From Lasers to Superconductors: The Optoelectronics Chip Revolution Begins

Superconductivity in K3C60  Thin Films:

A study published November 9 in the scientific journal Nature Communications reveals interesting findings on superconductivity in K3C60 thin films. This research shows that the electrical response of photoexcited K3C60 is nonlinear, that is, the resistance of the sample varies depending on the applied current. This is an important feature of superconductivity and confirms some of the previous observations. Additionally, it provides new information and perspectives on the physical properties of K3C60 thin films.


Advancements in Optical Manipulation of Materials

Producing superconductivity at high temperatures through optical manipulation of materials is one of the main research focuses. So far, this strategy has been successful in several quantum materials, including cuprates (a class of compounds containing copper (Cu) atoms within an anion), k-(ET)2-X, and K3C60. Increased electrical compliance and loss of resistance have been observed in optically guided states in these materials.


(Measurement setup, in which mid-infrared and visible beams are focused onto the optoelectronic device.)


On-Chip Non-Linear THz Spectroscopy:

In this study, researchers used on-chip nonlinear THz spectroscopy to open the field of picosecond transmission measurements (a picosecond is one trillionth of a second). They coupled thin films of K3C60 to photoconductive switches with coplanar waveguides. Using a visible laser pulse to trigger the switch, they sent a powerful pulse of electrical current through the material, lasting only a picosecond. After traveling through the solid at about half the speed of light, the current pulse reached another switch that acted as a detector, revealing important information such as the characteristic electrical signatures of superconductivity.


Future Prospects

This particular setup on the chip was designed and manufactured in-house. "It is an excellent tool for studying non-equilibrium nonlinear transfer phenomena such as nonlinear and anomalous Hall effects, Andreev reflection, and others," said lead author Eryin Wang, a staff scientist at Cavalleri. "We developed a technical platform," he says. The group also notes that the integration of nonequilibrium superconductivity into opto-electronic platforms could lead to new devices based on this effect.