  Ultra-broadband imaging devices with high performance are in great demand for
a variety of technological applications, including imaging, remote sensing, and
communications. An ultra-broadband up-converter is realized based on a p-GaAs
homojunction interfacial workfunction internal photoemission (HIWIP)
detector-light emitting diode (LED) device. The device demonstrates an
ultra-broad response ranging from visible to terahertz (THz) with good
reproducibility. The peak responsivity in the mid-infrared (MIR) region is 140
mA/W at 10.5 microns. The HIWIP-LED shows enormous potential for
ultra-broadband up-conversion covering all infrared atmospheric windows, as
well as the THz region, and the pixel-less imaging of the MIR spot from the CO2
laser is further demonstrated. In addition, the proposed up-converter also
performs as a near-infrared and visible detector under zero bias by using a
bi-functional LED. Thanks to its ultra-wide response, the HIWIP-LED
up-converter has great promise for stable, high-performance ultra-broadband
pixel-less imaging and multi-functional analysis systems.
