Low-loss fiber-to-chip couplers with ultrawide optical bandwidth

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. © 2019 Author(s)

Efficient Coupling Interfaces in Photonic Systems Enabled by Printed Freeform Micro-Optics

In this presentation, we give an overview of our recent progress in exploiting direct-write two-photon lithography for additive 3D fabrication of freeform micro-optical elements. These elements can be printed with highest precision in direct contact with the facets of photonic integrated circuits or optical fibers, thereby greatly simplifying alignment and improving coupling efficiency. The approach offers new perspectives for a wide variety of applications, ranging from advanced photonic multi-chip modules for high-speed communications and optical sensing to highly efficient astro-photonic systems. We are currently working on transferring the concept from laboratory demonstrations to industrial manufacturing