Hybrid plasmonic-photonic lasing from zinc doped GaAs nanowires

We investigated optically pumped lasing from zinc-doped GaAs nanowires (NWs) on glass and metal films as well as from gold coated NWs. NWs on glass with a diameter of 250 nm and an 8 nm Al₂O₃ coating showed photonic lasing at 80 K when the excitation fluence exceeded 53 μJ/cm². NWs with the same diameter on gold or silver exhibited enhanced lasing and a reduced lasing threshold which is attributed to the increased light confinement and gain feedback of hybrid plasmonic-photonic lasing modes. With increasing temperature, we observe a red-shift and weakening of the laser emission due to band-gap shrinkage and increasing non-radiative losses. While NWs on metal show lasing up to room temperature, NWs on glass stop emitting at ~200 K which is again attributed to the plasmon enhanced light confinement. NWs with diameters of 200 nm and 100 nm diminish the probability for photonic lasing due to increased losses of their sub-wavelength photonic cavity. When put on gold or silver these NWs showed lasing which is predominantly plasmonic. Gold coated NWs show weaker plasmonic lasing because of the reduced transmittance of the exciting laser and the laser emission through the gold film but, the lasing threshold was nearly not affected by the metal coating.