Retrieving the coherent artifact in frequency-resolved optical gating

Escoto, Esmerando; Jafari, Rana; Trebino, Rick; Steinmeyer, Günter

doi:10.1364/ol.44.003142

Cited by 13 publications

(15 citation statements)

References 21 publications

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“…Since the last decade, it has been studied the effect of different types of instabilities using conventional characterization techniques [16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, recently it has been published an experimental study of instabilities in photonic-crystal fibre of a fibre laser using D-scan [19]. Regarding the FROG technique, previous works [16][17][18] focused on the study of FROG traces resulting from an unstable train of pulses (hereafter called CA FROG traces), so that the resulting trace can be modelled as the contribution of two auxiliary components. On one hand we have the coherent artifact (CA), and on the other hand we have the average pulse.…”

Section: Introductionmentioning

confidence: 99%

“…This can be understood as a way to model the unstable pulse train and a chance to extract additional information from the FROG traces. Recently, Escoto et al [17] have proposed a modified Generalized Projections Algorithm in order to model this kind of FROG traces, from a numerical approach. Following this idea, we have developed a modified Principal Components Generalized Projections Algorithm (PCGPA) to study CA FROG traces and we have applied it to experimentally study an unstable passive mode-locked EDFL with an amplification stage outside the cavity.…”

Section: Introductionmentioning

confidence: 99%

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Coherent artifact and time-dependent polarization in amplified ultrafast erbium-doped fibre lasers

López-Ripa

Alonso

Jarabo

et al. 2021

Optics & Laser Technology

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Mode-locked erbium-doped fibre lasers are ultrashort pulsed sources widely studied due to their versatility and multiple applications in the near infrared range. Here we present the experimental study of the emission of a passive mode-locked erbium-doped fibre laser with an amplification stage outside the cavity by means of Frequency Resolved Optical Gating (FROG) and spectral interferometry. Due to shot-to-shot instabilities, the FROG traces can be understood as the combination of two different traces, corresponding to the coherent artifact and the average pulse characteristics. We have modified a Principal Components Generalized Projections Algorithm, in order to make it able to retrieve efficiently both the coherent artifact and the average pulse. In addition, we study the temporal dependence of the polarization, showing that the pulses present time-dependent polarization with a stable spectral relative phase between the horizontal and vertical projections. Up to our knowledge, this is the first experimental study that shows the FROG measurements of unstable pulse trains associated with the coherent artifact and analyses the time-dependent polarization in ultrafast fibre lasers.

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“…Since the last decade, it has been studied the effect of different types of instabilities using conventional characterization techniques [16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coherent artifact and time-dependent polarization in amplified ultrafast erbium-doped fibre lasers

López-Ripa

Alonso

Jarabo

et al. 2021

Optics & Laser Technology

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“…Regarding the characterization of stable ultrashort pulses, different techniques have been developed 28 . Over the last few years, the problem of the temporal measurement of unstable pulse trains has relied on using temporal characterization techniques such as autocorrelation, SPIDER (spectral phase interferometry for electric field reconstruction) or FROG (frequency-resolved optical gating) 29,30 . In autocorrelation, the pulse train instability is reflected in a narrow spike at the centre of the signal, which can mislead to a wrong pulse duration measurement.…”

mentioning

confidence: 99%

“…In interferometric measurements, such as SPIDER, previous works reported that the instability results in a reduction of contrast that cannot be experimentally identified 29 . In the case of FROG, the 2D trace is sensitive to the pulse train instability, which is associated to a higher error in the convergence 29 , very recently having been shown a specific analysis to identify the average pulse and coherent artifact contributions 30 . The effect of spectral amplitude and phase instabilities has been studied theoretically using the MIIPS (multiphoton intrapulse interference phase scan) technique and experimentally applied to a titanium-sapphire oscillator and amplifier 31,32 .…”

mentioning

confidence: 99%

Detection and elimination of pulse train instabilities in broadband fibre lasers using dispersion scan

Alonso

Torres-Peiró²,

Romero³

et al. 2020

Sci Rep

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We use self-calibrating dispersion scan to experimentally detect and quantify the presence of pulse train instabilities in ultrashort laser pulse trains. We numerically test our approach against two different types of pulse instability, namely second-order phase fluctuations and random phase instability, where the introduction of an adequate metric enables univocally quantifying the amount of instability. The approach is experimentally demonstrated with a supercontinuum fibre laser, where we observe and identify pulse train instabilities due to nonlinear propagation effects under anomalous dispersion conditions in the photonic crystal fibre used for spectral broadening. By replacing the latter with an allnormal dispersion fibre, we effectively correct the pulse train instability and increase the bandwidth of the generated coherent spectrum. This is further confirmed by temporal compression and measurement of the output pulses down to 15 fs using dispersion scan.

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Reliable determination of pulse-shape instability in trains of ultrashort laser pulses using frequency-resolved optical gating

Jafari

Khosravi

Trebino

2022

Sci Rep

Self Cite

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We describe a reliable approach for determining the presence of pulse-shape instability in a train of ultrashort laser pulses. While frequency-resolved optical gating (FROG) has been shown to successfully perform this task by displaying a discrepancy between the measured and retrieved traces for unstable trains, it fails if its pulse-retrieval algorithm stagnates because algorithm stagnation and pulse-shape instability can be indistinguishable. So, a non-stagnating algorithm—even in the presence of instability—is required. The recently introduced Retrieved-Amplitude N-grid Algorithmic (RANA) approach has achieved extremely reliable (100%) pulse-retrieval in FROG for trains of stable pulse shapes, even in the presence of noise, and so is a promising candidate for an algorithm that can definitively distinguish stable and unstable pulse-shape trains. But it has not yet been considered for trains of pulses with pulse-shape instability. So, here, we investigate its performance for unstable trains of pulses with random pulse shapes. We consider trains of complex pulses measured by second-harmonic-generation FROG using the RANA approach and compare its performance to the well-known generalized-projections (GP) algorithm without the RANA enhancements. We show that the standard GP algorithm frequently fails to converge for such unstable pulse trains, yielding highly variable trace discrepancies. As a result, it is an unreliable indicator of instability. Using the RANA approach, on the other hand, we find zero stagnations, even for highly unstable pulse trains, and we conclude that FROG, coupled with the RANA approach, provides a highly reliable indicator of pulse-shape instability. It also provides a typical pulse length, spectral width, and time-bandwidth product, even in cases of instability.

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Retrieving the coherent artifact in frequency-resolved optical gating

Cited by 13 publications

References 21 publications

Coherent artifact and time-dependent polarization in amplified ultrafast erbium-doped fibre lasers

Coherent artifact and time-dependent polarization in amplified ultrafast erbium-doped fibre lasers

Detection and elimination of pulse train instabilities in broadband fibre lasers using dispersion scan

Reliable determination of pulse-shape instability in trains of ultrashort laser pulses using frequency-resolved optical gating

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