Tin Diselenide Coated Micro Fiber And Its Broadband All-optical Intensity Modulation Characteristics

With the rapid development of optical fiber communication and other applications based on optical fibers,high performance solutions of optical modulation are indispensable.Among the fiber-based devices,microfiber(MF)devices have attracted increasing attention since their extensively applications in the fields of fiber optic sensing and modulating.MF is a kind of fiber with a waist diameter in micrometers,which is fabricated by flame-stretching a standard fiber.The strong evanescent field of MF could greatly enhance the light-matter interaction,thus MF is a promising candidate for fabricating high performance all-optical modulators.Tin diselenide(SnSe₂)is a kind of transition metal chalcogenides(TMDs)with layered structure,which belongs to the graphene-like two dimensional materials.Due to its unique optoelectronic characteristics like strong absorption properties and high carrier mobility,SnSe₂ is also a promising candidate in the applications of high performance optical modulating devices.In this paper,a broadband fiber-based all-optical modulator is fabricated.By using different pump lights,the broadband all-optical modulation characteristics of SnSe₂ coated MF structure are investigated in this paper.In addition,the response time measurements of this structure are also performed.In the experiment of employing 405/532/660 nm laser as external pump light,the output transmitted power variation of SnSe₂ coated MF structure in the range of 1520-1620 nm is investigated.Under the 405,532 and 660 nm pump light illuminations,the maximum transmitted power variations of SnSe₂ coated MF structure are⁴.2 dB,4.12 dB and 3.15 dB,respectively.Correspondingly,the maximum modulation efficiencies of SnSe₂ coated MF structure are⁰.30735 dB/mW,0.20226 dB/mW and 0.11509 dB/mW.In addition,the response time of the SnSe₂ coated MF structure under different 405/532/660 nm pump lights are also investigated.Under the 405,532 and 660 nm pump light illuminations,the measured response time of SnSe₂coated MF structure are 4.2/4.1 ms,4.9/4.7 ms and 3.7/3.9 ms,respectively.According to the above-mentioned experimental results,the structure we fabricated has a good response in terms of all-optical modulation functionality.By using the finite element method in COMSOL,we also investigate the optical transmission characteristics of SnSe₂ coated MF structure.The refractive index of SnSe₂ can be changed when the pump light illuminated on the SnSe₂,which can also change the refractive index of SnSe₂-MF hybrid waveguide.Therefore,the optical transmitted power of SnSe₂ coated MF structure would be modulated.The simulated results indicate that a larger optical power is detected under the increasing 405,532 and 660 nm pump lights which are consistent with the experimental results.What is more,the all-optical modulation efficiencies of SnSe₂ coated MF structure under different transmitted light wavelengths are analyzed.The innovations of this paper include:1.A fiber-optic modulator combing 2D SnSe₂ and MF is proposed to realize broadband all-optical modulation functionalities with high efficiency under the pump lights(order of mW).2.The broadband(1520-1620 nm)all-optical modulating characteristics of the SnSe₂ coated MF structure with external pump lights(?=405/532/660 nm)are theoretically and experimentally verified.