“…In many existing FD-NIRS systems [ 19 – 21 , 23 , 25 , 27 , 29 , 30 , 32 , 34 , 35 , 39 – 41 , 44 – 48 , 51 , 52 , 54 , 56 – 58 , 60 – 62 , 65 ], Edge-Emitting Lasers (EELs) have been widely applied as light sources. In an EEL, light is emitted from the edge of the substrate, and an EEL offers relatively high power density and wall-plug efficiency, and good beam uniformity [ 78 ].…”