Thin Film Polymers for Integrated Electro-Optic Devices
Anthony Holland, Darren Simon, Heyshan Mandis, Arnan Mitchell
RMIT University
Australia
Keywords: polymer, waveguide, etching
Integrated electro-optic devices, such as high speed optical modulators, have become key building blocks of broadband communications networks and photonic signal processing systems. Traditionally, these devices have been made from specialised electro-optic substrate materials, such as LiNbO3 requiring complex packaging procedures to provide an electronic interface. This in turn has resulted in the cost of these devices remaining high, inhibiting their mass deployment.
Electro-optic polymer materials have recently been introduced and it is anticipated that these materials may become the material of choice for next generation electro-optic devices. The main advantage of polymers over conventional electro-optic materials is that they can be monolithically integrated with silicon technology by simply spin depositing layers of polymer on silicon integrated circuitry.
In this paper we present progress on the development of integrated electro-optic devices using polymer materials. An essential requirement for photonic waveguide devices is the realisation of thin, transparent films of precise thickness of the order of 1micron that are extremely flat and smooth (roughness of the order of 10Å) to minimise optical scattering. It is also important to be able to pattern these films with ridges to guide the light. These ridges must also be extremely smooth and very precise.
An investigation of the optimum conditions to produce thin photonic quality polymer films with precise control of thickness is presented. Several methods for minimising the resulting surface roughness are also explored.
In addition, a study of the Ion Beam Etching of rib patterns in several photonic polymers is presented. The ion beam conditions investigated include (i) the ionised gas (ii) the angle of the ion beam (iii) ion beam energy and (iv) etching rate. The polymers are masked for etching using ultra-violet photolithographic techniques as used in the silicon industry. The suitability of this technique for patterning polymers is also investigated.