Scientific Results

Optical Frequency Combs in Quadratically Nonlinear Resonators

Year: 2020

Authors: Ricciardi I., Mosca S., Parisi M., Leo F., Hansson T., Erkintalo M., Maddaloni P., De Natale P., Wabnitz S., De Rosa M.

Autors Affiliation: CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, I-80078 Pozzuoli (NA), Italy; INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Napoli, Complesso Universitario di M.S. Angelo, Via Cintia, 80126 Napoli, Italy; OPERA-photonics, Université libre de Bruxelles, 50 Avenue F. D. Roosevelt, CP 194/5, B-1050 Bruxelles, Belgium; Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden; The Dodd-Walls Centre for Photonic and Quantum Technologies, Auckland 1142, New Zealand; Physics Department, The University of Auckland, Auckland 1142, New Zealand; CNR-INO, Istituto Nazionale di Ottica, Largo E. Fermi 6, I-50125 Firenze, Italy; Dipartimento di Ingegneria dell’Informazione, Elettronica e Telecomunicazioni, Sapienza Università di
Roma- Via Eudossiana 18, I-00184 Roma, Italy; Department of Physics, Novosibirsk State University, 1 Pirogova Street, Novosibirsk 630090, Russia

Abstract: Optical frequency combs are one of the most remarkable inventions in recent decades. Originally conceived as the spectral counterpart of the train of short pulses emitted by mode-locked lasers, frequency combs have also been subsequently generated in continuously pumped microresonators, through third-order parametric processes. Quite recently, direct generation of optical frequency combs has been demonstrated in continuous-wave laser-pumped optical resonators with a second-order nonlinear medium inside. Here, we present a concise introduction to such quadratic combs and the physical mechanism that underlies their formation. We mainly review our recent experimental and theoretical work on formation and dynamics of quadratic frequency combs. We experimentally demonstrated comb generation in two configurations: a cavity for second harmonic generation, where combs are generated both around the pump frequency and its second harmonic and a degenerate optical parametric oscillator, where combs are generated around the pump frequency and its subharmonic. The experiments have been supported by a thorough theoretical analysis, aimed at modelling the dynamics of quadratic combs, both in frequency and time domains, providing useful insights into the physics of this new class of optical frequency comb synthesizers. Quadratic combs establish a new class of efficient frequency comb synthesizers, with unique features, which could enable straightforward access to new spectral regions and stimulate novel applications.

Journal/Review: MICROMACHINES

Volume: 11 (2)      Pages from: 230-1  to: 230-22

KeyWords: optical frequency combs; quadratic nonlinearity; second harmonic generation; optical parametric oscillator; modulation instability
DOI: 10.3390/mi11020230