Models for Passively Mode-Locked Fiber Lasers (original) (raw)
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Theory of passively mode-locked lasers for the case of a nonlinear complex-propagation coefficient
Journal of The Optical Society of America B-optical Physics, 1985
We examine passive mode locking, to which not only net-gain saturation but also group-velocity dispersion and self-phase modulation contribute significantly. Different sources of self-phase modulation are considered, and closed-form analytical solutions are obtained. The case of the colliding-pulse mode locking is discussed, and an ideal case is considered, in which the self-phase modulation and group-velocity dispersion are balanced so as to take maximum advantage of this additional shaping mechanism. This mechanism is shown to be similar to that which causes solitons in optical fibers; it provides additional reduction of the pulse width and significantly improves the stability against fluctuations in net gain.
Multistability and hysteresis phenomena in passive mode-locked lasers
Physical Review E, 2000
A passively mode-locked fiber laser is theoretically investigated. The mode locking is achieved using the nonlinear polarization technique. We consider the practical case of the ytterbium-doped fiber laser operating in the normal dispersion regime. The effect of the phase plates is explicitly taken into account. The resulting model reduces to one iterative equation for the optical Kerr nonlinearity, the phase plates and the polarizer, and one partial differential equation for the gain and the dispersion. Numerical simulations allow us to describe several features observed in passively mode-locked fiber lasers such as bistability between the mode lock and the continuous regime, multiple pulse behavior, hysteresis phenomena. The dynamics of the number of pulses as a function of the pumping power is also reported. Pump power hysteresis is demonstrated.
Modeling of Mode-Locked Lasers
… of the 7th WSEAS International Conference …, 2007
Growing demand of communication networks requires ultra-short pulses. Ultra-short pulses can guarantee high data transfer and power. Fiber lasers, which are actively or passively mode-locked to generate ultrashort pulses, are termed as Mode locked fiber lasers. There are a number of methods available for mode-locking of lasers. We have discussed most of them in this paper. At the end a model of actively mode-locked fiber ring laser is simulated. Index terms: Active mode locking, Passive mode locking, Fiber lasers, Non-linear Schrodinger equation (NLSE), Saturable Absorber (SA).
Nonlinear pulse shaping and polarization dynamics in mode-locked fibre lasers
2013
We review our recent progress on the study of new nonlinear mechanisms of pulse shaping in passively modelocked fibre lasers. These include a mode-locking regime featuring pulses with a triangular distribution of the intensity, and spectral compression arising from nonlinear pulse propagation. We also report on our recent experimental studies unveiling new families of vector solitons with precessing states of polarization for multipulsing and bound-state soliton operations in a carbon nanotube mode-locked fibre laser with anomalous dispersion cavity.
Chinese Optics Letters, 2017
An elliptical initial polarization state is essential for generating mode-locked pulses using the nonlinear polarization rotation technique. In this work, the relationship between the ellipticity ranges capable of maintaining mode-locked operation against different pump power levels is investigated. An increasing pump power, in conjunction with minor adjustments to the polarization controller's quarter waveplate, results in a wider ellipticity range that can accommodate mode-locked operation. Other parameters such as noise, pulsewidth, and average output power are also observed to vary as the ellipticity changes.
Physical Review E, 2006
By numerically solving the coupled laser Ginzburg-Landau equations and using the pulse tracing technique to incorporate the cavity effect in the simulation, we have explicitly calculated the soliton polarization ellipses throughout the cavity of a fiber-ring laser mode-locked by the nonlinear polarization rotation technique, and investigated the soliton polarization dynamics in laser cavities. It was found that in a conventional stable soliton operation state, although the soliton polarization varies as the pulse propagates, at a fixed position inside the laser cavity the soliton polarization is invariant with time. However, in the presence of laser dynamics, at a fixed location within the cavity the soliton could either have multiple alternating fixed polarization states or no fixed polarization state at all, depending on the soliton dynamics.
Journal of Optics A: Pure and Applied Optics, 2004
We investigate theoretically a fiber laser passively mode-locked with nonlinear polarization rotation. A unidirectional ring cavity is considered with a polarizer placed between two sets of a halfwave plate and a quarterwave plate. A master equation is derived and the stability of the continuous and mode-locked solutions is studied. In particular, the effect of the orientation of the four phase plates and of the polarizer on the mode-locking regime is investigated.
Nonlinear pulse shaping and polarization dynamics in mode-locked fiber lasers
2014
We review our recent progress on the study of new nonlinear mechanisms of pulse shaping in passively mode-locked fiber lasers. These include a mode-locking regime featuring pulses with a triangular distribution of the intensity, and spectral compression arising from nonlinear pulse propagation. We also report on our recent experimental studies unveiling new types of vector solitons with processing states of polarization for multipulse and tightly bound-state soliton (soliton molecule) operations in a carbon nanotube (CNT) mode-locked fiber laser with anomalous dispersion cavity.
Analysis of soliton pattern formation in passively mode-locked fiber lasers
Physical Review A, 2008
We give a detailed theoretical analysis of spontaneous periodic pattern formation in fiber lasers. The pattern consists of a bound state of hundreds of pulses in a ring fiber laser passively mode locked by nonlinear rotation of the polarization. The phenomenon is described theoretically using a multiscale approach to the gain dynamics: the fast evolution of a small excess of gain is responsible for the stabilization of a periodic pattern, while the slow evolution of the mean value of gain explains the finite length of the quasiperiodic soliton train. The resulting model is well adapted to experimental observations in a Er:Yb-doped double-clad fiber laser.