THz photonic-crystal lasers with boundary-conditions control

We demonstrate single-mode, surface-emitting terahertz lasers at lambdaap110 mum employing photonic-crystal resonators. The devices employ metal-metal waveguides, and the photonic-crystal lattice is implemented by the sole patterning of the top metal contact, without deep-etching the semiconductor into the photonic crystal holes. The device emission wavelength correctly tunes with the photonic crystal characteristics. In addition, we elucidate the role of the boundary conditions of the photonic-crystal resonator. By removing or not the thick doped semiconductor contact layers after processing, we are able to select the lasing mode of the devices.