Opt. Express 19, 15109–15118 (2011)

Most nanolasers demonstrated so far have exploited optical pumping at cryogenic temperatures, owing to problems with increased heating when using electrical pumping. Milan Marell and colleagues from Technische Universiteit Eindhoven in the Netherlands have now demonstrated electrically pumped room-temperature lasing at telecommunications wavelengths from gap–plasmon structures in semiconductor samples. The resulting device can be continuously driven at low temperatures of 80 K, producing a sharp spectral line. The device output has a strong transverse-magnetic polarization — as expected for a gap–plasmon mode — and a threshold current of around 500 μA. At room temperature, the researchers observed pulsed lasing for a pulsed voltage source with a repetition rate of 1 MHz and a pulse width of 50 ns. They formed gap–plasmon waveguides from a silver cladding covering an SiN insulator layer and an InGaAs gain region. They achieved distributed feedback by periodically varying the waveguide width to create a grating, and then changed the grating parameters to vary the lasing wavelength in the range of ∼1,450–1,500 nm.