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Unambiguous real-time terahertz frequency metrology using dual 10 GHz femtosecond frequency combs

Kliebisch, Oliver and Heinecke, Dirk C. and Barbieri, Stefano and Santarelli, Giorgio and Li, Hua and Sirtori, Carlo and Dekorsy, Thomas (2018) Unambiguous real-time terahertz frequency metrology using dual 10 GHz femtosecond frequency combs. Optica, 5 (11), pp. 1431-1437. Optical Society of America. DOI: 10.1364/OPTICA.5.001431 ISSN 2334-2536

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Official URL: http://www.osapublishing.org/optica/abstract.cfm?URI=optica-5-11-1431

Abstract

Terahertz frequency metrology by radio frequency downconversion using femtosecond optical sampling relies on the harmonic factor retrieval between the terahertz frequency and the optical sampling rate. At typical femtosecond laser repetition rates, this imposes an ambiguity for frequency metrology. We report on a dual-comb sampling system for the unambiguous frequency measurement of terahertz quantum cascade lasers with hertz-level precision. Two Ti:sapphire oscillators with 10 GHz repetition rate are used for the electro-optic sampling of terahertz radiation at 2.5 THz emitted by actively mode-locked terahertz quantum cascade lasers with 9.7 GHz and 19.6 GHz repetition rates. By coherent downconversion, the emitted terahertz waveforms are measured in the radio frequency domain. The terahertz frequency comb is stabilized by employing a phase-locked loop on a radio frequency beat-note signal. A second infrared sampling comb is used to measure the absolute frequencies of the terahertz radiation. This method, which is based on the detuning of the sampling repetition rates, allows the direct retrieval of the quantum cascade laser's absolute frequency in real time without using additional optical frequency references for calibration. In order to demonstrate the feasibility of the stabilization and readout technique, a high-resolution spectroscopy measurement on gaseous methanol is presented.

Item URL in elib:https://elib.dlr.de/122797/
Document Type:Article
Title:Unambiguous real-time terahertz frequency metrology using dual 10 GHz femtosecond frequency combs
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Kliebisch, Oliveroliver.kliebisch (at) dlr.dehttps://orcid.org/0000-0003-0817-8914
Heinecke, Dirk C.UNSPECIFIEDhttps://orcid.org/0000-0001-7894-3066
Barbieri, StefanoUNSPECIFIEDUNSPECIFIED
Santarelli, GiorgioUNSPECIFIEDhttps://orcid.org/0000-0003-2219-2632
Li, HuaUNSPECIFIEDUNSPECIFIED
Sirtori, CarloUNSPECIFIEDUNSPECIFIED
Dekorsy, ThomasThomas.Dekorsy (at) dlr.dehttps://orcid.org/0000-0003-2257-2854
Date:7 November 2018
Journal or Publication Title:Optica
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:5
DOI :10.1364/OPTICA.5.001431
Page Range:pp. 1431-1437
Publisher:Optical Society of America
ISSN:2334-2536
Status:Published
Keywords:Quantenkaskadenlaser, Femtosekundenlaser, Hochrepetitionsratenlaser, Titan:Saphir-Laser, THz-Strahlung, Spektroskopie, Frequenzmetrologie
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Laser Research and Technology
Location: Stuttgart
Institutes and Institutions:Institute of Technical Physics > Solid State Lasers and Nonlinear Optics
Deposited By: Kliebisch, Oliver
Deposited On:12 Nov 2018 10:26
Last Modified:12 Nov 2018 10:26

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