Improved performance of laser written channel waveguides using a TEM01* beam

Laser direct writing of single-mode waveguides with a TEM00 Gaussian laser beam results in laterally graded refractive index profiles. It is demonstra ted that laser direct writing with a TEM01* "doughnut" laser beam produces a more steplike refractive index profile. We show theoretically that the be nd loss of the photoinduced waveguides can be significantly reduced, and th at the sensitivity of the guided mode parameters to experimental fluctuatio ns in the laser writing process are improved. Differences between the two w riting beam cases are assessed experimentally by photodefining curved chann el waveguides in the polymeric material system BDK:PMMA.