Mid-infrared rainbow light-emitting diodes

We demonstrate a room-temperature all-epitaxial guided-mode resonance light-emitting diode operating in the mid-wave infrared. The device comprises a dielectric waveguide with an AlGaAsSb p − i − n diode core, below a layer of grating-patterned GaSb and above a highly doped, and thus, low index, InAsSb layer. Light emitted from the device active region into propagating modes in the waveguide scatters into free space via the GaSb grating, giving rise to spectrally narrow features that shift with emission angle across much of the mid-wave infrared. For collection angles approaching 0 °, we are able to obtain linewidths of ∼2.4 meV across the spectral/angular emission of the LED, corresponding to λ / Δ λ ∼ 570. Fine control of emission wavelength can be achieved by tuning the applied current, which causes a redshift of approximately 20 nm due to the thermo-optic effect. The presented device has the potential for use in compact, high bandwidth, and low-cost mid-wave infrared sensing applications requiring spectral discrimination.