pulses are generated via optical parametric amplification and subsequently broadened in fibre.2.5-cycle at Signal wavelength (1.4 μm) 1.6-cycle Idler (1.8 sub-millijoule regime have been generated.New schemes can be applied 1.8 μm beyond.In this manner, carrier envelope phase stable were by linear propagation anomalous dispersion bulk glass which surprisingly enables below...

A number of optical frequency standards have been evaluated with fractional uncertainties between ${10}^{\ensuremath{-}17}$ and ${10}^{\ensuremath{-}18}$. Reduction the statistical uncertainty a clock comparison to this level is challenging, requiring best possible stability avoid excessively long averaging times. We report recent improvements our $^{88}\mathrm{Sr}{}^{+}$ single-ion standard that reduced its 1-s Allan deviation from...

High harmonic spectroscopy utilizes the methods of attosecond science to study electronic properties atoms and molecules. We use a 1.8 µm 11 fs laser source generate high spectra beyond 150 eV. The Cooper minimum in krypton is clearly visible these spectra, would otherwise be difficult observe with 800 nm sources. relate shape spectrum photoionization cross section krypton.

We present enhanced modulation formats optimized for nonlinear performance over a range of spectral efficiency. Maximum transmission distance is improved by > 600 km at PM-8QAM capacity and 3500 PM-BPSK rates.

We report generation of 400 microJ, 13.1 fs, 1425 nm optical parametric amplifier laser pulses. Spectral broadening a 100 Hz source is achieved by self-phase modulation in an argon-filled hollow-core fiber, and dispersion compensation performed using chirped mirrors. This will be useful for ultrafast time-resolved molecular orbital tomography.

A method for in-service OSNR measurement with a coherent transceiver is presented and experimentally verified. neural network employed to identify remove the nonlinear noise contribution estimated OSNR.

High harmonic generation in gas targets leads to the production of attosecond pulses. The process high requires that be ionized by an intense femtosecond laser field. highest photon energy produced is related intensity times wavelength squared. This cutoff reached only if good phase matching achieved. Using a with 1800 nm, we estimate jet recording ion yield, and simultaneously record spectrum. We show matches measured intensity, confirming achieved 100 eV. also use collector characterize...

We present experimental results showing the appearance of a near-continuum in high-order harmonic generation (HHG) spectra atomic and molecular species as driving laser intensity an infrared pulse increases. Detailed macroscopic simulations reveal that these are capable producing IAPs far field if proper spatial filter is applied. Further, our show product strong temporal reshaping (blue shift defocusing) field. This offers possibility with broad range photon energy, including plateau...

Numerous applications of high harmonic generation (HHG), such as attosecond pulse synthesis, depend on the ability to increase electron recollision energy, which is a quadratic function driver wavelength.High-energy infrared pulses obtained from an optical parametric amplifier (OPA) are thus attractive for driving HHG process, thereby offering opportunity yield shorter pulses.However, in wavelength often outweighed by poor spatial quality OPA source.In this paper, we demonstrate that using...

Signal processing techniques for mitigating intra-channel and inter-channel fiber nonlinearities are reviewed. More detailed descriptions of three specific examples highlight the diversity electronic optical approaches that have been investigated.

The present decade has seen great advances in optical frequency standards following the development of femtosecond laser combs. With this technology, combined with a stable and narrow probe source (50-100 Hz linewidth), we made systematic study 5<i>s</i> ²<i>S</i>_1/2-4<i>d</i> ²<i>D</i>_5/2 (S-D) transition ⁸⁸Sr⁺ ion as function quantization axis trap. This revealed presence shifts caused by residual micromotion our rf Paul...

The electrostriction nonlinearity in a standard single mode fiber is measured by cross-phase modulation (XPM) between pump and probe. Novel use of coherent homodyne receiver allows measurement in-phase quadrature components the probe field, eliminating need for an optical interferometer. Kerr effect ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math>$\gamma _{k}$</tex-math></inline-formula> ) frequency-dependent...

The electric quadrupole shift is an important source of systematic uncertainty in several single-ion optical frequency standards. In this paper, we review the cancellation method based on Zeeman spectrum clock transition. demonstrated with actual measurement 5s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> S <sub xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sub> -4d D xmlns:xlink="http://www.w3.org/1999/xlink">5/2</sub> transition...

We characterize the performance of 4- and 8-dimensional formats vs. spectral efficiency. Optimized 4D polarization-balanced 8D improve system margin by > 0.5 dB on dispersion-uncompensated 1.2 dispersion-managed networks.