Quantitative phase measurement of direct laser written waveguides using differential phase contrast

Focused ultrafast laser pulses induce refractive index changes on the micrometer scale in bulk glasses. The structural modifications can be used for the design of customized 3D diffractive optical elements. To characterize these changes the phase of laser written waveguides and planes is measured using the differential phase contrast method. The results are verified by phase measurements of optical fibers with known properties.