arXiv subjects

Mateusz Narożnik

Publications and source records attributed to Mateusz Narożnik.

4 recordsLinked to original sources

arXiv2025

Broadband birefringence spectroscopy with sub-kHz precision

Although current amorphous high-reflective mirror coatings have had tremendous success in metrology applications, they are inherently limited by thermal fluctuations in their coating structure. Alternatively, crystalline coating technology has demonstrated superior thermal noise performance. However, recent studies have revealed birefringent noise sources, raising questions about the limits of frequency stability of high-finesse cryogenic silicon cavities with crystalline mirror coatings. Here, we show the applicability of cavity-mode dispersion spectroscopy to measure birefringent cavity mode splitting. We measured birefringence induced cavity mode splitting by probing the resonance frequencies of a high-finesse, ultra-low expansion glass cavity with all-crystalline mirror coatings, reaching fractional frequency sensitivity of \SI{5e-14}{} utilizing an optical frequency comb for two orthogonal polarizations. Subsequently, we calculated the static birefringent splitting of the refractive index for \SI{23.8}{\celsius} and \SI{31.3}{\celsius} on the order of \SI{305 \pm 3}{ppm} and \SI{294 \pm 3}{ppm} over \SI{30}{nm} respectively. Furthermore, we propose measurements of dispersive birefringent noise based on optical frequency combs. Our results not only extend the use of optical frequency combs to measure static birefringence, but also implicate a possibility to further study spectrally dependent frequency noise.

physics.optics↗

arXiv2025

Mechanical loss and stability analysis of NEXCERA in ultra-stable optical cavities

NEXCERA has emerged as a ceramic-based material for spacers in ultra-stable optical cavities, with a coefficient of thermal expansion that crosses zero near room temperature. In such cavities, frequency stability is ultimately limited by Brownian thermal noise in the cavity components. A key parameter in this context is the mechanical loss, which has remained unknown for NEXCERA. In this work, we investigate the mechanical loss of NEXCERA N117B at room temperature for various resonances using the gentle nodal suspension technique. We measure a promising minimum mechanical loss of $ϕ= 1.89\times 10^{-5}$, indicating the suitability of NEXCERA for low-noise optical cavities. Using this value, we calculate the thermal noise of a cavity with a NEXCERA spacer and compare its performance to established materials such as ULE and Zerodur, taking into account different mirror substrate options. Our analysis shows that NEXCERA is a strong candidate for ultra-stable cavities due to its low thermal noise. Combined with its previously reported low linear drift, it offers a highly attractive option for long-term stable optical frequency references.

physics.optics↗

arXiv2025

Guidelines for designs for ultrastable laser with $\mathbf{10^{-17}}$ fractional frequency instability

Lasers with long coherence time and narrow linewidth are an essential tool for quantum sensors and clocks. Ultrastable cavities and laser systems are now commercially available with fractional frequency instabilities in the mid $10^{-16}$ range. This document aims to provide technical guidance for researchers starting in the field of ultrastable lasers and to give an outlook toward the next generation of improved ultrastable lasers. These guidelines have arisen from the scope of the EMPIR project ``Next generation ultrastable lasers'' ( https://www.ptb.de/empir2021/nextlasers ) with contributions from the European project partners.

physics.optics↗

arXiv2025

Cavity-enhanced spectroscopy in the deep cryogenic regime -- new hydrogen technologies for quantum sensing

Spectrometers based on high-finesse optical cavities have proven to be powerful tools for applied and fundamental studies. Extending this technology to the deep cryogenic regime is beneficial in many ways: Doppler broadening is reduced, peak absorption is enhanced, the Boltzmann distribution of rotational states is narrowed, all unwanted molecular species disturbing the spectra are frozen out, and dense spectra of complex polyatomic molecules become easier to assign. We demonstrate a cavity-enhanced spectrometer fully operating in the deep cryogenic regime down to 4 K. We solved several technological challenges that allowed us to uniformly cool not only the sample but also the entire cavity, including the mirrors and cavity length actuator, which ensures the thermodynamic equilibrium of a gas sample. Our technology well isolates the cavity from external noise and cryocooler vibrations. This instrument enables a variety of fundamental and practical applications. We demonstrate a few examples based on accurate spectroscopy of cryogenic hydrogen molecules: accurate test of the quantum electrodynamics for molecules; realization of the primary SI standards for temperature, concentration and pressure in the deep cryogenic regime; measurement of the H$_{2}$ phase diagram; and determination of the ortho-para spin isomer conversion rate.

physics.atom-ph↗