Nanosecond laser writing of straight and curved waveguides in silicon with shaped beams

The authors demonstrate a method for transverse writing of optical waveguides in a crystalline silicon wafer using a nanosecond laser with a shaped beam profile that is formed by a pair of cylindrical lenses. In contrast to traditional writing methods, this method avoids forming asymmetric waveguide profiles. Both straight and curved waveguides are written with a nearly circular transverse guide profile and are found to support single-mode propagation for 1550 nm wavelength light. The propagation loss for this wavelength is also measured.