Broadband conversion of higher order LP_0,m modes to Gaussian beams using silica binary phase plates

We demonstrate conversion of a higher-order LP_0,m mode to a nearly perfect Gaussian beam using silica binary phase plates. The conversion efficiencies obtained are above 60% with corresponding beam propagation parameters of M² < 1.1 of the converted beams for all investigated higher order modes, indicating conversion to an almost perfectly Gaussian beam. We also provide a numerical analysis of the conversion scheme, including bandwidth, both with respect to the conversion efficiency and resulting M². Lastly, we discuss the impact of parasitic modes on the conversion scheme.