Amici direct vision prism. Image by DKuru. CC BYSA 3.0
Scientists have developed a new platform that produces ultrashort UVC laser pulses and detects them at room temperature using atomthin materials. The light flashes last just femtoseconds and can be used to send encoded messages through open space.
The system, from Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS, relies on efficient laser generation and highly responsive sensors that scale well for manufacturing. Together, these advances could accelerate the development of nextgeneration photonic technologies.
The ultrafast UVC laser pulses that last less than a trillionth of a second and can be reliably detected using ultrathin semiconductor sensors. The technology was even used to send messages through free space, hinting at powerful new communication systems.
Photonic technologies
Photonic technologies that operate in the ultraviolet UVC range (100−280 nm) play an important role in fields ranging from superresolution microscopy to optical communications. As these technologies improve, they are expected to open new pathways across science and engineering.
One of UVC light’s most important traits is how strongly it scatters in the atmosphere, which makes it especially useful for nonlineofsight communication. This property allows data to be transmitted even when obstacles block a direct path between sender and receiver. However, despite this promise, progress has been slowed by the lack of practical components capable of working reliably with UVC light.
The new system combines an ultrafast UVC laser source with UVC detectors made from atomicallythin (twodimensional) semiconductors (2DSEM).
To create the laser pulses, the researchers used phasematched secondorder nonlinear processes. This approach relies on cascaded secondharmonic generation within nonlinear crystals, producing UVC pulses that last only femtoseconds, less than 1 trillionth of a second.
Detecting femtosecond pulses
The ultrashort pulses can be detected at room temperature using photodetectors based on the 2DSEM gallium selenide (GaSe) and a wideband gap oxide layer (Ga2O3).
A femtosecond is a unit of time in the International System of Units (SI) equal to 10−15 or 1⁄1 000 000 000 000 000 of a second; that is, one quadrillionth, or one millionth of one billionth, of a second.
To demonstrate the system’s capabilities, the researchers built a freespace communication setup. In this proof of concept, information was encoded into the UVC laser by the sourcetransmitter and then successfully decoded by the 2D semiconductor sensor acting as the receiver.
Future communications
The ability to generate and detect femtosecond UVC laser pulses could have farreaching effects across many advanced applications. The strong sensing performance of 2D materials supports the development of integrated platforms that combine light sources and detectors into a single system. Such platforms could be especially useful for freespace communication between autonomous systems and robotic technologies.
Since these components are compatible with integration in photonic integrated circuits, they may also enable a wide range of future technologies, including broadband imaging and ultrafast spectroscopy operating on femtosecond timescales.
The research features in the journal Light: Science & Applications, with the research paper titled “Fast ultravioletC photonics: generating and sensing laser pulses on femtosecond timescales.”
