We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to ...Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices.
This paper presents a computational framework for modeling hybrid systems in discrete-time. We introduce the class of discrete hybrid automata (DHA) and show its relation with several other existing ...model paradigms: piecewise affine systems, mixed logical dynamical systems, (extended) linear complementarity systems, min-max-plus-scaling systems. We present HYSDEL (hybrid systems description language), a high-level modeling language for DHA, and a set of tools for translating DHA into any of the former hybrid models. Such a multimodeling capability of HYSDEL is particularly appealing for exploiting a large number of available analysis and synthesis techniques, each one developed for a particular class of hybrid models. An automotive example shows the modeling capabilities of HYSDEL and how the different models allow to use several computational tools.
We fabricate a few-layer molybdenum disulfide (MoS₂) polymer composite saturable absorber by liquid-phase exfoliation, and use this to passively Q-switch an ytterbium-doped fiber laser, tunable from ...1030 to 1070 nm. Self-starting Q-switching generates 2.88 μs pulses at 74 kHz repetition rate, with over 100 nJ pulse energy. We propose a mechanism, based on edge states within the bandgap, responsible for the wideband nonlinear optical absorption exhibited by our few-layer MoS₂ sample, despite operating at photon energies lower than the material bandgap.
We demonstrate mode-locking of a thulium-doped fiber laser operating at 1.94 μm, using a graphene-polymer based saturable absorber. The laser outputs 3.6 ps pulses, with ~0.4 nJ energy and an ...amplitude fluctuation ~0.5%, at 6.46 MHz. This is a simple, low-cost, stable and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics.
We exfoliate graphite in both aqueous and non‐aqueous environments through mild sonication followed by centrifugation. The dispersions are enriched with monolayers. We mix them with polymers, ...followed by slow evaporation to produce optical quality composites. Nonlinear optical measurements show ∼5% saturable absorption. The composites are then integrated into fiber laser cavities to generate 630 fs pulses at 1.56 µm. This shows the viability of solution phase processing for graphene based photonic devices.
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