The applicability of a polyamide-imide (PAI) polymer to thin film optical applications was investigated. The polymer preparation and spin characteristics are described in detail. The films exhibited good adhesion to silicon, glass, and benzocyclobutene polymer. The refractive index was measured in the near infrared region. To demonstrate feasibility for devices, features were plasma etched into PAI films. Oversized inverted rib waveguides were also fabricated using PAI as a core material, and losses as low as 0.2 dB/cm were measured at 830 nm. Polyamide-imide is a highly robust and stable polymer, similar to the widely used polyimides, and is an excellent candidate material for integrated optics applications. (C) 2003 Elsevier B.V. All rights reserved.