The EU-funded GOSFEL project (Graphene on Silicon Free Electron Laser), demonstrated a new type of compact laser source, which exploits graphene to create a solid-state free electron laser. Compact and low-cost lasers could benefit many indusries, like communications, security, sensors and more.
Free Electron Lasers (FELs) offer an alternative to conventional lasers being potentially the most efficient, high powered and flexible generators of tunable coherent radiation from the ultra-violet to the infrared. However, currently FELs are prohibitively large and expensive. The GOSFEL project used graphene to create a compact, relatively inexpensive, solid-state version of such a laser.
The project’s first priority was to advance a theoretical understanding of the underlying physics and principles, before going on to design and construct a graphene-metamaterial hybrid, functioning as a laser cavity and significantly boosting the light-graphene-interaction.
FELs typically work when electron beams emit radiation by travelling in a vacuum and passing through an undulatory magnetic field. The emission wavelength is established by the electron beam energy and the period of the magnetic field.
Rather than use a magnetic field, the GOSFEL team came up with a new structure, based on patterning of the graphene, to accelerate/decelerate electrons to make them emit radiation in the range of 0.2 to 10 THz. Devices incorporating this structure are currently being tested and the team is confident that they will demonstrate the principle of operation over the next few months. In addition, a new electromagnetic feedback cavity has been developed in parallel and will ultimately be integrated into the device.
According to the team, there was an unexpected consequence of the hybrid device- "The graphene metamaterial hybrid was developed to act as the cavity for the laser, but we found that it also acts as an exiting platform to study the physics of light-matter interactions."
Looking to the future, the team is looking for the right funding, with which to build on these proof-of-principle modulator and detector devices and build prototypes of interest to component and sensor industries.