High-speed spatial control of the intensity, phase and polarisation of vector beams using a digital micro-mirror device

High-speed spatial control of the intensity, phase and polarisation of vector beams using a digital micro-mirror device

The dynamic spatial control of light fields is essential to a range of applications, from microscopy to optical micro-manipulation and communications. Here we describe the use of a single digital micro-mirror device (DMD) to generate and rapidly switch vector beams with spatially controllable intensity, phase and polarisation. We demonstrate local spatial control over linear, elliptical and circular polarisation, allowing the generation of radially and azimuthally polarised beams and Poincaré beams. All of these can be switched at rates of up to 4kHz (limited only by our DMD model), a rate ～2 orders of magnitude faster than the switching speeds of typical phase-only spatial light modulators. The polarisation state of the generated beams is characterised with spatially resolved Stokes measurements. We also describe detail of technical considerations when using a DMD, and quantify the mode capacity and efficiency of the beam generation. The high-speed switching capabilities of this method will be particularly useful for the control of light propagation through complex media such as multimode fibers, where rapid spatial modulation of intensity, phase and polarisation is required.