Linear chirp instability analysis for ultrafast pulse metrology

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

doi:10.1364/josab.37.000074

Cited by 9 publications

(12 citation statements)

References 32 publications

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“…However, there are some cases in which the conventional FROG algorithms do not converge due to instabilities in the pulse train [16]. In the last decade it has been proposed an approach to a type of unstable FROG traces, called CA FROG traces, that presents double temporal structure, based on the division of the original pulse train in two auxiliary pulses called coherent artifact and average [16][17][18].…”

Section: Modified Frog Reconstruction Algorithmmentioning

confidence: 99%

“…In previous works [16][17][18] the CA represents the shortest repeating substructure of the pulse train, so it is imposed that the CA is a Fourier Transform Limit (FTL) pulse. In this work we propose another interpretation of the CA as the average of the fs scale variations reported in the noise-like pulses regime, letting the reconstruction algorithm to retrieve the phase of the CA without imposing any constrains.…”

Section: Modified Frog Reconstruction Algorithmmentioning

confidence: 99%

“…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%

See 3 more Smart Citations

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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Section: Modified Frog Reconstruction Algorithmmentioning

confidence: 99%

Section: Modified Frog Reconstruction Algorithmmentioning

confidence: 99%

“…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%

See 2 more Smart Citations

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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“…A prominent variation of the pulse electric field on a short time scale leads to the appearance of a narrow feature in the recorded nonlinear signal, which is called a "coherent artifact". This artifact can confuse interpretation of the autocorrelation or SPIDER measurements, including of the pulse length and temporal structure 12,13 . On the contrary, the spatial and temporal chirp variations manifest themselves in the standard FROG setup as a discrepancy between the measured and the retrieved FROG traces 6,11 .…”

Section: Introductionmentioning

confidence: 99%

Dispersion Scan Frequency Resolved Optical Gating For Evaluation of Pulse Chirp Instability

Guesmi¹,

Veselá²,

Žídek³

2020

Preprint

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The commonly used methods to characterize ultrafast laser pulses, such as frequency-resolved optical gating (FROG) and dispersion scan (d-scan), face problems when they are used on pulses varying within the acquisition time or laser beam. Such chirp variation can be identified by a discrepancy between the measured FROG and d-scan traces and their reconstructed counterparts. Nevertheless, quantification of the instability from the experimental data is a more complex task. In this work, we evaluate the precision of chirp instability quantification based on three different pulse characterization techniques. Two commonly used techniques FROG and d-scan are compared to a new method dispersion scan FROG (D-FROG) that combines the idea of dispersion scanning with the FROG method. We demonstrate the characterization of pulses generated from NOPA together with pulses processed by a 4f-pulse shaper without and with SLM-adjusted phase. In this paper, we validate the performance of the new method to estimate the chirp instability and, therefore, to improve the reconstruction of the measured results. Furthermore, we discuss the instability origin of each measurement case by using fast-scan autocorrelation traces.

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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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Linear chirp instability analysis for ultrafast pulse metrology

Cited by 9 publications

References 32 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

Dispersion Scan Frequency Resolved Optical Gating For Evaluation of Pulse Chirp Instability

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

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