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Mode-Locked Semiconductor Lasers
Published in Joachim Piprek, Handbook of Optoelectronic Device Modeling and Simulation, 2017
Eugene Avrutin, Julien Javaloyes
The model used in Marconi et al. (2014) was a DDE in its classical form of Vladimirov and Turaev (2005), derived for a hypothetical unidirectional ring laser with large gain and absorption per round-trip (and with the linewidth enhancement factors set to zero as the dynamic effects studied did not significantly depend on them), but the theoretical predictions of the paper were realized experimentally (Marconi et al., 2014) using a vertical external cavity surface-emitting laser (VECSEL). A laser of this type consists of an amplifying (gain) chip and a semiconductor saturable absorber mirror (SESAM) chip, separated by an unguided free-space propagation path (with collimating optics to direct the beam and control the ratio of the spots over the two facets). Various harmonic regimes were realized with this laser, with the number of pulses between 0 and 19 successfully coexisting at high enough currents. The authors then went on (Marconi et al., 2015) to realize the multistability in the long laser to generate individually addressable pulses and sequences of pulses, all very well reproduced by the same DDE model.
Laser Sources Based on Gaseous, Liquid, or Solid-State Active Media
Published in Helmut H. Telle, Ángel González Ureña, Laser Spectroscopy and Laser Imaging, 2018
Helmut H. Telle, Ángel González Ureña
Commercial Ti:sapphire laser systems generating ultrashort pulses are mostly exploiting passive mode-locking configurations, incorporating a saturable Bragg reflector (SBR), or a semiconductor saturable absorber mirror (SESAM)—see its conceptual construction in Figure 4.17; or using Kerr lens mode locking (KLM). Pulse durations of the order of 100 fs are common place, and some commercial devices even offer pulse durations down to around 10 fs. The shortest pulses obtained directly form a Ti:sapphire laser were around 5.5 fs, corresponding to less than two light cycle oscillations (see Morgner et al. 1999); see Figure 4.18. Typically, pulse repetition rates are in the range 70–100 MHz, and their average output powers are of the order of 100–1000 mW.
Switchable and dual-wavelength ultrafast fibre lasers with an MoTe2-based saturable absorber
Published in Journal of Modern Optics, 2020
Passively mode-locked fibre lasers have been broadly investigated from experimental laboratory systems to commercial instruments due to their inherent advantages of compact configuration, excellent pulse quality and freedom from misalignment [1–9]. In the past decades, semiconductor saturable absorber mirror, nonlinear optical loop mirror and nonlinear polarization rotation technique have been extensively used to realize passive mode locking [1,2,3,4,6,9]. During recent years, low-dimensional nanomaterials have been explored as effective saturable absorbers (SA) in mode-locked lasers [10–12]. Liu et al. have demonstrated a nanotube-mode-locked all-fibre oscillator emitting triple-wavelength solitons by using fibre Bragg gratings [12]. Among them, transition metal dichalcogenides (TMDs), such as molybdenum disulphide (MoS2) and tungsten disulphide (WS2), are proven to exhibit saturable absorption property [13–16], in which the optical absorbance decreases with the enhancement of the incident laser intensity and becomes saturated above a certain threshold. By comparing to graphene, molybdenum disulphide (MoS2) and tungsten disulphide (WS2) have been extensively studied [5,16]. The applications of WS2 in 1.94 µm mode-locked ultrafast fibre laser have been reported by Jung et al. [17].