||Seeing blue: on the road to new laser technology exploiting 2D metamaterials
Manipulating, controlling and sensing the interaction of light with matter underlies numerous technologies, many of which rely on lasers. Vertical cavity surface-emitting lasers are semiconductor lasers that rely on quantum wells for powerful light emission perpendicular to the wafer surface (in contrast to edge-emitting lasers or light-emitting diodes that emit from the sides or sides and top, respectively). They have unique optoelectronic properties and harness established wafer-fabrication technology for low-cost large-scale manufacture. However, extending their spectral range into the blue and ultraviolet range has been challenging. With the support of the Marie Sklodowska-Curie Actions programme, the MetaVCSEL project is developing technology to achieve this via on-chip beam shaping based on the integration of novel 2D metamaterials.
Vertical cavity surface-emitting lasers (VCSELs) play a key role in the development of modern optoelectronic technologies, thanks to their unique characteristics such as low power consumption, high modulation speed, and large-scale two-dimensional array capability. To further expand the spectral range of VCSELs from the red/near-infrared region down to the blue/UV region is attracting significant interest. This will lead to versatile applications in for example retinal scanning displays, visible light communications, chemical sensing, and sterilization of viruses and bacteria. However, blue/UV VCSELs are suffering from poor beam quality and unstable polarization property due to the lack of effective beam shaping solutions. The recent advances in two-dimensional metamaterials, also known as metasurfaces, open new perspectives for the manipulation of light properties, including amplitude, phase, and polarization with exceptional subwavelength spatial resolution. In particular, the ultra-thin, flat, and compact characteristics of metasurfaces greatly facilitate their integration with semiconductor laser for the development of a miniaturized laser system with a controllable optical wavefront. Seizing on the timely opportunities provided by the latest metasurface technologies, this project aims to develop the very first solution for on-chip beam-shaping blue/UV VCSELs by exploiting metasurface optoelectronic integration, which will unlock the potential to tailor both the phase and polarization properties of blue/UV lasers at an ultra-compact wafer-level. This will give rise to high beam quality lasers with small divergence angle and vector lasers in the blue/UV regime, paying their way toward real-world applications.