Upconversion
Refers to the emission of light when certain characterstics are met with Phosphorous and Lanthanoid elements
A Sciencedirect.com webpage discusses the use of upconversion for the detection of 1.3μm luminescence.
"Conversion of IR radiation with λ=1.3 μm into the visible by use of nonlinear sum-frequency mixing in a LiIO3 crystal was studied experimentally. Advantages and disadvantages of the up-conversion method compared with other methods for NIR-light detection are discussed."
Lanthanoid elements when "upconverted" emit light.
Upconversion fluorescence imaging technique with excitation in the near-infrared (NIR) region has been used for imaging of biological cells and tissues. This has several advantages, including absence of photo-damage to living organisms, very low auto-fluorescence, high detection sensitivity, and high light penetration depth in biological tissues.
The near-infrared region is also called Infra Red-A
Also there is an "Energy Upconversion" Discussed in the following
PNOS.org webpage excerpt:
The photophysical events preceding electron transfer in green plant and bacterial photosynthesis have been the subject of much speculation and experiment (1-8).