The Quantum Cascade Laser Turns 30 Years Old

From its first “ignition” at Bell Labs in the USA 30 years ago, the Quantum Cascade Laser has paved the way for a vast number of applications across the electromagnetic spectrum, covering wavelengths from the microwave region to the infrared. A conference organized by CNR, featuring specialists from around the world in the fields of photonics, quantum sciences, and nanofabrication, is currently celebrating the significant advancements achieved by this technology while looking towards the future of a “quantum by design” laser. The celebratory events will conclude with the mid-term meeting of the new Research Infrastructure I-PHOQS, focused on these strategic themes.

Currently taking place in Ischia is a dual event to celebrate the 30th anniversary of the Quantum Cascade Laser and its applications, which represent frontiers in science and technology. This includes the International Quantum Cascade Laser School & Workshop 2024 (IQCLSW 2024), organized by two institutes of the National Research Council (CNR), the National Institute of Optics (CNR-INO), and the Nanoscience Institute (CNR-Nano), along with the University of California (UCLA). The event will continue on August 30 and 31 with the meeting of the Research Infrastructure I-PHOQS (Integrated Infrastructure Initiative in Photonics and Quantum Science), which involves CNR and PoliMi, with eight locations across Italy, funded by the PNRR as a large network of four pre-existing infrastructures: LENS, CUSBO, ELI, and Beyond-Nano.

Quantum Cascade Lasers (QCLs) are miniaturized semiconductor light sources, among the most versatile and powerful operating in the infrared. Their evolving application fields include security, process and quality control, biomedicine, cultural heritage, the environment, and space. Italy boasts excellent expertise in this technology, thanks to contributions from entities like CNR, making it a reference point in the international landscape. Many young people are present at these two events, confirming that the advanced training of new talents is essential not only for frontier research but also for innovation and the future of society. The dual event involves scholars from around the world to outline future scenarios in highly strategic sectors, as emphasized by Paolo De Natale, research director at CNR-INO in Florence, Chair of IQCLSW 2024, and scientific coordinator of I-PHOQS: “Lasers, and particularly QCLs that cover almost the entire infrared spectrum, are an essential enabling technology for increasingly strategic sectors such as Quantum Technologies, promising significant innovations and social and economic progress on a global scale”.

Miriam Serena Vitiello, research director at CNR-Nano in Pisa and another Chair of IQCLSW 2024, highlights that “Thanks to CNR’s infrastructural enhancements, QCLs can now be developed entirely in Italy: from complex design to custom-built quantum materials to nanometer-scale assembly. This is a remarkable technological achievement that allows our researchers to explore enormous prospects, for example, in sensor technology, nanoscale imaging, and secure communications”. CNR has consolidated excellent expertise and has contributed to significant technological and scientific advancements in this sector. Among these is the first quantum cascade laser operating at Terahertz frequencies; one of the co-inventors of the quantum cascade laser based on superlattices of semiconductor materials is Gaetano Scamarcio from CNR-Nano. Among the many European projects that CNR has secured to advance research on quantum cascade lasers and their development for various practical applications are three prestigious grants from the European Research Council (ERC) won by Miriam Vitiello from CNR-Nano, and the EU projects of the Quantum Flagship led by Paolo De Natale’s group at CNR-INO.

Quantum Cascade Laser
The quantum cascade laser is an advanced and innovative technology that exploits quantum phenomena to generate laser light with extreme precision. Unlike traditional lasers, which emit light over a broader range of frequencies, quantum cascade lasers emit very precise and controlled radiation in the mid and far infrared band (infrared is also known as thermal radiation, and it lies between microwaves and visible light). This is made possible by a unique operating mechanism: an internal structure composed of layers of semiconductors allows light to “jump” through multiple stages of emission, creating a cascading effect that amplifies the light signal very effectively.

First experimented in 1994 by Federico Capasso and his team at Bell Laboratories, the quantum cascade laser has had a remarkable impact on photonics and has opened new possibilities for scientific and industrial applications requiring high precision and sensitivity. For example, in spectroscopy for chemical and environmental analysis (detecting trace gases and pollutants with high accuracy), in sectors such as security (detection of explosives and narcotics), in long-distance optical communication, in advanced medical imaging, and diagnostics (clinical analyses and breath tests, oncological diagnoses). Italy actively contributes to this field with significant research and innovations, thanks to the work of research institutions and universities that develop and apply these cutting-edge technologies.

Info:

Elisabetta Baldanzi, Cnr-Ino.

Paolo De Natale, coordinatore scientifico I-PHOQS, Cnr-Ino.

Maddalena Scandola, Ufficio Comunicazione Cnr-Nano.

Miriam Vitiello, Cnr-Nano.