Prof. Dr. Oliver Gerberding

@article{c7b00b8005af451ba3fba792ab4b5dd4,

title = "Tunable Coherence Laser Interferometry: Demonstrating 40 dB of Stray Light Suppression and Compatibility with Resonant Optical Cavities",

abstract = "A major limitation of laser interferometers using continuous wave lasers are parasitic light fields, such as ghost beams, scattered or stray light, that can cause nonlinear noise. This is especially relevant for laser interferometric ground-based gravitational wave detectors. Increasing their sensitivity, particularly at frequencies below 10 Hz, is threatened by the influence of parasitic photons. These can up-convert low-frequency disturbances into phase and amplitude noise inside the relevant measurement band. By artificially tuning the coherence of the lasers, using pseudo-random-noise (PRN) phase modulations, this influence of parasitic fields can be suppressed. As it relies on these fields traveling different paths, it does not sacrifice the coherence for the intentional interference. We demonstrate the feasibility of this technique experimentally, achieving noise suppression levels of 40 dB in a Michelson interferometer with an artificial coherence length below 30 cm. We probe how the suppression depends on the delay mismatch and length of the PRN sequence. We also prove that optical resonators can be operated in the presence of PRN modulation by measuring the behavior of a linear cavity with and without such a modulation. By matching the resonators round-trip length and the PRN sequence repetition length, the classic response is recovered. ",

keywords = "Atomic, Molecular, and Optical Physics, Optics, Instrumentation and Methods for Astrophysics, General Relativity and Quantum Cosmology, Instrumentation and Detectors",

author = "Daniel Voigt and Leonie Eggers and Katharina-Sophie Isleif and Koehlenbeck, \{Sina M.\} and Melanie Ast and Oliver Gerberding",

year = "2025",

month = may,

day = "28",

doi = "10.1103/PhysRevLett.134.213802",

language = "English",

volume = "134",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "21",

@article{e094431d12174391a11d0cf271d80b75,

title = "Seismic Noise Contributions to EuXFEL Bunch Arrival Time Jitter from Ocean-Generated Microseism",

abstract = "Measurements of the bunch arrival times at the European XFEL show noise contributions in the spectral range between 0.05 Hz and 0.5 Hz with peak-to-peak jitter of up to 25 fs. Correlation with Distributed Acoustic Sensing (DAS) measurements confirms the seismic origin. The seismic noise in this frequency band is known to be ocean-generated microseism. Both primary and secondary ocean-generated microseism were identified using seismometers and a numerical ocean wave model. Whereas secondary microseism has a strong impact on the bunch arrival time, primary microseism has no notable effect. Rayleigh waves cause the effect, while Love waves have minimal impact. In the presented cases, the noise originates from the North Atlantic and/or the North Sea. The amplitude of the noise depends on the local weather conditions and is much stronger in winter. Ocean-generated microseism is a significant bottleneck that must be addressed to achieve femtosecond bunch arrival time stability in the sub-Hz regime.",

keywords = "Distributed Acoustic Sensing, European XFEL, large-scale FEL, microseism, stability",

author = "Erik Genthe and Czwalinna, \{Marie Kristin\} and Bj{\"o}rn Lautenschlager and Holger Schlarb and Celine Hadziioannou and Oliver Gerberding and Katharina-Sophie Isleif",

year = "2025",

month = apr,

day = "25",

doi = "10.1017/hpl.2025.40",

language = "English",

journal = "High Power Laser Science and Engineering",

issn = "2052-3289",

publisher = "Cambridge University Press",

@article{947b8f54c37444d3b0a4583f5881d333,

title = "Integrating high-precision and fringe-scale displacement sensing using heterodyne cavity-tracking",

abstract = "We present a heterodyne stabilized cavity-based interferometer scheme that can serve as a compact and high-sensitivity displacement sensor with a fringe-scale operating range. The technique, in principle, can reach a sub-femtometer noise floor and an operating range on the order of one laser wavelength at λ ≈ 1 μm. With our current experimental setup, we achieve a sensitivity of about 260 Hz at 1 Hz and 46 Hz at around 130 Hz. By probing a length actuated cavity, we demonstrate six orders of magnitude of dynamic range for displacement measurement, reaching a maximum motion of 0.15 μm. The tracking bandwidth and displacement range are limited by analog effects in the signal digitization and are extendable in the future.",

author = "\{Chalathadka Subrahmanya\}, Shreevathsa and Darsow-Fromm, \{Christian Domenic\} and Oliver Gerberding",

year = "2025",

month = jan,

day = "28",

doi = "10.1364/OE.540189",

language = "English",

volume = "33",

pages = "4044--4054",

journal = "Optics express",

issn = "1094-4087",

publisher = "The Optical Society",

number = "3",

@article{2db530ffc8104b7584794b354ab3813b,

title = "The Lunar Gravitational-wave Antenna: Mission Studies and Science Case",

abstract = "The Lunar Gravitational-wave Antenna (LGWA) is a proposed array of next-generation inertial sensors to monitor the response of the Moon to gravitational waves (GWs). Given the size of the Moon and the expected noise produced by the lunar seismic background, the LGWA would be able to observe GWs from about 1 mHz to 1 Hz. This would make the LGWA the missing link between space-borne detectors like LISA with peak sensitivities around a few millihertz and proposed future terrestrial detectors like Einstein Telescope or Cosmic Explorer. In this article, we provide a first comprehensive analysis of the LGWA science case including its multi-messenger aspects and lunar science with LGWA data. We also describe the scientific analyses of the Moon required to plan the LGWA mission. ",

