Rapid phase plate fabrication using a scanning CO2 laser

Summary form only given. Custom spatial laser profiles such as annular beams have advantages over Gaussian beam profiles for applications including materials processing [1-3], fibre optic communications [4], reduction of nonlinear effects in fibre lasers [5] and optical trapping [6, 7]. Conversion to a desired higher order mode can be done using bulk optics [1-6], however, for some applications a monolithic, integrated solution is desirable. Existing techniques for fabricating structures with nanometer depth resolution onto the output facet of a fibre laser that are capable of high power operation can be slow [7] and sometimes difficult to implement due to critical alignment restrictions [8].We present a novel CO2 laser fabrication technique with in situ beam monitoring capable of fabricating phase plates with nanometre depth resolution. This process is extremely rapid with typical fabrication times of <;10s. A schematic of the system is illustrated in Fig. 1(a).