A new, miniaturized optical system is needed, one that can be integrated on a chip, consumes minimal power, can shift a beam into free space, control the beam shape, and has a tuneable wavefront.
While technology exists to answer each of these points, combining them into a single system has proved elusive until now.
Researchers at TMOS, the Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, have brought this technology one step closer to reality using meta-optics, combining a vertical nanowire with a microring laser made from semiconductor nanostructures.
Vertical nanowires on their own have exceptional directionality and can shape a laser beam effectively, however their configuration results in significant photon leakage during the lasing process. Where the photons reflect of base mirror is also where the nanowire connects to a substrate and that connection makes the nanowire an inefficient laser.
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In a microring laser, on the other hand, most photons in a microring laser travel parallel with the substrate, resulting is less photon leakage and a far higher lasing efficiency, however it is incredibly difficult to control the direction and shape of the beam.
In a world first, TMOS researchers have combined an InP microring laser cavity with a vertical InP nanowire antennae that sits in its centre and directs photon into freespace with specific beam shapes, the development needed for 3D holograms. The microring and the nanowire cavities, which function as the light source and antenna in the system, respectively, are grown simultaneously using the selective area epitaxy technique.
This device is less than 5 microns in size and could eventually form a single hologram pixel. The effectiveness of this coupling has been demonstrated in the lab and details were published in Laser & Photonics Review today.
Lead author Wei Wen Wong says, “This is the way forward towards low power consumption, on-chip microlasers with tunable emission directionality. This new development removes one of the key obstacles standing in the way of realizing 3D holograms.”
TMOS Chief Investigator Hoe Tan says, “The development of dynamic holograms is one of our Centre’s flagship projects. Teams across all five participating universities are working together to make this a reality. The next steps for our research is to create an array of pixels where the wavefront and beam shape can be controlled individually and dynamically tuned.”
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