Luminescent detector for free-space optical communication

An apparatus comprising:

• a wavelength-shifting element comprising:
• a photoluminescent wavelength-shifting material configured to:
• receive, from a first direction, an input-light data signal comprising a first range of wavelengths;
• absorb at least a portion of the received input-light data signal;
• and
• produce, based on an upper-state lifetime of the photoluminescent wavelength-shifting material, an emitted-light data signal comprising a second range of wavelengths;
• a plasmonic structure that emits the emitted-light data signal in an opposite direction from the first direction;
• a focusing element configured to:
• receive, from the opposite direction, at least a portion of the emitted-light data signal;
• concentrate the received portion of the emitted-light data signal;
• and
• produce a concentrated-light data signal;
• and
• a photodetector configured to:
• receive the concentrated-light data signal;
• and
• produce an electrical current corresponding to the concentrated-light data signal.