  Thermal radiation from an unpatterned object is similar to that of a gray
body. The thermal emission is insensitive to polarization, shows only
Lambertian angular dependence, and is well modeled as the product of the
blackbody distribution and a scalar emissivity over large frequency bands.
Here, we design, fabricate and experimentally characterize the spectral,
polarization, angular and temperature dependence of a microstructured SiC dual
band thermal infrared source, achieving independent control of the frequency
and polarization of thermal radiation in two spectral bands. The measured
emission of the device in the Reststrahlen band (10.3-12.7 um) selectively
approaches that of a blackbody, peaking at an emissivity of 0.85 at Lx=11.75 um
and 0.81 at Ly=12.25 um. This effect arises due to the thermally excited phonon
polaritons in silicon carbide. The control of thermal emission properties
exhibited by the design is well suited for applications requiring infrared
sources, gas or temperature sensors and nanoscale heat transfer. Our work paves
the way for future silicon carbide based thermal metasurfaces.
