arXiv subjects

Julius Göhring

Publications and source records attributed to Julius Göhring.

3 recordsLinked to original sources

arXiv2026

Demonstration of a multimode-to-multimode photonic lantern for astronomy

Photonic lanterns have been widely used in astronomy as low-loss multiplexing devices, typically coupling light from a multimode input into several single-mode outputs. In this work, we present the first multimode-to-multimode photonic lantern specifically designed to combine light from several multimode fibers into a single multimode waveguide. We fabricated and characterized the devices at multiple wavelengths to evaluate the performance of the adiabatic multimode transition. The measured efficiencies exceed $90\ \%$, demonstrating low-loss multimode propagation and efficient modal transfer through the lantern structure. This architecture enables efficient multimode beam combination and represents a significant step toward scalable modular telescope concepts without requiring diffraction-limited injection.

astro-ph.IM↗

arXiv2026

Comparative analysis of fiber Bragg grating filter losses inscribed by continuous wave UV and femtosecond-IR lasers for astrophotonics

Fiber Bragg grating (FBG) filters have been demonstrated as promising components in astrophotonic instrumentation for near-infrared ground-based observations. Given the photon-starved nature of astronomical applications, it is critical to minimize insertion losses across astrophotonic components. In addition to the insertion loss (IL) introduced by specialty fibers and inscription techniques, FBGs exhibit cladding mode (CM) losses. In this work, we studied the loss characteristics of five filter lines in three photosensitive fibers, i.e., a low-numerical-aperture (NA) fiber, a high-NA bend-insensitive fiber, and a cladding-mode-suppressed (CMS) fiber, and in a non-photosensitive fiber, SMF-28. The filters were inscribed using two phase mask-based illumination methods: a continuous wave ultraviolet (UV) laser with a complex phase mask allowing for multi-channel filters, and a femtosecond infrared (fs-IR) laser with phase mask integrated shaping apertures for spectral profile control. Our results show that UV-inscribed gratings in high-NA bend-insensitive fiber yield the lowest CM losses ($\approx$ 0.5 dB) among photosensitive fibers, but exhibit the highest IL (4.6 dB), and FBGs in non-photosensitive SMF-28 fiber, inscribed with fs-IR, achieve the lowest IL (< 0.05 dB) with a comparatively higher CM loss (0.93 dB). To reduce the high IL in high-NA fiber, we explored tapering and bridging methods and report that bridging reduces IL by $\sim$ 3 dB. We show that both filter platforms remain viable for integration into an astrophotonic system, with IL below 1 dB. Finally, we propose a compact bridge-fiber scheme with the potential to further reduce IL to below 0.5 dB while reducing the number of bridging fibers and, consequently, the number of splice junctions by 50%.

astro-ph.IM↗

arXiv2026

Towards a Comprehensive Understanding of Planetary Systems through Population-Level, Large-Scale Surveys

Over the past three decades, exoplanet research has delivered an extensive census of planets spanning a wide range of masses, sizes, and orbital configurations. Despite this progress, the physical interpretation of these populations remains severely limited, as precise constraints on planetary masses, interior structures, and atmospheres are available only for a small, highly selected subset of targets. As a result, most known exoplanets remain physically ambiguous, preventing the construction of robust population-level trends and limiting our understanding of planet formation, evolution, and habitability. In the coming decades, missions such as PLATO, Earth 2.0, and the Nancy Grace Roman Space Telescope will dramatically expand the number of exoplanets detected. However, without a corresponding capability to characterise planetary masses and atmospheres at scale, these discoveries will remain largely detection-driven. Current and planned facilities, including JWST and ELT-class instruments, excel at detailed studies of individual systems but are intrinsically unsuited for large, homogeneous surveys. This white paper identifies population-level physical characterisation as a fundamental science challenge for the 2040s and motivates the need for a new observational paradigm. We outline how photonics-enabled, modular telescope architectures can deliver the survey speed, stability, and scalability required to jointly probe planetary interiors and atmospheres across statistically meaningful samples, thereby enabling a comprehensive and physically grounded understanding of planetary systems.

astro-ph.IM↗