arXiv subjects

Oliver Pitz

Publications and source records attributed to Oliver Pitz.

3 recordsLinked to original sources

arXiv2026

A NICE (Nulling Interferometry Cryogenic Experiment) update: Beyond 1e-5 and towards cryogenic operation

The Nulling Interferometry Cryogenic Experiment (NICE) is a mid-infrared laboratory testbed at ETH Z\"urich that aims to not only reproduce the deep ($<1\times10^{-5}$) broadband nulls of the nulling testbeds of the early 2000s, but also at the required sensitivity levels expected for the LIFE space mission. This sensitivity enforces the experiment to go cryogenic at temperatures around 15 K; an ambitious task for an ultra-precise interferometer. We share our results of the ambient precursor experiment, demonstrating repeatable $<1\times10^{-5}$ nulls at a single wavelength and high throughput, and investigations into the nulling performance across a broader bandpass and with dual polarisation states. We will also highlight the push towards cryogenic operation, with the instalment of a new 15 K test cryostat that will inform our choices of materials and optomechanical mounting techniques.

astro-ph.IM↗

arXiv2026

Integrated tunable mid-infrared electro-optic frequency comb generator based on nonlinear conversion

Mid-infrared frequency combs enable highly selective and sensitive molecular spectroscopy by leveraging the strong vibrational transitions in this spectral region. Among these, there is a particular need for compact, tunable sources with electronic control over comb parameters for integrated sensing platforms. In this work, we demonstrate a mid-infrared electro-optic frequency comb source based on nonlinear frequency conversion in thin film lithium niobate. The system combines a near-infrared pump, amplitude-modulated using an integrated Mach-Zehnder modulator for lock-in detection, with a telecom-band electro-optic comb generated via a double-pass phase modulation scheme. Mid-infrared comb generation is achieved through difference frequency generation in a periodically poled waveguide. By tuning the telecom seed laser and the chip temperature, we obtain mid-infrared combs with a bandwidth of approximately 6 nm and center wavelength tunability of over 200 nm. The comb free spectral range is directly controlled via the applied radio-frequency modulation. Operation across multiple integrated photonic circuits reaching wavelengths up to 3.7 $\mu$m is demonstrated. Furthermore, dual-tone EO comb generation in the mid-infrared is realized. To our knowledge, this is the first integrated mid-infrared electro-optic comb source offering independent electronic control of both center wavelength and comb spacing.

physics.optics↗

arXiv2025

Integrated thin film lithium niobate mid-infrared modulator

The mid-infrared spectral range holds great promise for applications such as molecular spectroscopy and telecommunications. Many key molecules exhibit strong absorption features in this range, and free-space optical communication benefits from reduced atmospheric attenuation and low transmission losses in specific wavelength bands spanning from 3 to 14 $\mu m$. Recent progress in MIR photonics has been fuelled by the rapid development of efficient light sources and detectors. However, further advancement is hindered by the lack of low-loss, high-performance integrated photonic platforms and modulators. Lithium niobate on sapphire is a promising candidate, operating across a broad spectral range from 0.4 $\mu m$ to 4.5 $\mu m$. We demonstrate a broadband, high-speed lithium niobate on sapphire Mach-Zehnder electro-optic modulator operating from 3.95 to 4.3 $\mu m$. The device achieves a 3 dB bandwidth exceeding 20 GHz, an extinction ratio of 34 dB, and a half-wave voltage of 22 V$\cdot$cm, delivering optical output power at the half-milliwatt level. These properties are leveraged to demonstrate data transmission at 10 Gbit/s. The modulator is also used to generate a frequency comb with a width of 80 GHz. Furthermore, we demonstrate full $\pi$-phase modulation in the MIR, representing a key milestone for integrated MIR photonics. These results establish a pathway toward high-speed, energy-efficient MIR photonic systems for applications in telecommunications, sensing, and quantum technologies.

physics.optics↗