&Bullet; physics 14, s53
By shaping the phase of a light beam, the researchers show that they can guide its way through an otherwise opaque material.
Ravitej Uppu has a mystery – the best materials for housing qubits and certain other optically activated objects usually reflect incident light. By preventing externally applied light from reaching its destination, this reflectivity poses a challenge to the control of optically integrated devices. Now Uppu and colleagues from the University of Twente in the Netherlands have come up with a possible solution to this problem: a way to turn light on to guide any path through a material by structuring the light phase  . According to Uppu, the method the team applied to telecommunication wavelength light should work for light of any color, so the method can be used in devices ranging from chip-based lasers to quantum computers to photonic circuits.
During their demonstration, the Twente team shone an infrared beam into the edge of a 2D silicon crystal that contained a periodic arrangement of air-filled pores. Much of the light was reflected back along the beam, but due to the disorder in the crystal, some of the light was reflected out of the crystal at 90 °. They captured this light with a camera.
The researchers controlled the beam by iteratively modulating the phase of its wavefront. Light captured by the camera indicated the target position of the beam in the sample; This information was then fed into an algorithm that predicted the phase pattern which, if applied to the beam, would allow the light to reach another chosen position. After applying this phasing pattern, they repeated the process to maneuver the light to the next position. The team now plans to build a 3D crystal and add additional cameras to control the light in higher dimensional materials.
– Katherine Wright
Katherine Wright is the assistant editor of physics.
- R. Uppu et al., “Shaping waves spatially in order to penetrate deeply into a forbidden gap” Phys. Rev. Lett.126177402 (2021).