Experimental study of non-stationary operation of a dual-wavelength passively mode-locked fibre ring laser

Abstract

In this paper, we report an experimental study of different dynamics taking place in a 20 m long passively mode-locked fibre ring laser in dual-wavelength operation, at 1531 nm and 1558 nm. For different polarization adjustments, self-starting mode locking is obtained, yielding different types of emission: bunches of solitons in quasi-stationary regime, a compact bunch of solitons coexisting with loose bunches of solitons, a noise-like pulse coexisting with bunches of solitons and a noise-like pulse displaying quasi-periodic fluctuations. In each regime, we extract information on the pulse dynamics from measurements of the temporal profile evolution using a 16 GHz real-time oscilloscope and, at the same time, we propose a phase-space diagram representation of the intensity versus the energy of the temporal profile of the pulses; the latter allows evidencing patterns that could not be identified using conventional measurement techniques.

Numerical approaches for solving the nonlinear Schrödinger equation in the nonlinear fiber optics formalism

“…In this pulse propagation study, the conservation of energy is a good reference to select the appropriate method, because it represents a fundamental parameter in the study of pulse dynamics that is obtained by the shape information of the intensity pulse profile. For a dissipative system, this parameter is not conserved, as shown in [44] by the pulse energy evolution in different dissipative pulse dynamics generated by a mode-locked fiber ring laser. In a similar way, H and M would not be conserved in a dissipative system.…”

Complex dynamics of passively mode-locked fiber lasers with strict polarization control

“…Finally, another kind of complex dynamics, involving quasi-periodic energy fluctuations, wavelength shifts, extreme-intensity events, the formation of solitons in a NLP, and even NLP to solitons conversion, was observed experimentally and described in a ring laser cavity (Fig. 1a)) [57,58]. In this case, measurements were performed using a 16 GHz fast oscilloscope.…”

Numerical study of supercontinuum generation using noise-like pulses in standard fibre

“…First described by Horowitz et al [23], this regime presents a smooth and wide average optical spectrum with an absence of Kelly sidebands, and a double-scale autocorrelation trace consisting of a central coherence spur over a wide pedestal, as typical signatures [24,25]. In addition to the fundamental mode-locking operation, NLPs are associated with some puzzling phenomena such as high-order harmonic mode-locking regimes [26,27], the splitting of the main bunch into multiple packets [28][29][30], the hybrid NLP-solitons regime [31][32][33] and the manifestation of optical rogue waves [34][35][36][37]. In the frame of SCG, NLPs have proven to be an excellent seed for obtaining very broad spectra because they present some advantages; for instance, NLPs allow about 1000 times more energy per pulse than a soliton (~100 s of nJ) [12,18,38]; besides, because these long waveforms are robust against dispersion, nonlinear effects are significant over long lengths of fibre, which results in enhanced spectral broadening.…”