Low-loss saturable absorbers based on tapered fibers embedded in carbon nanotube/polymer composites

Amós Martínez, Mohammed Al Araimi, Artemii Dmitriev, Petro Lutsyk, Shen Li, Chengbo Mou, Oleksiy Rozhin, Misha Sumetsky, Sergei K. Turitsyn

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The emergence of low-dimensional materials has opened new opportunities in the fabrication of compact nonlinear photonic devices. Single-walled carbon nanotubes were among the first of those materials to attract the attention of the photonics community owing to their high third order susceptibility, broadband operation, and ultrafast response. Saturable absorption, in particular, has become a widespread application for nanotubes in the mode-locking of a fiber laser where they are used as nonlinear passive amplitude modulators to initiate pulsed operation. Numerous approaches have been proposed for the integration of nanotubes in fiber systems; these can be divided into those that rely on direct interaction (where the nanotubes are sandwiched between fiber connectors) and those that rely on lateral interaction with the evanescence field of the propagating wave. Tapered fibers, in particular, offer excellent flexibility to adjust the nonlinearity of nanotube-based devices but suffer from high losses (typically exceeding 50%) and poor saturable to non-saturable absorption ratios (typically above 1:5). In this paper, we propose a method to fabricate carbon nanotube saturable absorbers with controllable saturation power, low-losses (as low as 15%), and large saturable to non-saturable loss ratios approaching 1:1. This is achieved by optimizing the procedure of embedding tapered fibers in low-refractive index polymers. In addition, this study sheds light in the operation of these devices, highlighting a trade-off between losses and saturation power and providing guidelines for the design of saturable absorbers according to their application.
Original languageEnglish
Article number126103
JournalAPL Photonics
Issue number12
Early online date14 Dec 2017
Publication statusPublished - 14 Dec 2017

Bibliographical note

© 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Funding: H2020 Marie-Sklodowska-Curie Individual Fellowship scheme; Ministry of Higher Education, Sultanate of Oman.


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