Comparative study on the temporal contrast of femtosecond mode-locked laser oscillators

Stuart, Nicholas; Robinson, T.; Hopps, Nick; Parry, B.; Musgrave, Ian; Nersisyan, G.; Sharba, Ahmed; Zepf, Matthew; Smith, R. A.

doi:10.1364/ol.41.003221

Cited by 20 publications

(13 citation statements)

References 21 publications

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“…and Alessi et al. [290, 292] , revealing unexpected features close to the mode-locked pulses. These features can only be removed using temporally gated amplification (ps-OPA) or nonlinear processes.…”

Section: Future Technologiesmentioning

confidence: 83%

“…Oscillators: The innate contrast of a range of modelocked oscillators which form the seed for all petawatt lasers has been characterized by Stuart et al and Alessi et al [290,292] , revealing unexpected features close to the mode-locked pulses. These features can only be removed using temporally gated amplification (ps-OPA) or nonlinear processes.…”

Section: Improvements In Temporal Contrastmentioning

confidence: 99%

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Petawatt and exawatt class lasers worldwide

Danson

Haefner

Bromage

et al. 2019

High Pow Laser Sci Eng

743

406

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In the 2015 review paper ‘Petawatt Class Lasers Worldwide’ a comprehensive overview of the current status of high-power facilities of ${>}200~\text{TW}$ was presented. This was largely based on facility specifications, with some description of their uses, for instance in fundamental ultra-high-intensity interactions, secondary source generation, and inertial confinement fusion (ICF). With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification (CPA), which made these lasers possible, we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed. We are now in the era of multi-petawatt facilities coming online, with 100 PW lasers being proposed and even under construction. In addition to this there is a pull towards development of industrial and multi-disciplinary applications, which demands much higher repetition rates, delivering high-average powers with higher efficiencies and the use of alternative wavelengths: mid-IR facilities. So apart from a comprehensive update of the current global status, we want to look at what technologies are to be deployed to get to these new regimes, and some of the critical issues facing their development.

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Section: Future Technologiesmentioning

confidence: 83%

Section: Improvements In Temporal Contrastmentioning

confidence: 99%

Petawatt and exawatt class lasers worldwide

Danson

Haefner

Bromage

et al. 2019

High Pow Laser Sci Eng

743

406

View full text Add to dashboard Cite

show abstract

“…In the worst case (∆/β = 1.5), an enhancement over I FL of more than one order of magnitude is realized. For ∆/β = 0.5, the extinction ratio drops between 10 −6 (half-period after the pulse) and 3 × 10 −3 (first satellite peak), values that are comparable to those of fiber mode-locked lasers [14]. As many studies have already proven it [15][16][17][18], it is possible to multiply the repetition rate of a periodic optical signal with an integer factor by carrying out phase-only line-by-line shaping.…”

mentioning

confidence: 57%

Electro-optically modulated lasers: pulse energy and contrast enhancement derived from a theoretical spectrum

Marion

Lhermite²

2020

Opt. Lett.

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In this Letter, we derive analytically the complex optical spectrum of a pulsed laser source obtained when a frequency comb generated by phase modulation is input into a synchronized intensity modulator. We then show how this derivation of the spectrum may help to achieve unprecedented, to the best of our knowledge, accuracy during the experimental spectrum correction step usually carried out with an optical spectrum processor. In numerical examples, for a given average power, we present up to a 75% increase in peak power and an enhancement of the extinction ratio by at least 3 orders of magnitude. This method also enables large-factor rate-multiplications of these versatile coherent sources using the Talbot effect with negligible signal degradation.

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“…This experimentally demonstrates that the contrast of the idler pulse will not be degraded by the scattered photons from the signal. Second, a high dynamic range third-order auto-correlator developed by the authors [19] has been used to measure the contrast of the seed and the idler pulses in the pico-second scale with 210 fs resolution. Given that the ASE level of the input pulse exceeds the 10 −5 level in the pico-second scale, figure (5) shows that the cleaning system reduces that level below the detection-threshold of the third order auto-correlator (≈ 7×10 −10 ).…”

Section: Fig 3 Amentioning

confidence: 99%

“…( 5 and 6), can be due to two reasons. First, although the pulse of our oscillator has a high contrast ratio, as reported in [19], the low available energy from the oscillator at the time of implementing the contrast measurement forced us to increase the number of passes into the regenerative amplifier, seeking more gain. This could lead to an increase of the ASE level in the output pulse.…”

Section: Fig 3 Amentioning

confidence: 99%

Generation of high contrast and high spatial quality idler from a low-gain optical parametric amplifier

et al. 2016

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The temporal contrast of a regeneratively amplified, sub-picosecond pulse is enhanced employing a lowgain optical parametric amplification stage self-pumped by the second-harmonic of the pulse. Through careful characterization of the two related non-linear processes and optimization of the non-collinear geometry, a robust high-contrast idler pulse has been generated, with excellent spatial quality in both the near and far field. The overall energy conversion efficiency exceeds 14%, with 33% intensity conversion efficiency. The temporal cleaning is implemented without any bandwidth losses or spectral shift and produces approximately 20% temporal shortening. These experimental findings are in excellent agreement with numerical calculations. Exciting and rapidly developing investigations of lasermatter interactions at relativistic laser intensities have been enabled by the development of chirped-pulse amplification (CPA) techniques [1]. For these kind of interactions the temporal contrast of the laser pulse is one of the key parameters, since prepulses and pedestals can damage or deform the target before the arrival of the main pulse [2,3]. A suitably high contrast for some applications cannot be achieved from a regenerative pre-amplifier because even a very small pre-pulse can be amplified to a level sufficient to pre-ionize the target. In addition, the amplified spontaneous emission (ASE) from regenerative amplifiers can form a long pedestal around the main pulse, contributing to the degradation of the temporal contrast. Therefore, the development of laser technologies enabling ever growing intensities has been accompanied by the development of many techniques [4][5][6][7][8][9][10][11][12] for enhancing the temporal contrast.Short pulse, low gain optical parametric amplification (OPA) is one of the most efficient contrast enhancement techniques that can work at the front end of a high power laser system. Pumping an OPA with a sufficiently short pump pulse, typically shorter than 1 ps, ensures that the pump overlaps only with the main signal pulse, leaving discrete pre-pulses and the majority of the ASE pedestal outside the amplification window. This leads to enhancement of the temporal contrast of the signal by a factor equivalent to the gain factor [12]. Generating the pump pulse of the OPA by frequency doubling a part of the input pulse and using the idler rather than the signal can provide an extreme contrast enhancement that can reach up to the third power of the input contrast [9]. This theoretical prediction is limited only by parametric noise and scattered photons from the signal overlapping with the idler.In its simplest configuration, as previously described by R. Shah, et al. [10], the contrast enhancement system consists of a second harmonic generation (SHG) and a non-collinear OPA stage. The input pulse is split into two parts and the doubling stage converts a large part of the pulse energy into a second harmonic (SH) pulse to pump the following OPA stage, which is seeded by the rest of the input pul...

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Comparative study on the temporal contrast of femtosecond mode-locked laser oscillators

Cited by 20 publications

References 21 publications

Petawatt and exawatt class lasers worldwide

Petawatt and exawatt class lasers worldwide

Electro-optically modulated lasers: pulse energy and contrast enhancement derived from a theoretical spectrum

Generation of high contrast and high spatial quality idler from a low-gain optical parametric amplifier

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