Frequency Metrology of Infrared Molecular Spectra : Sources, Techniques, and Applications

Starting from basic concepts, this book provides a comprehensive review of cutting-edge experimental research in the field of infrared precision molecular spectroscopy and absolute frequency metrology. Ranging from the near-infrared to the THz region, state-of-the-art narrow- and broad-band coherent radiation sources with corresponding frequency stabilization methods are described. The most sophisticated high-sensitivity and high-resolution spectroscopic techniques are then discussed, along with an overview of the most recent record-breaking measurements. Relying on improved samples enabled by emerging technologies for producing cold stable molecules, in conjunction with superior frequency standards delivered by modern optical fiber networks, perspectives for further refining spectroscopic performance in terms of ultimate attainable precision are also considered. Finally, exciting new developments are discussed that encompass increasingly refined tests of fundamental physics, quantum metrology and sensing, quantum simulation and computation with ultracold molecules. The book is aimed at researchers passionate about infrared laser sources and molecular spectroscopy, both as a useful guide for the design of advanced experiments and as a text for advanced university courses.

Pasquale Maddaloni graduated in Physics at Federico II University and got his PhD in Physics at the University of Padua for experimental research in the field of Bose-Einstein condensation of atomic gases carried out at LENS (European Laboratory for Non-Linear Spectroscopy). In 2003, he moved to INO-CNR (National Institute of Optics of the National Research Council) in Naples, where he worked on the development of novel infrared radiation sources based on nonlinear optics processes, and their application in frequency-comb-assisted spectroscopy. In 2012, he brought research on buffer gas cooling to Italy, founding the "Cold Molecules" laboratory, which a few years later he connected to the "National Optical Fiber Infrastructure for Time and Frequency Metrology". His current research focuses on the creation of molecule-based quantum sensors of Physics beyond the Standard Model. On an applied level, his skills in precision molecular spectroscopy are directed to environmental monitoring and cultural heritage diagnostics. He is the author of about 100 papers, six book chapters, and a monograph on laser-based frequency measurements. When not working, Pasquale enjoys gardening, listening to music, and spending time with his beloved wife Rosa and children Maria, Bernadette and Massimiliano.

Luigi Consolino was born in Siracusa, Italy, in 1981. Thanks to the constant support of his parents Gaetano and Pina he could accomplish his degree (cum laude) in Physics at the University of Catania (2005), and his diploma (cum laude) at Scuola Superiore di Catania (2005). In 2009, he achieved his Ph.D. in Atomic and Molecular Spectroscopy at LENS. Since 2012 he works at the Italian National Institute for Optics (CNR-INO). His main scientific achievements are related to the far-infrared - THz window of the electromagnetic spectrum, where he has realized experimental setups for spectroscopy, sensing, source and detector characterization, imaging and communication, e.g. measurement of the intrinsic linewidth of a THz QCL, demonstration of a free-standing THz frequency comb (FC), unparalleled accuracy in FC-assisted QCL-based molecular spectroscopy, realization of a RT broadband DFG-based THz spectrometer, new characterization technique for AM-FM THz FCs (FACE), full phase-stabilization of a THz QCL, novel hybrid approach to dual-comb molecular spectroscopy. When not working, Luigi spends most of his time singing in nationally renowned tribute band, snowboarding, and photography, but most of all, enjoying his time with his beloved partner, Silvia, and children Lorenzo and Giulia.

Paolo De Natale is a member of the Directive Council of LENS, Firenze, Italy and acting director of CNR-INO (National Institute of Optics of the National Research Council). In the years 2007-2021, he was director of CNR-INO. Major scientific achievements include: Pioneering pure frequency measurements of fundamental constants in hydrogen and helium; Finding new ways to extend frequency comb synthesizers to the mid and far infrared; Probing the ultimate sensitivity limits of optical fibers; Pioneering laser spectroscopy sensing in geophysics; Unveiling quantum-limited frequency fluctuations in quantum and interband cascade lasers; Inventing a spectroscopic technique, SCAR-Saturated Absorption Cavity Ringdown, pushing molecules detection to 10-15; Discovering new ways to generate frequency combs by nonlinear quadratic processes; Designing high performance laser-based analytical set-ups; Pioneering experiments in Quantum Technologies, at the classical to quantum noise limits. He is author of more than 500 publications, holds 15 patents and is a co-founder of two former CNR spin-off companies, ppqSense srl and QTI srl. He has been a Fellow of SPIE since 2011 and OPTICA (formerly OSA), since 2015.