Fabrication of three-dimensional microstructure in optical-gain medium using two-photon-induced photopolymerization technique Shiyoshi Yokoyamaa,b.*, Tatsuo Nakahamaa, Hideki Mikia, Shinro Mashikoa An approach using a laser-dye-doped dendrimer as a two-photon-induced photocurable resin was demonstrated for the fabrication of a three-dimensional microstructure. A dendrimer can encapsulate laser-dye and, as a result, increases its concentration up to 4 wt.% with limted energy transfer during the photopolymerrization process. Confocal microscopic images showed a polymerized structure with a precise control of dimensions and spatial resolution within a submicrometer-scale. We fabricated a polymeric solid-state microcavity, Which consisted of integrated strips arranged in a layer-by-layer structure. The microcavity had a periodic variation in the refractive index, which gave rise to Bragg reflection for laser feedback. Laser emission with a spectral linewidth of 0.15 nm was measured in the microcavity under optical excitation. This laser emission is attributed both to the distributed Bragg reflection and to the high gain of a polymeric medium containing a high concentration of laser-dye.