Opto-mechanical Effects In Liquid Metal Core Optofluidic Microbubble Cavities

Optomechanical effects is a phenomenon that the optical field driver in optical devices vibrates mechanically.WGM mode microcavity has many advantages,such as high Q value,small mode volume and high energy density.At the same time,it also has many advantages,such as typical double neck micro circulation and integration.It has attracted extensive attention and has become a research hotspot in the field of optical microcavity optomechanical effect.The work of this paper gives full play to the role of microfluidic channel in optical microfluidic microcavity,combines different liquid metals with optical microfluidic microcavity,fully studies the optomechanical coupling effects of solid-liquid coupling system,and interprets the solid to liquid phase transition and supercooling characteristics of liquid metals by means of Optics and optomechanics.The research results and innovations of this paper are as follows:1.Firstly,the liquid metal core optofluidic microbubble microcavity was characterized,and the hybrid optical-surface plasma mode of a liquid metal core optofluidic microbubble cavity was investigated.Experimentally,in a relatively thin-walled liquid metal core hybrid microcavity.The existence of a liquid metal surface plasma as well as a hybrid mode was confirmed by controlling the polarisation state of the pumped light and combining it with theoretical analysis.Further hybrid optical modes with quality factors of 10~3-10~7were obtained by adjusting the microcavity wall thickness.2.The opto-mechanical modes of two different phases was studied,that is,the solid acoustic mode(SAM)confined in silica shell and the liquid breathing mode(LBM)in liquid metal;Firstly,we realize the thermal tuning of two optomechanical modes through ohmic heating.It was proved that the mechanical frequency shift of SAM and LBM depends on the young’s modulus and Poisson’s ratio of silica and the sound velocity and density of liquid metal respectively,and the relative tuning ranges are 0.296MHz and0.227MHz respectively;On this basis,we further study the coupling between SAM and LBM.Theoretically,we propose a general theory of coherent coupling and dissipative coupling between SAM and LBM,and reveal the physical mechanism of energy level attraction and repulsion between the two mechanical modes.Experimentally,thanks to the ultra wide range adjustability of liquid metal core microcavity,the coupling between SAM and LBM is realized through ohmic thermal tuning.The coupling strength between them depends on the laser pump power.Controlling the pump power realizes the coherent coupling and dissipative coupling between the two optomechanical modes.3.The phase transition material is combined with an optofluidic microbubble cavity to study the solid-liquid phase transition of the material by optical and photomechanical methods.In the experiments,the transient processes of solid-liquid phase transition and liquid-solid phase transition of Gallium metal were investigated by monitoring the wavelength of the composite mode,taking Gallium metal with low melting point(29.8°C)as an example.The solidification temperature of gallium metal decreases as the initial temperature increases,but its melting point is not affected by the initial temperature;we have also studied the solid-liquid phase transition of gallium by using the photomechanical mode,which enables the reversible manipulation of the photomechanical mode and provides an additional dimension and method for studying the solid-liquid phase transition of matter.