Continuous-wave Lasing in a Solid Polymer

2. Materials, fabrication, and characterization To overcome the insolubility problem of the inorganic precursor salts of rare-earth dopant ions in the polymer host, the Nd 3+ ions were encapsulated in a stable organic complex, Nd(TTA)3phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) (Fig. 1a). The Nd-complex was dissolved into the polymer waveguide material, a solution of 6-FDA/UVR (Fig. 1b). Lifetime quenching by the overtone vibrations of C-H and O-H bonds were diminished by fluorinating the complex and the polymer. The functionalities of active doping and photo-definition were divided over the core and cladding polymers of the waveguide. The low-refractive-index cladding was a cycloaliphatic epoxy prepolymer (Fig. 1c). Channel waveguides of 5  5 μm 2 cross-section and up to several cm length were fabricated by spin-coating the cladding polymer onto a thermally oxidized silicon wafer, photo-defining inverted channel waveguides, back-filling these structures with the Nd-doped core material, and spin coating an upper cladding on top [1]. The measured propagation losses were ~0.10-0.15 dB/cm at 1064 nm. When exciting the Nd 3+ ions near 800 nm, the typical luminescence bands of Nd 3+ were observed (Fig. 2a). Luminescence decay measurements near 1060 nm revealed a lifetime of 141 μs (Fig. 2b) [3].