Instituto de Óptica “Daza de Valdés”

A Route to Ultra-Fast Amplitude-Only Spatial Light Modulation using Phase-Change Materials

Laser Processing Group (LPG)

Madrid / July 27, 2023

A team of researchers from Center for Research and Innovation in Metamaterials of the University of Exeter and the Laser Processing Group of the Institute of Optics has presented in the journal Advanced Optical Materials a new unique spatial light modulator of its kind, capable of modulating the potentially ultrafast light and only in amplitude (without inducing changes in phase). This innovative technology is based on phase change chalcogenide materials and achieves improvements that can be exploited in fields such as wave front formation, communications, detection and grayscale imaging.
The device consists of a thin GeTe layer, and operates like a reconfigurable mirror where by changing the material between its amorphous and crystalline states, a gradual change of the amplitude of the reflected light becomes accesible without modifying the optical phase.
A wave reaches the right wall, and it is seen that two waves are reflected, a large one at the top of the wall and a small one at the bottom.

Why is it important not to affect the optical phase?

Discrete, amplitude-only modulation of light can increase the degrees of freedom of wavefront shaping experiments, by combining such devices with their phase-only counter-parts based on liquid crystals.
The experimental results show an absolute intensity modulation of 38% (relative modulation of 233%), with a minimal shift in the optical phase of less than ≈π/50 along the measured areas. Moreover, the cycling of GeTe and other chalcogenides of its family is inherently fast, offering rapid transition rates of the order of nanoseconds or less (i.e. faster than current liquid cristal technologies).
The research team stresses that this work paves the way for the development of a new class of ultrafast, non-volatile, and energy-efficient spatial amplitude modulators. In addition, the device ease of fabrication combined with its inerently rapid switching speeds would allow its integration in electrically controlled pixelated devices.

Comunicación IO-CSIC
cultura.io@io.cfmac.csic.es

Related news

Suscription

Privacy Overview

This website uses cookies so that we can provide you with the best user experience possible. Cookie information is stored in your browser and performs functions such as recognising you when you return to our website and helping our team to understand which sections of the website you find most interesting and useful.