Ultrafast saturable absorption in TiS2 induced by non-equilibrium electrons and the generation of a femtosecond mode-locked laser

Non-equilibrium electrons induced by ultrafast laser excitation in a correlated electron material can disturb the Fermi energy as well as optical nonlinearity. Here, non-equilibrium electrons translate a semiconductor TiS2 material into a plasma to generate broad band nonlinear optical saturable abs...

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Bibliographic Details
Published in:Nanoscale 2018-05, Vol.10 (20), p.9608-9615
Main Authors: Tian, Xiangling, Rongfei Wei, Liu, Meng, Zhu, Chunhui, Luo, Zhichao, Wang, Fengqiu, Qiu, Jianrong
Format: Article
Language:English
Subjects:
Absorption
Electrons
Equilibrium
Femtosecond pulses
Modulation
Nonlinearity
Pulse duration
Recovery time
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Summary:Non-equilibrium electrons induced by ultrafast laser excitation in a correlated electron material can disturb the Fermi energy as well as optical nonlinearity. Here, non-equilibrium electrons translate a semiconductor TiS2 material into a plasma to generate broad band nonlinear optical saturable absorption with a sub-picosecond recovery time of ∼768 fs (corresponding to modulation frequencies over 1.3 THz) and a modulation response up to ∼145%. Based on this optical nonlinear modulator, a stable femtosecond mode-locked pulse with a pulse duration of ∼402 fs and a pulse train with a period of ∼175.5 ns is observed in the all-optical system. The findings indicate that non-equilibrium electrons can promote a TiS2-based saturable absorber to be an ultrafast switch for a femtosecond pulse output.
ISSN:2040-3364
2040-3372
DOI:10.1039/c8nr01573b