Phosphorene quantum dot saturable absorbers for ultrafast fiber lasers

J. Du,G. Hu,P. Peng,H. Zhang,Z. Guo,J. Chen,M. Zhang,Z. Zheng,X. Zhu

doi:10.1038/srep42357

J. Du, G. Hu + Show 7 more

Open Access

https://doi.org/10.1038/srep42357

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Abstract

We fabricate ultrasmall phosphorene quantum dots (PQDs) with an average size of 2.6 ± 0.9 nm using a liquid exfoliation method involving ultrasound probe sonication followed by bath sonication. By coupling the as-prepared PQDs with microfiber evanescent light field, the PQD-based saturable absorber (SA) device exhibits ultrafast nonlinear saturable absorption property, with an optical modulation depth of 8.1% at the telecommunication band. With the integration of the all-fiber PQD-based SA, a continuous-wave passively mode-locked erbium-doped (Er-doped) laser cavity delivers stable, self-starting pulses with a pulse duration of 0.88 ps and at the cavity repetition rate of 5.47 MHz. Our results contribute to the growing body of work studying the nonlinear optical properties of ultrasmall PQDs that present new opportunities of this two-dimensional (2D) nanomaterial for future ultrafast photonic technologies.

Highlights

We fabricate ultrasmall phosphorene quantum dots (PQDs) with an average size of 2.6 ± 0.9 nm using a liquid exfoliation method involving ultrasound probe sonication followed by bath sonication
The PQDs are prepared by the liquid exfoliation method, an approach previously demonstrated for other 1D and 2D materials[13,14,29,30], and involves ultrasound probe sonication followed by bath sonication of ground powder of bulk according to our previous work[31]
The transmission electron microscopy (TEM) image of the as-synthesized PQDs appears as uniform dots with a diameter of 2.6 ± 0.9 nm [Fig. 1(b)], similar to that reported in the previous literature[16,27]

Summary

Introduction

We fabricate ultrasmall phosphorene quantum dots (PQDs) with an average size of 2.6 ± 0.9 nm using a liquid exfoliation method involving ultrasound probe sonication followed by bath sonication. Amongst the 2D layered material, graphene, consisting of mono- or few-layers of atoms, is one of the most successful examples and has been demonstrated to exhibit remarkable optical and electrical properties, including high optical nonlinear susceptibility, ultrafast carrier dynamics, broadband working wavelength range, in addition to robustness and environmental stability. This has led to the demonstration of numerous nonlinear optical effects of graphene, such as saturable absorption, Kerr nonlinearity and optical parametric processes, suggesting that this material could be a suitable platform for the development of photonic devices. The working wavelength of BP-based ultrafast lasers is expended, covering from 1 μm to 3 μm[18,19,20,21], manifesting its applicability as a new 2D broadband SA material

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