The Tunable Intermodal Interference And Talbot Effect By Optofluidics

Optofluidics is a new optical manipulating technology,which can be used to manipulate liquid and particles at micro-nano scale,to realise the optical imaging and particle manipulating.Optofluidics introduce microfluidics into the traditional optics,manipulating the diffusion of the liquid to control the route of laser,and then realise the functions of optical devices.Compared with the traditional solid optical devices,optofluidic devices introduce liquid materials,which increase the flexibility of the experiment.It can regulate the properties of optical devices instantly,which is convenient and efficient to use.Optofluidics can implement the refractive index distribution we need by controlling the diffusion of the fluid,then the optical deflection will also be realized and we can get the optical image required.Optofluidics can also control the laser by controlling the focal length of the liquid lens,therefore forming the "optical tweezers" based on the light force to capture the particles range from micrometers to nanometers.It can be used in particle separation and detection.The Talbot effect is a kind of periodic phenomenon when light is exposed on a raster,known as a typical self-imaging phenomenon.This phenomenon can be realized when light passes through the waveguide with gradient refractive index.It is difficult to prepare gradient refractive index in the traditional solid optical devices,though we can use the external pressure to prepare refractive index distribution,it is difficult to realize smooth refractive index distribution.The optofluidic devices introduce liquid with different refractive indexes in tiny space,realizing the smooth refractive index distribution by the diffusion of liquid.Optofluidics also makes it possible to control the distribution of refractive index by controlling the flow velocity and the liquid,therefore the distribution can be realized conveniently,quickly and efficiently,so as different optical patterns.The optical devices such as couplers and beam splitters which use optofluidics will be developed rapidly in the future.This paper introduced a method for the realization of the Talbot Effect and the intermodal interference in the liquid diffusion optofluidic waveguides.We simulate the liquid diffusion and the optical images in the optofluidic waveguides.After that we analyze the relationship between the waveguide starting conditions and the laser propagation in the Talbot effect and the intermodal interference.We found that the optical images are affected by waveguide geometry,entrance velocity,entrance velocity ratio,entrance width and the liquid species.Therefore different images of the Talbot effect and the intermodal interference can be designed by changing the liquid-diffusion waveguide starting conditions.We analysed the initial parameters that influence the Talbot effect and the intermodal interference and this method can be used to design new optofluidic waveguides in the future.