Low-cost planar lightwave circuits based on optical polymer waveguide devices hold promise for the next generation of optical communication systems. Over the years, we have put significant effort to exploring the many unique properties of polymer for the realization of new functional optical devices. For example, we have demonstrated several basic polarization-insensitive waveguide devices, where the stress and geometry effects in polymer thin films are balanced through careful waveguide design and thermal tuning. Using a long-period waveguide grating as the basic structure, we have developed a range of broadband filters and add/drop multiplexers, where the large thermooptic coefficient of polymer together with the high temperature sensitivity of the grating design allows an exceedingly wide wavelength range to be tuned thermally. Using vertical optical couplers as building blocks, we have successfully fabricated compact polarization splitters, optical switches, dynamic power splitters, etc. Our other demonstrated devices include waveguide junction splitters and optical interleavers. Recently, we have proposed a new bottom-heating approach for the realization of thermooptic waveguide devices, which can minimize the possibility of damaging the polymer waveguide due to electrode deposition and facilitate electric wiring and device packaging. This paper presents a review of these research activities. © 2010 Copyright SPIE - The International Society for Optical Engineering.