Fabrication of fluorinated polyimide optical waveguides by micropen direct writing technology

A novel and cheap direct writing method based on the micropen has been developed to fabricate fluorinated polyimide stripe optical waveguides on Si/SiO2 wafers. The overall design, starting material, micropen direct writing system and fabrication processes of the stripe optical waveguides are presented. The effects of the key direct writing parameters, such as the tip-to-substrate distance, extrusive gas pressure, writing speed and viscosity of the polyamic acid, on the dimension and morphology of the stripe optical waveguides are discussed in detail. After deposition by the micropen system and baking process, the fluorinated polyimide stripe optical waveguides with good morphology and surface quality can be fabricated using the optimal parameters. The propagation losses at the wavelength of 1.55 μm are in the range of 1.4–3.5 dB cm−1 as characterized by different length combinations of the strip optical waveguides.

Research highlights
► Deposit fluorinated polyimide stripe optical waveguides on Si/SiO2 wafers using the direct writing method based on a designed micropen.
► Key direct writing parameters, such as tip-to-substrate distance, extrusive gas pressure, writing speed and viscosity of the polyamic acid, have been investigated to control the dimension and morphology of the stripe optical waveguides.
► Stripe optical waveguides with good morphology, surface quality and low losses can be fabricated cheaply and easily at the optimal parameters.
► Except for the simple stripe optical waveguides, optoelectronic devices with complex patterns are promising to be directly fabricated at low cost using this method only or by combining with other micro-manufacturing methods in the future.