In certain optical materials, processing with femtosecond lasers causes a change of the refractive index at the laser focus. This change can be used to create optical waveguides and diffractive optic elements inside the bulk of a material. In the example on the right, IMRA’s femtosecond fiber laser was used to create a nano-aquarium for studying the movement of micro-organisms. The high peak intensity of femtosecond laser pulse can induce nonlinear absorption in transparent materials such as glass or clear polymers. The absorption occurring at the focal spot inside the transparent material allows the creation of 3D structures by material modification. The material modification fluence threshold is generally deterministic so that features smaller than the focused spot size can be produced.
