Nonlinear Optical Properties of Zirconium Diselenide and Its Ultra-Fast Modulator Application

Wang Wang,Chen Chen,Zhang Zhang,Guo Guo,Zheng Zheng,Li Li

doi:10.3390/nano9101419

Abstract

Recently, two-dimensional (2D) materials have been widely studied by researchers due to their exceptional 2D structure and excellent optical characteristics. As one of the typically-layered 2D transition metal dichalcogenide (TMD) semiconductors from group IVB with a bandgap value of 0.9–1.2 eV (bulk to monolayer), the characteristics of zirconium diselenide (ZrSe2) have already been extensively investigated in many fields. However, the nonlinear absorption properties of ZrSe2 in ultra-fast lasers have not been previously demonstrated. In this work, we measured various parameters in order to investigate the characteristics of the nonlinear saturable absorption of ZrSe2. A ZrSe2–polyvinyl alcohol (PVA) film was successfully prepared, which was employed as a saturable absorber (SA) to demonstrate, for the first time, an erbium (Er)-doped passive mode-locking fiber laser with a ring cavity. The saturation intensity of the ZrSe2–PVA film-type SA is 12.72 MW/cm2, while its modulation depth is 2.3%. The stable soliton state with a maximum output power of 11.37 mW and a narrowest monopulse duration of 12.5 ps at a repetition frequency of 21.22 MHz was detected. The experimental results conclusively proved that ZrSe2, with its suitable bandgap value and excellent nonlinear absorption properties, as well as its high damage threshold, should have extensive potential applications within the field of ultra-fast pulse lasers.

Highlights

Mode-locked fiber lasers have been arousing the extensive interest of many researchers due to their value in a variety of applications in the fields of basic science, fiber telecommunications, industrial materials processing, precise optical metrology, biomedical imaging, and others [1,2,3,4,5,6,7,8,9,10]
It is well known that the surface morphology characteristics of the samples used in our experiment are important for analyzing the performance of the saturable absorber (SA)
After the ZrSe2–polyvinyl alcohol (PVA) SA was inserted into the ring cavity, the stable mode-locking state was found by carefully changing the polarization controllers (PCs) under the pump power of 351 mW, which suggested that the pulse generations could be attributed to the nonlinear absorption of the SA

Summary

Introduction

Mode-locked fiber lasers have been arousing the extensive interest of many researchers due to their value in a variety of applications in the fields of basic science, fiber telecommunications, industrial materials processing, precise optical metrology, biomedical imaging, and others [1,2,3,4,5,6,7,8,9,10]. Compared to the actively mode-locked method, the passively mode-locked technique has more attractive advantages, such as no requirement for modulators, low cost, a compact structure, good stability, etc. It has been desired for a variety of studies and applications [9,11]. The nonlinear optical element, called a saturable absorber (SA), is one of the key devices for achieving various ultra-short pulse trains and enhancing the stability of the environment in a passively mode-locking fiber laser [4,12]. The study of novel and high performance SAs has always been the focus of ultrafast laser research

Methods

Results

Conclusion