We present a single-mode, single-polarization, distributed-feedback liquid dye laser, based on a short high-order Bragg grating defined in a single polymer layer between two glass substrates. In this device we obtain single-mode operation in a multimode structure by means of transverse-mode discrimination with antiguiding segments. The laser is fabricated using microfabrication technology, is pumped by a pulsed frequency-doubled Nd:YAG laser, and emits narrow-line-width light in the chip plane at 577 nm. The output from the laser is coupled into integrated planar waveguides defined in the same polymer film. The laser device is thus well suited for integration, for example, into polymer based lab-on-a-chip microsystems.