This laboratory is dedicated to the manufacture and study of large quantum systems (also called mesoscopic systems). By nature, these systems are at the frontier between classical and quantum mechanics. Researchers are entering the mesoscopic world when trying for example to miniaturize transistors inside computer chips or to control DNA.
Mesoscopic systems also open new functionalities impossible to obtain from purely classical objects: researchers around the world are trying to construct a quantum computer which could in principle solve mathematically hard problems (like the factorization of large numbers) that classical computers could not tackle.
The present work of the laboratory is dedicated to the study of structures like the quantum cascade laser. The Quantum Cascade Laser (QCL) is a semiconductor laser involving only one type of carriers and which is based on two fundamental phenomena of quantum mechanics, namely tunneling and quantum confinement. It is fabricated by a technique called Molecular Beam Epitaxy in which the layers are "sprayed" one layer at the time.
In this work, Markus Roesch used a terahertz quantum cascade laser heterogeneous stack to produce a spectrum over an octave of spanning enabling the possibilities of numerous applications and self referencing. The full text
Markus Roesch et al., Nature photonics, on-line, doi:10.1038/nphoton.2014.279
We use quantum-cascade-laser frequency combs to demonstrate a high resolution, broadband dual-comb spectrometer.
This article demonstrates the potential of this novel technology. It concludes with the vision of a monolithically integrated mid-infrared dual-comb spectrometer featuring ultra-high sensitivity and selectivity. IRsweep will deliver this technology in an industry ready system.
Dual-comb spectroscopy based on quantum-cascade-laser frequency combs
Gustavo Villares et al., Nature communications 5 Article number: 5192 (2014).
The recent advances in QCL-based frequency combs (A. Hugi et al.) and their application in dual comb spectroscopy (Villares et al.) stimulated the founding of ETH spin-off company IRsweep, where the technology is further pushed towards sensing applications. The co-founders Andreas Hugi and Markus Geiser are also supported by the ETH Pioneer-fellowship program.
The textbook on quantum cascade lasers by Jérôme Faist was reviewed in Physics today. "The invention of QCLs is comprehensively discussed for the first time in Quantum Cascade Lasers..." from Igor Vurgaftman. The full review here
April 2014. Pierre Jouy et al. were offered to make the cover of the 7th May edition of "Analyst" for their contribution to the use of Mid-infrared quantum cascade lasers for liquid and gas spectroscopy. They platform enabled the detection of CO2 isotopes ratio down to 0.02% and a solution of cocaine down to 10ug/mL filtered using a microfluidic system. This work is a collaboration with EMPA, EPFL, Haute Ecole ARC Ingénierie, UNINE and Hochschule für technik FHNW for the IRSens project (Nano-Tera and SNF).
Jan 2014. Markus Roesch was awarded 1ST Place Best Oral Presentation winner for MTh4B.5, "Ultra-broadband THz quantum cascade laser operating with regular comb teeth in continuous wave operation", at Mid-Infrared Coherent Sources (MICS) 2013.
November 2013. Andreas Hugi receives the ETH Medal for Outstanding Doctoral Thesis entitled: Single-mode and Comb Operation of Broadband Quantum Cascade Lasers.
23.10.2013. The European Research Council had to choose the best from no less than 2,400 projects. Happily, the winning researchers, who receive an ERC Advanced Grant, include five from ETH Zurich and Jérôme Faist is among them. In his project, he wants to develop new quantum structures using micro and nano-production technology. It involves a kind of chimera of quantum mechanics: a structure that moves like photons, but interacts like electrons. Faist wants to investigate how abrupt changes in boundary conditions can make ‘virtual photons’ into ‘real photons’, which display behaviour that has not been possible to explain so far. The project aims to enable quantum-optical experiments in the terahertz spectral range and to predict and investigate advanced states of graphene.
07.08.2013. The QCL will turn 20 years in 2014. This will be celebrated with an anniversary workshop in Zurich on 16.1.2014-17.1.2014. Distinguished invited speakers will present achievements and future perspectives for devices and their applications. See http://www.20yearsqcl.ethz.ch for more information.
