Low-loss fiber-to-chip couplers with ultrawide optical bandwidth
H. Gehring,
M. Blaicher,
W. Hartmann,
P. Varytis,
K. Busch,
M. Wegener,
W. H. P. Pernice
Affiliations
H. Gehring
Institute of Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
M. Blaicher
Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
W. Hartmann
Institute of Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
P. Varytis
Humboldt-Universität zu Berlin, Institut für Physik, AG Theoretische Optik & Photonik, Newtonstr. 15, 12489 Berlin, Germany
K. Busch
Humboldt-Universität zu Berlin, Institut für Physik, AG Theoretische Optik & Photonik, Newtonstr. 15, 12489 Berlin, Germany
M. Wegener
Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany
W. H. P. Pernice
Institute of Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
Providing efficient access from optical fibers to on-chip photonic systems is a key challenge for integrated optics. In general, current solutions allow either narrowband out-of-plane-coupling to a large number of devices or broadband edge-coupling to a limited number of devices. Here we present a hybrid approach using 3D direct laser writing, merging the advantages of both concepts and enabling broadband and low-loss coupling to waveguide devices from the top. In the telecom wavelength regime, we demonstrate a coupling loss of less than −1.8 dB between 1480 nm and 1620 nm. In the wavelength range between 730 nm and 1700 nm, we achieve coupling efficiency well above −8 dB which is sufficient for a range of broadband applications spanning more than an octave. The 3D couplers allow relaxed mechanical alignment with respect to optical fibers, with −1 dB alignment tolerance of about 5 µm in x- and y-directions and −1 dB alignment tolerance in the z-direction of 34 µm. Using automatized alignment, many such couplers can be connected to integrated photonic circuits for rapid prototyping and hybrid integration.
