Modeling of Mode-Locked Lasers (original) (raw)
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Ultrashort pulse formation and evolution in mode-locked fiber lasers
Applied Physics B, 2011
Passive mode-locking in fiber lasers is investigated by numerical and experimental means. A nondistributed scalar model solving the nonlinear Schrödinger equation is implemented to study the starting behavior and intra-cavity dynamics numerically. Several operation regimes at positive net-cavity dispersion are experimentally accessed and studied in different environmentally stable, linear laser configurations. In particular, pulse formation and evolution in the chirped-pulse regime at highly positive cavity dispersion is discussed. Based on the experimental results a route to highly energetic pulse solutions is shown in numerical simulations. 1 Introduction Lasers have been the subject of extensive research and development over the last 50 years, driven by their huge application potential. However, laser oscillators may be likewise
Models for Passively Mode-Locked Fiber Lasers
Fiber and Integrated Optics, 2008
We give a review of theoretical approaches we have recently developed for the description of passively modelocked fiber lasers. Mode-locking is assumed to be obtained with nonlinear polarization rotation. The first approach takes the form of a cubic Ginzburg-Landau equation where the coefficients take into account the orientation of the phase plates. A fully analytical study can be performed. The second model includes gain saturation allowing to investigate multiple pulse behaviour and multistability phenomena. Under some approximations this model reduces to a complex quintic Ginzburg-Landau equation. Passive harmonic modelocking can also be obtained with a suitable adaptation of the model.
An Experimentally Validated Discrete Model for Dispersion-Tuned Actively Mode-Locked Lasers
IEEE Journal of Selected Topics in Quantum Electronics, 2000
In this paper, we present a new discrete model describing the steady-state characteristics of dispersion-tuned actively mode-locked fiber lasers pulses after each component in the cavity. The model was developed to perfect the design and further the knowledge of the capabilities of such lasers. The discrete model is compared to the traditional average model that is shown to be a limit case of the former. Several laser cavities were then built, with laser parameters changing over 4 order of magnitudes, in order to validate both models with experimental data. Both models show excellent agreement with the experimental data. Design considerations and limitations are then discussed in the light of this new model.
New Trends in Optical Network Design and Modeling, 2001
A theoretical study of a high repetition rate laser source based on a novel modelocking technique is presented. This technique relies on the fast saturation and recovery of a semiconductor optical amplifier induced by an external optical pulse and has been used to obtain 4.3 ps pulses at 20 GHz. A numerical model of the fiber ring laser has been developed describing the mode-locking process in the laser oscillator and providing solutions for the steady-state mode-locked pulse profile. The critical parameters of the system are defined and analyzed and their impact on the formation of the mode-locked pulses is examined. The comparison between the theoretical results and the experimental data reveals very good agreement and has allowed the optimization of the performance of the system in terms of these parameters.
New time-domain model for active mode locking, based on the transmission line laser model
IEE Proceedings J Optoelectronics
A new time-domain model for active mode-locking in semiconductor lasers, coupled to external cavities including a filter, is developed. Unlike previous time domain models, the propagating field is considered, rather than the photon density. This allows timedomain filters to be used to model the spectral dependencies of gain, spontaneous emission and dispersive components. Also, Fourier transforms of the field reveal the output spectrum. The new model is compared with results from a previous timedomain model before the effects of bandwidth limiting on pulse shape are investigated. Results show that transform limited pulses can be generated. However, their stability is critically dependent on the drive conditions and the spontaneous emission coupled to the lasing mode. Paper 6876J (E13), first received 31st March and in revised form 21st
Theoretical Study on Passively Mode-Locked Fiber Lasers with Saturable Absorber
Fiber and Integrated Optics, 2018
In this paper, passively mode-locked erbium-doped fiber lasers based on saturable absorber (SA) have been theoretically studied. The energetics and pulse properties for different fiber laser cavity configurations have been investigated and the effects of each component (active fiber, passive fiber, and SA) in the laser cavity have been studied. This numerical study takes into account the temporal change in the saturable absorption (dq/dt).The presented simulations could be highly useful for understanding, optimizing, and improving passively mode-locked fiber lasers with SA.
Mode-locking pulse dynamics in a fiber laser with a saturable Bragg reflector
Journal of the Optical Society of America B, 1997
A theoretical model is developed for the pulse dynamics in a ber laser modelocked by a saturable Bragg re ector (SBR) and operating in regimes beyond the scope of the master modelocking equation. An asymptotically valid modelocked evolution equation is derived which includes a heuristic model for the SBR dynamics. The model employed allows, for the rst time to our knowledge, to directly compare (with no free parameters) theoretical predictions of the pulse spectral and temporal pro les with experimental results in both the normal and anomalous dispersion regimes. Extensive numerical simulations of the governing evolution equation, an averaged equation, and analytical solutions are found to be in excellent agreement with experimental results.
Physical Review A, 2012
On the basis of numerical simulation, it is found that powerful long-distance soliton wings can be formed by dispersive waves which are emitted by solitons because of lumped elements in a laser cavity. We analyze peculiarities of the interaction of two solitons through such wings in lasers with lumped saturable absorbers. Various sets of bound steady states of a two-soliton molecule are demonstrated. The relation between the spectral sidebands and the dispersive-wave wings of a soliton is found. The periodic changes in a soliton's profile during its pass through the laser cavity are studied.
Analysis Frequency Modulation Mode-Locked Fiber Laser by Using ABCD Rule
2010
In this paper the study of Frequency Modulation (FM) mode-locking fiber laser is presented. The time-domain ABCD law was employed to clarify the impacts of optical elements on the mode-lock pulses. ABCD matrices formalism in the time domain has been developed under a Gaussian paraxial approximation. Also, these matrices apply to the theory of the actively mode-locked fiber laser. The numerical results are obtained by using MATLAB software. The analysis was produced a shorter than 3.16ps duration pulses in laser mode locked with FM modulator driven at repetition frequency of 10GHz and cavity has anomalous dispersion of 0.015ps/m and nonlinearity of 0.02Wm. The values of chirp are plotted versus average power with many values of dispersion. All relationship between the pulse laser parameters and other effective parameters like, second order dispersion, nonlinearity, average input power, repetition frequency and optical filter bandwidth are plotted and discussed. Keyword: FM mode locki...