Abstract
As a means to accomplish high throughput and damage-free processes, non-digitized (analog) diffractive beam splitters are effectual: they can afford fully suppress undesired diffraction beams by containing as much light energy as possible in a fan-out of beams meant for the process. The surface-relief structures of the splitters are designed using a Fourier-iterative algorithm and are formed on high-quality fused silica substrates using direct laser writing and reactive ion etching. For a 13-beam splitter, for example, a non-digitized element gives an efficiency of 97% with S/N=38, whereas a binary counterpart is as efficient as 78 % with S/N=5, where SIN is defined as the ratio between the minimum of the fan-out beam intensities and the maximum of higher-order diffraction intensities. We have tested these two types of elements in laser-machining applications and verified that the non-digitized element produces more satisfying results than the binary element.
