An external-cavity laser, suitable for producing a coherent and highly-polarized optical emission, particularly at communication wavelengths, is enabled by a novel wavelength selective element based on a waveguide technology that supports a long-range plasmons polariton mode. These external-cavity lasers leverage the inherent properties of the novel wavelength selective elements, which are materials agnostic, providing easier means for tunability, laser stability, and low cost of fabrication, high output power and a highly polarized output. Tunable versions are also disclosed.