Demonstration of optical gain at 1.06 μm in a neodymium-doped polyimide waveguide

Neodymium-doped polyimide waveguides were studied for optical amplifier applications. Photoluminescence at 890 nm, 1.06 μm, and 1.33 μm from neodymium ions in the polymer matrix was observed. Optical gain of about 8 dB was measured at 1.06 μm in a 5-cm-long multimode channel waveguide. Phase separation was observed in the doped polyimide. Large scattering losses in the waveguides due to the phase separation were reduced by planarizing the layer of doped polyimide with another layer of undoped polyimide. Such a waveguide amplifier has potential applications in lossless splitters, lossless fiber, and waveguide systems with large fanout.