Printed freeform lens arrays on multi-core fibers for highly efficient coupling in astrophotonic systems

Abstract

Coupling of light into multi-core fibers (MCF) for spatially resolved spectroscopy is of great importance to astronomical instrumentation. To achieve high coupling efficiencies along with fill-fractions close to unity, micro-optical elements are required to concentrate the incoming light to the individual cores of the MCF. In this paper we demonstrate facet-attached lens arrays (LA) fabricated by two-photon polymerization. The LA provide close to 100% fill-fraction along with efficiencies of up to 73% (down to 1.4 dB loss) for coupling of light from free space into an MCF core. We show the viability of the concept for astrophotonic applications by integrating an MCF-LA assembly in an adaptive-optics test bed and by assessing its performance as a tip/tilt sensor.

Ultra-long-working-distance spectroscopy of single nanostructures with aspherical solid immersion microlenses

“…µ-lenses were produced with two-photon 3D photolithography (DLW), which has been proven to yield highquality optical elements of arbitrary shape for lab-on-chip and optical fibre applications [26][27][28][29][30] . Figure 2a shows a scanning electron microscope (SEM) image of an elliptical µ-lens with a diameter of 15 µm.…”

Fiber‐Optic SERS Probes Fabricated Using Two‐Photon Polymerization For Rapid Detection of Bacteria

“…Moreover, the 2PP technique is well suited to small‐scale substrates, which is beneficial when applied to optical fiber end‐facets 23. Thus, fabrication of sophisticated structures on optical fiber tips has been successfully demonstrated using 2PP, with examples including micro‐optics,24–27 a miniature acoustic sensor,28 a microscale force sensor,29 and a force‐sensitive micro‐grasping tool 30. In the field of SERS, 2PP has been utilized to build polymeric templates, supports, or masks for lift‐off processes of metal layers, but these were mainly based on wafer‐scale substrates 31–36.…”

Photonic Wire Bonding and 3D Nanoprinting in Photonic Integration – from Lab Demonstrations to Production

“…We demonstrated the viability of the concept by realizing multi-chip transmitter modules that combine silicon photonic modulators with InPbased laser-sources in highly integrated assemblies [6], [7]. Using the same lithography techniques, we have shown high-precision in-situ printing of lenses to facets of photonic chips and optical fibers [8] - [10]. This approach does not only allow for low-loss coupling of PIC to free-space beams in a wide variety of optical assemblies, but also opens novel opportunities in other areas such as astrophotonics, where efficient coupling between free-space beams and optical fibers is essential [10].…”

“…Using the same lithography techniques, we have shown high-precision in-situ printing of lenses to facets of photonic chips and optical fibers [8] - [10]. This approach does not only allow for low-loss coupling of PIC to free-space beams in a wide variety of optical assemblies, but also opens novel opportunities in other areas such as astrophotonics, where efficient coupling between free-space beams and optical fibers is essential [10]. Taking a longterm view, on-chip 3D freeform waveguides [11] might allow large-scale non-planar circuit topologies that are, e. g., at the heart of advanced optical switches.…”