40-µJ passively CEP-stable seed source for ytterbium-based high-energy optical waveform synthesizers

Çankaya, Hüseyin; Calendron, Anne-Laure; Zhou, Chun; Chia, Shih Hsuan; Mücke, Oliver D.; Cirmi, Giovanni; Kärtner, Franz X.

doi:10.1364/oe.24.025169

Cited by 24 publications

(26 citation statements)

References 36 publications

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“…The quantitative model presented provides a key tool for designing the next generation of low-noise CEP-stable OP(CP)A-based sources. good levels of stability [7,8]. However, in order to reach high pulse energies, OP(CP)A systems have grown in size and complexity, entailing an increase in the timing jitter among the different amplification stages.…”

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confidence: 99%

CEP dependence of signal and idler upon pump-seed synchronization in optical parametric amplifiers

Rossi¹,

Wang²,

Mainz³

et al. 2018

Opt. Lett.

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We study the effect of pump-seed timing fluctuations on the carrier-envelope phase (CEP) of signal and idler pulses emerging from an OP(CP)A. A simple analytical model is derived in order to provide an intuitive explanation of the origin of CEP fluctuations, while split-step simulations are performed to cover a broad range of different seeding schemes. Finally, we compare the simulation results with real observations of the CEP of idler pulses generated by an OPA. The quantitative model presented provides a key tool for designing the next generation of low-noise CEP-stable OP(CP)A-based sources. good levels of stability [7,8]. However, in order to reach high pulse energies, OP(CP)A systems have grown in size and complexity, entailing an increase in the timing jitter among the different amplification stages.In this Letter, we intend to clarify the influence of pumpseed timing fluctuations on the CEP of both signal and idler pulses emerging from an OP(CP)A. We analyze two of the most significant schemes: generation of a CEP-stable idler and amplification of a broadband stretched signal successively compressed.We start by considering the system of three coupled equations [9], which describes parametric amplification along the propagation direction, within the approximation of monochromatic plane waves and perfect phase matching. The parametric amplification process is maximized when the generalized phase Φ ϕ p − ϕ s − ϕ i is equal to π∕2 [10], in other words ϕ i ϕ p − ϕ s − π∕2. It is worth noting that the phase ϕ k (k p; s; i), represents the absolute phase (AP) of each wave, that is, the phase with respect to the lab reference frame and not the CEP of the corresponding pulses. To analytically determine the CEP of the signal and idler pulses generated in an OPA, it would be necessary to solve the aforementioned coupled equation system while considering the time dependency of the amplitude envelope of each pulse and the effect of dispersion. Unfortunately, no analytic solutions have been found in this case. However, within certain limits, it is still possible to describe analytically the effect of the pump-seed timing fluctuations on the CEP of signal and idler.Consider a white-light (WL) seeded OPA or any other parametric amplifier where the seed has been produced starting from a portion of the pump pulse via a coherent process, i.e., the seed pulse has inherited the AP from the pump pulse. During the spectral broadening, an additional term is added to the phase of the seed, but we will not consider it because such phase term has no dependence on timing fluctuations but rather on intensity fluctuations, whose effects on CEP goes beyond the scope of this paper. For small pump-seed relative arrival time fluctuations ΔT compared with the pump pulse Full control of the electric field of an ultrashort laser pulse is necessary to precisely control light-matter interaction processes happening on femtosecond (fs) and attosecond (as) time scales [1][2][3]. To describe the time-dependence of the electric field of a laser pu...

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CEP dependence of signal and idler upon pump-seed synchronization in optical parametric amplifiers

Rossi¹,

Wang²,

Mainz³

et al. 2018

Opt. Lett.

