Large-energy mode-locked Er-doped fiber laser based Cr2Si2Te6 as a modulator

Abstract

Ultrafast photonic devices based on two-dimensional (2D) materials attract the attentions of researchers. In order to expand the range and diversity of ultrafast lasers and advanced photonics, it is necessary to explore new 2D materials with excellent nonlinear absorption properties. Ferromagnetic insulators (FIs) have the suitable band structure and they can be stripped into single layer structure easily, however, few related works have been reported. In this work, Cr2Si2Te6 (CST) thin film modulator was prepared through the method of liquid-phase exfoliation (LPE) and investigated its nonlinear optical properties and application in obtaining large energy mode-locking pulse output. The modulation depth and saturable intensity of the CST were 4.40% and 12.51 MW/cm2, respectively. Transferring it into the ring cavity, the all-fiber laser can generate a large energy pulse with a center wavelength of 1558.53 nm and a repetition frequency of 1.61 MHz. The energy of single pulse was 53.03 nJ. The maximum average output power was 85.54 mW under the pump power of 1659 mW. To our knowledge, the energy of single pulse is the highest among the reported all-fiber lasers with FIs saturable absorbers (SAs). Our experimental results proved that CST-SA has excellent modulation properties, which provides a basis for future research.