Improved performance of laser written channel waveguides using a TEM/sub 01/* beam

Laser direct writing of single-mode waveguides with a TEM/sub 00/ Gaussian laser beam results in laterally graded refractive index profiles. It is demonstrated that laser direct writing with a TEM/sub 01/*, "doughnut" laser beam produces a more step-like refractive index profile. We show theoretically that the bend loss of the photoinduced waveguides can be significantly reduced, and that the sensitivity of the guided mode parameters to experimental fluctuations in the laser writing process are improved, Differences between the two writing beam cases are assessed experimentally by photodefining curved channel waveguides in the polymeric material system BDK:PMMA.