Light-emitting displays are everywhere in everyday life. Next-generation optical systems need miniaturised, compact and energy-efficient light sources that can be easily integrated onto micro/nano-electronic platforms. The properties of the emitted beams must also be easily manipulated in terms of colour (frequency), coherence, polarisation, direction and spatial profile.

This requires a fundamentally new approach to light sources, comparable to the leap from light bulbs to solid-state lighting using LEDs. Meta-optics provides the opportunity to revolutionise this technology. Arrays of nanoscale emitters can be fabricated using current integrated circuits technology, where collectively these sources can be dynamically driven to emit light with the properties they are designed for.

These nanoscale light sources can be used in a range of technology products. For example, they could fill the technology gap that has left dynamic holograms largely in the realm of science fiction, or they could be used for the next generation wireless optical networking technology (LiFi) that uses advanced LEDs for ultra-high speed data transmission.

Key challenges are the development of the nano-scale laser arrays with the desired properties that can be dynamically tuned and ultra-compact systems over large areas.

The Generate Theme focuses on developing these new meta-optical light emitters. We are currently researching nanoscale lasing meta-optics, exploring nanowires and atomically thin (2D) materials as gain medium; deterministic generation of quantum light sources with high purity based on single defects in 2D materials; new design of III-V nanowires for flexible and tuneable LEDs.

Together we will provide the brightest and most efficient miniaturised classical and quantum light sources.

Recent achievements 

  • First portable single photon source, based on a 2D material (hBN)
  • New generation of quantum emitters at the blue spectral range
  • First demonstration of spin-photon interface, at room temperature, of a quantum emitter in hBN
  • New method for nonlinear frequency conversion with high efficiency
  • First demonstration of spatially entangled photon pairs with metasurfaces

Subprogram 1A – Nanoscale Lasers and Laser Arrays  

In Theme 1A, our aims include electrical nanolasers, tailorable emission and coupled nanolaser arrays. These aspects are critical in practical devices and in many applications such as holograms and optical sensing.

Progress in fundamental nanolaser building blocks include the development of uniform GaN nanopillar arrays, grown with precise control on dimensions and with smooth crystal facets on sidewalls. GaN material is conducive for UV and blue emitters, while the nanopillar geometry simultaneously forms a nanoscale Fabry-Perot cavity to enable lasing.

A transfer process and device fabrication scheme has been developed for ultrathin semiconductor films, with a successful fabrication of a 230 nm-thick LED emitting at an optical communications wavelength of 1550 nm. In future work, such film can be modified to create an electrical metamaterial laser that can enable tailoring of emission properties such as direction, polarisation wavelength etc.

A unique hybrid nanolaser array system has been demonstrated, where Fabry-Perot and random lasing modes coexist at the same time. Furthermore, by changing the operating temperature, the dominating mode could be selected, and thereby the emission properties as well. These lasers are made of GaAs nanowires, where a random array enabled random lasing and the nanowire dimensions enabled Fabry-Perot lasing.

Controllable emission direction has been demonstrated in microring lasers. In a typical case, microring lasers emit light in-plane, which is useful in photonic integrated circuits, for example. By coupling the microrings to nanoantennas, directional, out-of-plane emission was achieved, which can be exploited in optical sensing, LIDARs and holograms among other applications.

Action Items for 2023

  • Optimising cavity design, transparent contacts, and fabrication challenges
  • Electrical injection to microring cavity
  • Develop the theoretical approaches for PT symmetry-based control of gain and loss
  • Light-emitting metasurface design and fabrication with electrical injection
  • Demonstration of NIR-to-visible conversion with coupled metamaterial and upconverting nanoparticles 0.1nW/cm2

Subprogram 1B – Advanced and Quantum Light Sources

Advanced and quantum light sources are essential to optical imaging and various quantum applications. This research program aims to explore the efficient conversion of light colour, emission of quantum light, and generation of spooky photons using metasurfaces.

A novel approach to achieve effective nonlinear sum-frequency generation in multi-resonant GaP metasurfaces has been presented. Our research shows potential in controlling the emission to various diffraction orders by changing the polarisation of the input pump beam, creating new possibilities for infrared to visible light conversion with nonlinear light sources.

The first ultrabright source of single photons packaged into a portable box has been produces, with purity exceeding 99%. This was presented to the NSW Chief Scientist as a novel capability that was totally Australian-developed and was led by the Centre.

A new generation of quantum emitters at the blue spectral range has been developed along with the first demonstration of the room-temperature spin-photon interface of a quantum emitter in hBN. 

Generation of spooky phontons has been achieved with nonlinear metasurfaces producing nanometer thickness quantum light source with spatial entanglement. This device does not require temperature control and allows flexible tuning of photon wavelength and emission angle. The practical features of the device will make it an important part of upcoming micro-quantum technologies.

Action Items for 2023

  • Enhancement of nonlinear emission from 2D materials studies and their heterostructures
  • Initial characterisation of quantum dots based sources in near infrared
  • Study of second-harmonic generation in individual GaN nanowires
  • Generation of polarisation-entangled photon pairs
  • Hyper-entanglement in spatial and spectral degrees of freedom with nonlinear metasurfaces