Helically bent structure of straight optical waveguide for flexible optical interconnection

We fabricated straight multimode optical waveguide films to analyze quantitatively the effectiveness of the helical bending. The optical waveguide films were very flexible and the refractive index difference between the core and the clad was 1.53% at a wavelength of 0.85 mum. This paper focuses on the helical bending losses under a proper index difference. Therefore, we measured first the bending losses with various bending radiuses and then the helical bending losses with various inclined angles and the radiuses, sequentially. As a result, we could improve the bending loss by 4 dB at 60deg- inclined angle and 1 mm radius, compared to a normal bending structure. In addition, we fabricated a flexible optical interconnection module linked with the flexible optical waveguide to investigate how the helical bending has an effect on data transmission. The optical interconnection module was composed of vertical cavity surface emitting laser, photodiode, and a 45deg-ended waveguide. The helical bending was applied to the waveguide of the optical interconnection module and data transmission characteristics with the inclined angles were measured.