General formula for calculation of amplified spontaneous emission intensity

Moghadam, G. Ghani; Farahbod, Amir Hossein

doi:10.1007/s11082-016-0505-2

Cited by 9 publications

(5 citation statements)

References 20 publications

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“…The signal light has few times to be amplified repeatedly, and the power is weak. In this situation, the ASE process needs to be considered to correctly analyze the power output of the signal light [16][17][18][19] . This is also why the conventional fiber laser power model is no longer applicable.…”

Section: Power Output Correction Model Of the Wgmrfiltered Fiber Lasermentioning

confidence: 99%

Power output correction model of narrow linewidth ring fiber laser filtered with whispering gallery mode resonator

Wang,

Xu,

Cui

et al. 2024

中国光学快报

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A whispering gallery mode resonator (WGMR) filter can narrow laser linewidth while significantly changing the output power characteristics of fiber laser system. It is found that traditional laser output power model is invalid. We report a correction model of a narrow linewidth fiber laser filtered with a WGMR to analyze its power. We believe that the loss of the laser system and the threshold gain increase caused by the WGMR filter lead to the predominate amplified spontaneous emission during the original laser period. According to that, we assume the correction coefficient is an exponential decay related to the Er-doped fiber length in the large loss situation, and we verify it experimentally. As a result, the correction model is valid for WGMR-filtered fiber laser.

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Section: Power Output Correction Model Of the Wgmrfiltered Fiber Lasermentioning

confidence: 99%

Power output correction model of narrow linewidth ring fiber laser filtered with whispering gallery mode resonator

Wang,

Xu,

Cui

et al. 2024

中国光学快报

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“…These correspond to gain-length products of 8.7, 6.1, and 8.1 in the KrF, XeCl and XeF case. If it is compared to the usual gain-length product of ASE-depleted excimer gain modules, whose value is typically around 11 for all cases, as seen in Figure 1 of [52], different K values are obtained for the KrF, XeCl and XeF with K KrF = 0.76, K XeCl = 0.53, and K XeF = 0.74.…”

Section: Contrast Issues For Short-pulse Amplification In Excimersmentioning

confidence: 99%

“…For the calculation of the maximum value of short-pulse amplification, we have to refer to Equation (18) as c * power = 0.3 and c * pre = 0.5. Assuming a KrF amplifier, which typically allows the development of ASE in a solid angle Ω = 10 4 as seen in Figure 1 of [52], one can set a limit of g 0 L ≈ 4, where ASE remains in the low intensity, slowly rising region. This, however, also limits the effective gain length product (for saturated short-pulse amplification) to g power L ~1.2, allowing a power amplification of somewhat more than G power ~3 for short pulses.…”

Section: Practical Consequences Of the Gain Dynamics For Short-pulse ...mentioning

confidence: 99%

Generation of Intense and Temporally Clean Pulses—Contrast Issues of High-Brightness Excimer Systems

et al. 2022

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In high-brightness excimer systems, the direct amplification of short pulses allows temporal filters to be integral parts of the ultraviolet (UV) amplifier chain, where the only origin of the noise is the amplified spontaneous emission (ASE), generated by the amplifier(s) following the filter. The ASE, however, develops faster than the short main pulse; in this paper, the dynamic short- and long-pulse amplification properties of KrF, XeCl and XeF excimers are studied, with special emphasis on the temporal contrast. It was found that, beyond the saturation of amplification, the relaxation of the B state in KrF, together with the contribution of the absorption of the transiently populated X state in XeCl and XeF, are the main limitations for both the extraction efficiency and the contrast. For all excimers, the stimulated transition rates and the dependence of the achievable contrast on the level of saturation were derived. Local quantities were introduced to characterize the deterioration of the contrast for a unit gain length of KrF amplifiers. A KrF power amplifier of limited gain (G ≈ 3), following the newly introduced nonlinear Fourier filter, is capable of reaching contrast levels beyond the previously reported 1011–1012.

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“…Recently, Ghani‐Moghadam and Farahbod have solved these equations numerically, and the results of numerical computations for ASE normalized intensity by integrating

I / {normalI}_{s} = \int_{- \infty}^{normal∞} italicd ν I^{+} false(L, ν false) / I_{s}

relative to

σ_{p} NL = {normalg}_{\circ} L

were obtained. [ 16 ] Thus, by solving this equation numerically and comparing it with Svelto's results, a general formula is obtained that calculates the intensity of ASE in all low, moderate and high intensity regions and for both homogeneous and inhomogeneous broadening. Therefore, the limitation of Linford formula has been vanished.…”

Section: Investigation Of Gain Saturation Region With General Formulamentioning

confidence: 99%

“…Therefore, the limitation of Linford formula has been vanished. The general formula is presented as follows [ 16 ] :

I false(normalz false) / I_{s} = \frac{ϕ}{2} \ln (1 + γ \frac{normalΩ}{4 π} G {(z)}^{δ})

where G is

\exp false({normalg}_{\circ} l false)

; δ and γ are certain coefficients (Table 1), which are achieved by fitting Equation (8) plot with the resulting graph of the numerical solution.…”

Section: Investigation Of Gain Saturation Region With General Formulamentioning

confidence: 99%

Parametric study of plasma active medium and gain saturation region in a Ne‐like soft X‐ray laser

Ghani-Moghadam¹,

Rezaei

Jafari

et al. 2021

Contributions to Plasma Physics

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Plasmas created by the interaction of high power optical laser with a target surface can be used as a source of soft X‐ray lasers. Plasma and pump laser characteristics play significant role in achieving high gain coefficient for such plasma based on soft X‐ray lasers. In the present work, the plasma active medium parameters for germanium element at a wavelength of 19.6 nm irradiated by a double‐pulse pump laser have been studied using MED103 hydrodynamic code. For this purpose, first, the effects of laser intensity, pulse width and delay time of two pulses on the gain coefficient have been investigated and the optimum conditions for the maximum gain extent of Ne‐like germanium soft X‐ray laser are obtained. Then, in order to calculate the intensity of such high gain lasers in which Linford equation is invalid, we have adopted the general formula of amplified spontaneous emission intensity, which is valid in all range of intensities even at much higher intensities than saturation intensity. Finally, the soft X‐ray laser intensities in the saturated areas for different plasma lengths have been calculated. The results show that the output of soft X‐ray laser intensity with 294 cm−1 gain coefficient can reach to about several times saturated intensity by applying a 1–2 mm plasma length as the active medium.

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General formula for calculation of amplified spontaneous emission intensity

Cited by 9 publications

References 20 publications

Power output correction model of narrow linewidth ring fiber laser filtered with whispering gallery mode resonator

Power output correction model of narrow linewidth ring fiber laser filtered with whispering gallery mode resonator

Generation of Intense and Temporally Clean Pulses—Contrast Issues of High-Brightness Excimer Systems

Parametric study of plasma active medium and gain saturation region in a Ne‐like soft X‐ray laser

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