07.03.2013. A textbook on "Quantum Cascade Lasers" by Jérôme Faist is published by Oxford University Press and already available for preorder for example at Amazon. The ISBN-13 is: 978-0198528241. It covers a wide range from fundamentals to applications and mid-infrared QCLs as well as THz QCLs.
13.12.2012. The recent realisation of an elecrically pumped mid-infrared frequency comb using a quantum cascade laser in the Faist group is published in Nature today. The full article is available here. This work is very relevant for spectroscopy as many small characteistic vibrational-rotational resonances of small molecules are found in this frequency range.
12.12.2012. We are part of Swiss national Competence center for Quantum Science "QSIT". Find out more about this exciting field of research at the Center's website and in this video:
22.06.2012. Europhysics news highlighted Faist group results on Sb-free short wavelength QCLs published in Semicond. Sci. Technol. 27, 045013 (2012). They emphasize the technological importance of sources in the 3-4 µm spectral region that avoid the technical difficulties of Antimony.
07.05.2012. The European Patent Office annually awards the European Inventor Award, honouring outstanding inventours and entrepreneurs. The original QCL patent, based on work of Prof. Jérôme Faist, Prof. Federico Capasso (Harvard University) and coworkers in Bell Labs is among the nominees. The nomination is based on the groundbraking advancements achieved through QCLs which are able to reach areas of the electromagnetic spectrum previously untouched by laser light. Today, the ability of QCLs to produce wide bandwidths, high brightness, and high power very efficiently from a compact source has resulted in an array of unique products, from hand-held sensors for explosives detection and other toxic chemicals, to more powerful radar systems.
03.05.2012. Our recent work on short wavelength Sb-free Quantum Cascade Lasers has been highlighted by Semiconductor Science and Technology. The covered spectral region of 3-4µm is very interesting for e.g. sensing applications. Avoidance of Sb is key for growth and fabrication of lasers. Read more in our research section.
16.03.2012. Semiconductor Today highlighted our demonstration of a 3.3µm Sb-free Quantum Cascade Laser in http://www.semiconductor-today.com/news_items/2012/MAR/ETH_150312.html
15.03.2012. In the so called ultra strong coupling regime, the coupling strength of an electron excitation to a photonic mode can become very large and even comparable to the individual excitation energies. A range of new phenomena is predicted in this regime.
We could demonstrate the to date strongest light matter interaction, by coupling a cyclotron transition of a 2D electron gas to a cavity.
These results are published in Science 335, pp. 1323-1326.
13.03.2012. The Faist Group skiing trip led us to the beautiful "Lenzerheide" resort on this Tuesday. Weather and snow conditions were great. Find a picture of Prof. Faist giving a "ski lesson" on the right.
10.03.2012. Recent work on the ultra strong coupling regime, which can be achieved when coupling parabolic quantum wells to a single mode microcavity is published in Phy. Rev Lett. 108 , 106402.
By using a pseudoharmonic potential, we are able to observe the full coupling strength (Rabi frequency is 27% of the intersubband transition frequency) from cryogenic up to room temperature. In this structure, a depolarization shift is exactly compensated, which is in agreement wich Kohn's theorem. For these reasons, parabolic quantum wells as a very attractive system to study the ultra strong coupling regime.
13.01.2012. Christoph Walther, a recent graduate of the Faist group received the ETH medal in recognition of his extraordinary results. His focus was on low frequency and circuit based Quantum Cascade Lasers. Congratulations!
17.06.2011. Maria Amanti receives the 2011 Swiss Physical Society Award for Applied Physics. Quoting from the laudatio: "Maria has developed as her PhD work a novel approach for cavities of terahertz quantum cascade lasers to overcome processing and conceptual difficulties: By using a dry etching technique, she achieved the fabrication of high aspect ratio ridge structures with a lateral distributed feedback operating as a third order grating which provides at the same time the feedback for the laser mode and the outcoupling to the free space. In this way, a single mode operation was achieved at a frequency defined by the grating periodicity.. Congratulations!
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