Mainly because of its very low attenuation rate, 1550nm is the most common wavelength used for telecommunication, particularly for extremely long distance, high bandwidth fiber optic applications. 1550nm light is also generally considered to be “eye safe” (and safe for CMOS camera sensors). For similar reasons, 1550nm light is also favored by some companies for automotive LiDAR applications. 1550nm fiber lasers used in these applications are pumped by diode lasers that emit in the 900nmm band, which potentially could cause damage to both the human eye and CMOS cameras. Blocking light outside of the desired 1550nm range using a Bi1550 filter can therefore be important, while also helping to improve power efficiency and greatly reduce noise. Hardcoated 1mm thick, single-substrate Bi1550 filters offer several size, performance and durability advantages over traditional multi-cavity or laminated filters.