A method of producing an arbitrary complex field modulation by use of two pixels of an analog ferroelectric spatial light modulator (SLM) is demonstrated. The method uses the gray-scale modulation capabilities of a SLM to spatially encode the complex data on two pixels. A spatial filter is used to remove the carrier signal. This technique gives fast gray-level amplitude and phase modulation.
The paper reports the first experimental demonstration of full complex modulation of a coherent wavefront on a spatial light modulator invented by Birch. The work results from an EPSRC ROPA (GR/L71230/01) award on which I was the researcher. This has several applications in research such as our digital/optical correlator system (currently being developed by the Indian Institute of Technology (joby@physics.iitd.ernet.in), and Richard Hartman (hartman@aos-inc.com) of AOS Inc following our work). Previous systems could only implement phase, limiting their performance. It was one of the first uses of the BNS analogue SLM (info@bnonlinear.com) and is used to market their SLMs.