Improved SLMs Make for Better Holographic Displays

Spatial Light Modulators (SLMs), devices that convert electrical signals into modulated light, enable a range of applications in optical imaging, information processing and communications. Now, improvements in the technology are leading a company based in Leuven, Belgium to new applications in holography.

SLMs are adept at modulating key properties of light, including amplitude, phase, and polarisation. While mechanical systems like digital micromirror devices offer rapid light control, their binary operation limits their ability to provide customised modulation, particularly for phase and polarisation.

On the other hand, SLMs based on liquid crystal (LC) technology can perform more complex modulation tasks, making them ideal for applications requiring high resolution and phase modulation.

In an LC SLM, the orientation of liquid crystal molecules can be controlled by applying electric fields. When no field is applied, ie. when the SLM is ‘off’, the molecules all line up in a particular direction in the LC layer of the device. When an electric field is applied through the LC layer, the orientation of the liquid crystal molecules can be manipulated. The electric field exerts forces on the molecules, causing them to reorient themselves in a defined way.