Fast-response signal upconversion by the use of a 'time-space conversion' method

摘要

Lanthanide-doped phosphors achieve signal wavelength conversion between visible and infrared communication systems. A long lifetime of their excited states is advantageous for inducing two-photon absorption that realizes upconversion. The long lifetime, however, restricts the conversion rate to ～500bit/s because of the afterglow. This contradiction was solved by embedding a phosphor (YbEr:Gd_2O_2S) in a rotating disk. When an infrared (940 nm) pulse train of 1 Mbit/s (time domain) was focused on the disk, a fluorescent dot array (space domain) was created and moved with the disk rotation. Consequently, a visible (～550 nm) pulse train was detected on the dot trajectory.