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The performance of fiber-fed astronomical spectrographs is highly influenced by the properties of fibers. The near-field and far-field scrambling characteristics have a profound impact on the line spread function (LSF) of the spectra. Focal…
Optical fibres are essential for many types of highly-multiplexed and precision spectroscopy. The success of the new generation of multifibre instruments under construction to investigate fundamental problems in cosmology, such as the…
Optical fibers are a key component for high-resolution spectrographs to attain high precision in radial velocity measurements. We present a custom fiber with a novel core geometry - a 'D'-shape. From a theoretical standpoint, such a fiber…
Modal noise is a common source of noise introduced to the measurements by optical fibres and is particularly important for fibre-fed spectroscopic instruments, especially for high-resolution measurements. This noise source can limit the…
The performance of highly-multiplexed spectrographs is limited by focal degradation (FRD) in the optical fibres. It has already been shown that this is caused mainly by processes concentrated around the mounting points at the ends of the…
We report on extensive testing carried out on the optical fibers for the VIRUS instrument. The primary result of this work explores how 10+ years of simulated wear on a VIRUS fiber bundle affects both transmission and focal ratio…
Starting from our puzzling on-sky experience with the GIANO-TNG spectrometer we set up an infrared high resolution spectrometer in our laboratory and used this instrument to characterize the modal noise generated in fibers of different…
We present measurements of how multimode fiber focal-ratio degradation (FRD) and throughput vary with levels of fiber surface polish from 60 to 0.5 micron grit. Measurements used full-beam and laser injection methods at wavelengths between…
Fiber-fed etalons are widely employed in advanced interferometric instruments such as gravitational-wave detectors, ultrastable lasers and calibration reference for high-precision spectrographs. We demonstrate that variation in near-field…
We report a simple and efficient all-optical polarization scrambler based on the nonlinear interaction in an optical fiber between a signal beam and its backward replica which is generated and amplified by a reflective loop. When the…
Modal noise in fibers has been shown to limit the signal-to-noise ratio achievable in fiber-coupled, high-resolution spectrographs if it is not mitigated via modal scrambling techniques. Modal noise become significantly more important as…
We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index $n$$\sim$2 ball lens that exchanges the near…
We are now moving into an era where multi-object wide-field surveys, which traditionally use single fibres to observe many targets simultaneously, can exploit compact integral field units in place of single fibres. Current multi-object…
For fiber-fed spectrographs with a stable external wavelength source, scrambling properties of optical fibers and, homogeneity and stability of the instrument illumination are important for the accuracy of radial-velocimetry. Optical…
Focal Ration Degradation (FRD) is a change in light angular distribution caused by fiber optics. FRD is important to fiber-fed, spectroscopic astronomical systems because it can cause loss of signal, degradation in spectral resolution, or…
Fiber modal noise is a performance limiting factor in high-precision radial velocity measurements with multi-mode fiber-fed high-resolution spectrographs. Traditionally, modal noise is mitigated by agitating the fiber, this way…
Fiber modal noise is a performance limiting factor in high-resolution spectroscopy, both with respect to achieving high signal-to-noise ratios or when targeting high-precision radial velocity measurements, with multi-mode fiber-fed…
We have built and commissioned a prototype agitated non-circular core fiber scrambler for precision spectroscopic radial velocity measurements in the near-infrared H band. We have collected the first on-sky performance and modal noise tests…
Hollow-core anti-resonant fibers (HC-ARFs) have earned great attention in the fiber optics community due to their remarkable light-guiding properties and broad application spectrum. Particularly nested HC-ARFs have recently reached…
In an ideal perfectly straight multimode fiber with a circular-core, the symmetry ensures that rotating the input wavefront leads to a corresponding rotation of the output wavefront. This invariant property, known as the rotational memory…