Frequency-Comb Spectrum of Periodic-Patterned Signals.
Using arbitrary periodic pulse patterns we show the enhancement of specific frequencies in a frequency comb. The envelope of a regular frequency comb originates from equally spaced, identical pulses and mimics the single pulse spectrum. We investigated spectra originating from the periodic emission of pulse trains with gaps and individual pulse heights, which are commonly observed, for example, at high-repetition-rate free electron lasers, high power lasers, and synchrotrons. The ANKA synchrotron light source was filled with defined patterns of short electron bunches generating coherent synchrotron radiation in the terahertz range. We resolved the intensities of the frequency comb around 0.258 THz using the heterodyne mixing spectroscopy with a resolution of down to 1 Hz and provide a comprehensive theoretical description. Adjusting the electron's revolution frequency, a gapless spectrum can be recorded, improving the resolution by up to 7 and 5 orders of magnitude compared to FTIR and recent heterodyne measurements, respectively. The results imply avenues to optimize and increase the signal-to-noise ratio of specific frequencies in the emitted synchrotron radiation spectrum to enable novel ultrahigh resolution spectroscopy and metrology applications from the terahertz to the x-ray region.
Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Johannes L
JL
Steinmann
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Edmund
E
Blomley
Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Miriam
M
Brosi
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Erik
E
Bründermann
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Michele
M
Caselle
Virginia Diodes Inc., Charlottesville, Virginia 22902, USA.
Jeffrey L
JL
Hesler
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Nicole
N
Hiller
Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Benjamin
B
Kehrer
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Yves-Laurent
YL
Mathis
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Michael J
MJ
Nasse
Institute of Micro- und Nanoelectronic Systems, Karlsruhe Institute of Technology, 76187 Karlsruhe, Germany.
Juliane
J
Raasch
Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Manuel
M
Schedler
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Patrik
P
Schönfeldt
Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Marcel
M
Schuh
Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Markus
M
Schwarz
Institute of Micro- und Nanoelectronic Systems, Karlsruhe Institute of Technology, 76187 Karlsruhe, Germany.
Michael
M
Siegel
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Nigel
N
Smale
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Marc
M
Weber
Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.
Anke-Susanne
AS
Müller