Attenuation and Bending Measurements of Printed Silicone Waveguides

The attenuation and bending measurements were conducted on multimode silicone waveguides fabricated using an embedded printing process. The process employed EI-1184 (Dow Corning) as the optical silicone material and ETD 2020 (Lubrizol Carbopol®) as the rheologically tuned support matrix.

Printing process and parameters:
The waveguides were produced on a embedded printing system using a conventional Viscotec vipro-HEAD 3 print-head and a Snapmaker 2.0 A350 kinematic. The matrix material concentration was set to 0.3 wt% Carbopol ETD 2020 with a pH modifier Triethanolamin of 40 µL per 100g of distilled water. Printing was performed at a feed rate of 10 mm/s and a printing depth of 10 mm. Waveguides with a diameter of 1.19 mm were printed, corresponding to the inner diameter of the extrusion needle used during printing.

Sample set:
A total of 20 straight waveguides were printed for the attenuation study.

Measurement setup:
Attenuation was determined using cut-back measurements at wavelengths of 405 nm and 625 nm, with cut-back lengths from 8 cm → 6 cm → 5 cm. The light was coupled into the waveguide using a Thorlabs M405FP1 LED (405nm, 24.3 mW) and a M625F2 LED (625nm, 17.5 mW) via a 400 µm SMA fiber. Output was collected through a Thorlabs FP1500ERT fiber (1.5 mm) and measured using a Thorlabs S140C integrating sphere photodiode over a spectral range of 350–1100 nm.

Bending measurements:
For bending-induced attenuation, waveguides were mounted in a V-groove and deformed on a rotational stage adjustable to 0.2° precision. The attenuation was measured over angles from 0–50°.

Results summary:

Straight-waveguide attenuation:
405 nm: α = 0.96 ± 0.02 dB/cm
625 nm: α = 0.81 ± 0.02 dB/cm

Bending attenuation: 0.02 dB/° (0–30° range)

Data coverage:
The dataset contains raw intensity and transmission values for each waveguide, cut-back segment, and bending angle, enabling calculation of attenuation coefficients as a function of wavelength and deformation.