keywords = "General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics",

author = "Parameswaran Ajith and \{Amaro Seoane\}, Pau and \{Arca Sedda\}, Manuel and Riccardo Arcodia and Francesca Badaracco and Enis Belgacem and Stefano Benetti and Alexey Bobrick and Alessandro Bonforte and Elisa Bortolas and Valentina Braito and Marica Branchesi and Adam Burrows and Enrico Cappellaro and \{Della Ceca\}, Roberto and Chandrachur Chakraborty and \{Chalathadka Subrahmanya\}, Shreevathsa and Coughlin, \{Michael W.\} and Stefano Covino and Andrea Derdzinski and Aayushi Doshi and Maurizio Falanga and Stefano Foffa and Alessia Franchini and Alessandro Frigeri and Yoshifumi Futaana and Oliver Gerberding and Kiranjyot Gill and \{Di Giovanni\}, Matteo and Giudice, \{Ines Francesca\} and Margherita Giustini and Philipp Gl{\"a}ser and Jan Harms and \{van Heijningen\}, Joris and Francesco Iacovelli and Kavanagh, \{Bradley J.\} and Taichi Kawamura and Arun Kenath and Elisabeth-Adelheid Keppler and Chiaki Kobayashi and Goro Komatsu and Valeriya Korol and N.\textasciitilde{}V. Krishnendu and Prayush Kumar and Francesco Longo and Michele Maggiore and Michele Mancarella and Andrea Maselli and Alessandra Mastrobuono-Battisti and Francesco Mazzarini and Andrea Melandri and Daniele Melini and Sabrina Menina and Giovanni Miniutti and Deeshani Mitra and Javier Mor{\'a}n-Fraile and Suvodip Mukherjee and Niccol{\`o} Muttoni and Marco Olivieri and Francesca Onori and \{Alessandra Papa\}, Maria and Ferdinando Patat and Tsvi Piran and Silvia Piranomonte and \{Roper Pol\}, Alberto and Pookkillath, \{Masroor C.\} and R. Prasad and Vaishak Prasad and \{De Rosa\}, Alessandra and Chowdhury, \{Sourav Roy\} and Roberto Serafinelli and Alberto Sesana and Paola Severgnini and Angela Stallone and Jacopo Tissino and Hrvoje Tkal{\v c}i{\'c} and Lina Tomasella and Martina Toscani and David Vartanyan and Cristian Vignali and Lucia Zaccarelli and Morgane Zeoli and Luciano Zuccarello",

year = "2025",

month = jan,

day = "28",

doi = "10.1088/1475-7516/2025/01/108",

language = "English",

volume = "2025",

journal = "Journal of cosmology and astroparticle physics ",

issn = "1475-7516",

publisher = "IOP",

number = "1",

@article{264274a0143948d2bf318589d9ac05df,

title = "On the development of an RFSoC-based ultra-fast Phasemeter with GHz bandwidth",

abstract = "Precise measurements of the frequency and phase of an electrical or optical signal play a key role in various branches of science and engineering. Tracking changing laser frequencies is specifically demanding when the lasers themselves are noisy or if the frequencies rapidly change because they encode highly dynamic signals in, e.g., Doppler-ranging or dynamic cavity readout. Here, we report the development of a high signal bandwidth (> 2 GHz) and high tracking bandwidth (2 MHz) multi-channel Phasemeter. The implementation utilizes an all-digital phase-locked loop realized within the field programmable gate array (FPGA) part of a Radio Frequency System-on-Chip (RFSoC), the programmable logic. We present performance measurements, discuss the role of the high tracking bandwidth for tracking highly dynamic signals, and demonstrate ultra-stable phase locking of a beat note between two widely tunable external cavity diode lasers. We achieve a phase-noise floor in the sub-milli radian regime, even for GHz signals, and demonstrate stable tracking of signals with a frequency change rate of 240 GHz/s. ",

keywords = "Field programmable gate arrays, Frequency measurement, Phase locked loops",

author = "\{Chalathadka Subrahmanya\}, Shreevathsa and Christian Darsow-Fromm and Oliver Gerberding",

year = "2024",

month = dec,

day = "5",

doi = "10.1109/TIM.2024.3509586",

language = "English",

volume = "74",

journal = "IEEE Transactions on Instrumentation and Measurement",

issn = "0018-9456",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

@article{eac924a2fefd4c2f8f68b92f0ee4453b,

title = "An analytic, efficient and optimal readout algorithm for compact interferometers based on deep frequency modulation",

abstract = "Compact laser interferometers with large dynamic range are one of the core emerging tools to improve low frequency performance in gravitational wave detectors by providing local displacement sensing with sub 1 pm Hz-0.5 precision. Strong sinusoidal frequency modulations are used in such laser interferometers to create heterodyne-like photodetector signals from which the phase and other parameters, such as the absolute distance, can be extracted. The nested sinusoidal function in such signals is a challenge for the real-time parameter estimation in low-noise applications. In this article, we present an algorithm to calculate exact signal parameters in a non-iterative way from such interferometric signals. The algorithm makes use of a recurrence relation between Bessel functions to enable a direct extraction of modulation parameters from the signal. Additionally, the algorithm is capable of dealing with high phase dynamics where the Doppler-shift of the signal becomes relevant and can limit the range and precision of the parameter estimation, if not accounted for. Simulations show that the algorithm is computationally efficient, can be well parallelised and the phase estimation is close to optimal precision given by the Cramer–Rao lower bound of the signal parameters.",

author = "Tobias Eckhardt and Oliver Gerberding",

year = "2024",

month = sep,

day = "23",

doi = "10.1038/s41598-024-70392-9",

language = "English",

volume = "14",

journal = "Scientific Reports",

issn = "2045-2322",

publisher = "Springer Nature",

number = "1",