Patent ID: 7440653

Claim:
A method of writing a waveguiding channel of increased refractive index into a sample, the channel having a width and a path, the method comprising: providing a sample of material having a region which is photosensitive to light of a specific wavelength; generating a spot of light at the specific wavelength, the spot having a static periodic intensity pattern of high and low intensity fringes, and a width which is related to the width of the channel; positioning the spot within the photosensitive region; and causing relative movement between the sample and the light spot with its static periodic intensity pattern along the path of the channel to define the channel by exposing parts of the photosensitive region to the light spot to produce a change in refractive index; and wherein the light spot is generated from polarised light, the method further comprising controlling the polarisation of the light to modify the change in refractive index.