Substrate-free miniaturized thin-film filters for single-element coarse wavelength division multiplexing fibers

Abstract

We have created high-precision, miniaturized, substrate-free filters, based on ion beam sputtering on a sacrificial substrate. The sacrificial layer is cost efficient and environmentally friendly and can be dissolved using only water. We demonstrate an improved performance compared to filters on thin polymer layers from the same coating run. With these filters, a single-element coarse wavelength division multiplexing transmitting device for telecommunication applications can be realized by inserting the filter between fiber ends.

Spectrally aligned integration of miniaturized substrate-free thin-film filters for fiber optical networks

“…PVA on Si-wafer IBS: Functional coating Laser segmentation Water bath Substrate-free TFFs Lensing effects generated from the TFF chip itself have not to be considered, since the filter chips are flat across the measurement location when used with small core fibers. 4…”

“…Recent research has demonstrated that substrate-free, miniaturized TFFs are ideal for fabricating single-element coarse wavelength division demultiplexing patch cables for telecommunication channels. 4 Since this type of TFFs can be integrated directly into the fiber connector, it is an extremely compact realization and no other components are needed to achieve the demultiplexing except the functionalized fiber itself. In contrast to this, traditional TFFs typically have substrates measuring hundreds of micrometers, resulting in an expansion of the beam diameter during propagation through these components.…”

Miniaturized thin-film filters to connect multiple self-written waveguides

“…Inside the dielectric filter and the substrate, waveguiding, as it occurs inside the polymerized monomer, is no longer effective and the beam diverges slightly. A miniaturized, substrate-free filter would reduce the crucial propagation length in the transmission direction and thus the beam divergence as well [35]. While a typical glass substrate has a thickness from one to a few millimeters, the substrate-free thin-film is much thinner, of the order of micrometers.…”

“…The filter design was deposited on sacrificial substrates in an ion beam sputtering process [35]. To achieve a high layer thickness accuracy, in situ process control with a high resolution optical broadband monitor was used [37].…”

“…In this work, we present a novel approach, in which a customized miniaturized thin-film filter element [35] was combined with an SWW to stably connect multiple outputs with one input port. Hereby, the flexibility and convenient processability of SWWs are especially advantageous with regard to the realization of optical networks for applications in shortdistance sensing or monitoring where low intensity levels are usually sufficient.…”