 
 <prompt> Wetin solid state lighting dey use? Based on di previous question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: In recent years light emitting diodes (LEDs) dey become more efficient well well wey dey lead to plenty plenty increase for the use of solid state lighting. For many situations, controlling the light wey LEDs dey emit fit dey most effective if we use the principles of nonimaging optics. 