ICFO researchers present high-power light source transmitting across seven octaves

15 Dec 2022

Tabletop source spans UV-THz wavelengths and is five times brighter than most powerful synchrotrons.

Researchers at ICFO, Barcelona, Spain, have developed a very bright light source that covers seven optical octaves — from ultraviolet to terahertz wavelengths. The tabletop coherent source features a spectral brightness up to five orders of magnitude higher than the brightest synchrotrons, which are large facilities.

By removing the need for mechanically tuning or synchronizing numerous narrow spectrum sources, the new source enables a wide variety of strong field, ultrafast and molecular spectroscopy applications. For instance, simultaneously identifying toxic molecular compounds in pharmaceuticals with high precision or investigating the origins of high-temperature superconductivity.

Lenard Vamos, Ph.D. from ICFO – The Institute of Photonic Sciences has presented his group’s new research at the Optica Laser Congress, 11 – 15 December, in Barcelona, Spain.

The presentation is entitled High Brightness 7-Octave-Spanning Coherent Light Source.

Dr. Vamos commented, “The combined coherent spectral bandwidth and high brightness allow to implement new hyperspectral ultrafast spectroscopies without timing jitter. This will allow to pump and probe charge and nuclear dynamics in atoms, molecules, liquids and solids with unprecedented precision.”

Broadening spectral range

The researchers combined three nonlinear techniques to achieve a spectral range from 340 to 40,000 nm, which would allow one source to be used for numerous molecular spectroscopy applications. First soliton self-compression and dispersive wave generation in an anti-resonant-reflection photonic crystal fiber are used to achieve a short pulse of 3.5 fs and an extreme supercontinuum from 340 to 6000 nm. Intrapulse difference frequency generation is then applied to broaden the output spectrum to 40,000 nm.

The source’s spectral intensity can be tuned to the range most useful for a specific experiment by changing the soliton self-compression pressure. For example, the authors showed that pressures above 25 bar (2500kPa) provide a bright UV output between 340 to 360 nm. They also demonstrate UV peak powers up to 2.5 MW and THz peak powers of 1.8 MW.

Dr. Vamos added, “We are presently using this source to optically probe nonlinear signatures of quantum phase transitions in quantum materials such as a high-Tc superconductor. Here, we already showed that such a source can directly identify the various quantum properties of such a complex material.”