Femtosecond Laser Micro Processing Lithium Tantalate Waveguide And Characteristics Of Research

Quantum information science is a new field of science formed by cross fields of quantum optics and information technology. In recent years, quantum information has brought new challenges along with opportunities to classical information science. The development of quantum information enriched theory of quantum optics in turn. This paper mainly discusses one of the most important applications of quantum optics: femtosecond laser direct written waveguides and integrated devices, what’s more, we also researched the combination of quantum optics and material science-the two photon interference experiment, commonly known as Hong-Ou-Mandel experiment to confirm that magnetic plasmon materials may hold quantum properties.Femtosecond laser fabrication technology is a newly developed and very promising way to achieve micro-fabrication. It is fast,cost saving,more convenient than traditional waveguide fabrication methods, and many expand to three dimensional waveguide machining. Especially,it requires no lithography,which greatly shortens the period from ideas to reality. However, researches in this field mainly focus on waveguide machining inside silica and lithium niobate. Writing laser sources is limited to laser with repetition rate lower than lMHz.There is a lack of reports both on laser of higher repetition rates,and waveguide writing inside lithium tantalate. This paper exploits waveguide fabrication parameters with80MHz high repetition rate inside lithium tantalate, and observes optical properties of the waveguides made. Then we carry out design of quantum chips based on femtosecond laser written waveguides. The paper is constructed as follows:l.We systematically introduced research achievements on femtosecond laser micro-machining. This technique employs complicated interaction processes,with multiple and entangled fabrication parameters,is a vast and promising research field.The paper analyzes the impact of different writing parameters,like pulse energy, repetition rate,and writing velocity,on quality of waveguides written.Make an introduction to different types of laser written waveguides,together with directional coupler.2.We constructed and aligned the femtosecond laser micro-maching system,which is based on one airbearing high resolution motor, with accuracy up to200nm ensuring qulity and smoothness of waeveguides fabricated upon it.The system is capable of waveguide device writing,inspecting,and coupling.. Then we made our own LiTiO3waveguides,and evaluated quality of waveguide written.The results show that with the light source of80MHz,147fs,800nm femtosecond laser,pulse energy of6.5nJ and writing velocity at O.1mm/s are the right writing parameters for type I,while9.5nJ with15micrometers spacing and11.3nJ with13micrometers spacing at O.lmm/s are better for type II. All the waveguides written like that is single mode.3.We successfully fabricated directional couplers inside LitaO3,and measured its splitting ratio,which laid solid foundation for quantum chips.4. We observed Cerenkov radiation and generation of white light in femtosecond laser pumped priodicaly poled LiTiO3.5.We carried out a fiber based Hong-Ou-Mandel two photon interference experiment which testifiedthat two-dimensional meta-material sample hold quantum properties.