Solid-state lighting with reduced light pollution

Motivated by the goal to reduce scattering and light pollution from light-emitting diodes (LEDs), proof-of-concept solid-state white lighting prototypes—based on commercially available LEDs combined with commercially available yttrium aluminum garnet (YAG) and nitridosilicate (NS) phosphor blends—have been developed with minimal emission in the violet-blue spectrum via two different designs. In one design, green-yellow emitting YAG and orange-red emitting NS phosphors are blended in a transparent silicone matrix so that violet-blue light from the pump LED is attenuated and only the green to red light from the excited phosphor blend is externally emitted. In the other design, using a violet-blue LED combined with a less attenuating YAG-NS phosphor blend, a commercially available 500 nm cut-on wavelength dichroic longpass filter internally reflects the violet-blue LED pump light while transmitting the green to red light from the excited phosphor blend. In both cases, the phosphor blend is located remotely from the LED by placing it inside a thin-walled aluminum tube light guide.