Precision laser processing of optical microstructures with slab waveguide CO₂ lasers

High precision laser direct writing of two types of micro-optical structure is demonstrated using a workstation built around a commercial CO₂ slab waveguide laser. Drift and fluctuations in beam pointing, beam shape and pulse energy are quantified, providing an understanding of the precision capabilities. Quartz glass ablation by waveguide laser pulses of width in the 20 to 60 µs range has been characterized and a refractive microlens machined, involving material removal to a depth of 70 µm. Surface structures in aluminum with 143 µm lattice spacing have been produced to act as two dimensional photonic bandgap devices, modifying the transmission properties of hollow planar waveguides in the mid-infrared.