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“…Currently, the main limitation is the narrow seed spectrum available. Future work will focus on development of higher power and higher energy sub-250-femtosecond Yb:YLF amplifiers, for applications such as pumping of high energy and average power optical parametric amplifiers [42], spectral broadening and compression of high energy pulses and ultrafast x-ray generation [43,44].…”

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confidence: 99%

20-mJ, sub-ps pulses at up to 70 W average power from a cryogenic Yb:YLF regenerative amplifier

et al. 2020

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We report, what is to our knowledge, the highest average power obtained directly from a Yb:YLF regenerative amplifier to date. A fiber front-end provided seed pulses with an energy of 10 nJ and stretched pulsewidth of around 1 ns. The bow-tie type Yb:YLF ring amplifier was pulse pumped by a kW power 960 nm fiber coupled diode-module. By employing a pump spot diameter of 2.1 mm, we could generate 20-mJ pulses at repetition rates between 1 Hz and 3.5 kHz, 10 mJ pulses at 5 kHz, 6.5 mJ pulses at 7.5 kHz and 5 mJ pulses at 10 kHz. The highest average power (70 W) was obtained at 3.5 kHz operation, at an absorbed pump power level of 460 W, corresponding to a conversion efficiency of 15.2%. Despite operating in the unsaturated regime, usage of a very stable seed source limited the power fluctuations below 2% rms in a 5 minute time interval. The output pulses were centered around 1018.6 nm with a FWHM bandwidth of 2.1 nm, and could be compressed to below 1-ps pulse duration. The output beam maintained a TEM 00 beam profile at all power levels, and possesses a beam quality factor better than 1.05 in both axis. The relatively narrow bandwidth of the current seed source and the moderate gain available from the single Yb:YLF crystal was the main limiting factor in this initial study. a gain bandwidth of 10 nm for the E//a axis at cryogenic temperatures [1]. Moreover, unlike Yb:YAG, the emission profile is rather smooth, which minimizes gain-narrowing effects, that could potentially enable amplification of sub-250 fs long pulses. At the same time, parameters of Yb:YLF such as thermal conductivity, thermal expansion coefficient, thermo-optic coefficient (dn/dT) are better than for RT Yb:YAG. On the other hand, the emission cross section of Yb:YLF at 80 K is only around 0.7 × 10 −20 cm 2 for the E//a axis, which is around 3 times lower than RT-Yb:YAG and 14 times lower when compared to cryogenic Yb:YAG. However, the longer fluorescence lifetime, τ=1990 µs [17], partly balances for the reduced gain, resulting in a σ em τ-product of 1.4 x10 −23 cm 2 s in comparison with 2 × 10 −23 cm 2 s and 9.4 × 10 −23 cm 2 s of RT and cryogenic Yb:YAG, respectively. As a result of the low emission cross section, one also suffers from a rather high saturation fluence (14 J/cm 2 ) in Yb:YLF, which creates challenges in optimizing extraction from amplifiers. As an example, for a stretched pulsewidth of 1 ns, the cavity optics has an estimated laser induced damage threshold (LIDT) of around 6.3 J/cm 2 , and long-term damage free operation usually requires operating the amplifier at a lower/safer value of ∼3 J/cm 2 or below. Operating the amplifier at a fluence value much lower than the saturation fluence: (i) reduces the extraction efficiency of the circulating amplified pulse, (ii) increases output energy fluctuations upon undesired perturbations, and (iii) results in circulation of a Gaussian beam profile in the amplifier (which is known to have 2 times higher fluence compared to flattop beams). Note that, despite these disadvantages, if the am...

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“…White-light generation, first observed in 1970 [1] and later investigated experimentally and theoretically [2], is currently extensively used in ultrafast laser systems, for example for spectroscopy or to seed optical parametric amplifiers. These amplifiers might be part of waveform synthesizers, where different spectral parts are parametrically amplified in one or several stages [3,4]. For this application, the quality of the synthesis of the different spectral regions depends in parts on the spatial quality of the beams, determined not only by the amplification stages, but also by the generation step.…”

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Wavefront analysis of a white-light supercontinuum

Kueny¹,

Meier²,

Lévecq³

et al. 2018

Opt. Express

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40-µJ passively CEP-stable seed source for ytterbium-based high-energy optical waveform synthesizers

Cited by 24 publications

References 36 publications

CEP dependence of signal and idler upon pump-seed synchronization in optical parametric amplifiers

CEP dependence of signal and idler upon pump-seed synchronization in optical parametric amplifiers

20-mJ, sub-ps pulses at up to 70 W average power from a cryogenic Yb:YLF regenerative amplifier

Wavefront analysis of a white-light supercontinuum

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