Fig. 7: Broadband near-IR LED.
From: Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

a Spectral output of the constructed broadband infrared (IR) light-emitting diode (LED). The inset shows the LED design, comprising a blue pumping LED (b), combined with the CaS:Eu,Tb broadband infrared phosphor (d), under operation below a 780-nm high-pass cut-off filter without (c) and with (e) the infrared phosphor present, captured by a camera with a near-IR responsivity.