Electrical board to board connectors, what is an optical switch

ON Semiconductor MOCD217R2M in Reel. SOIC8 SMT Dual Channel 30 V 2500 Vrms Phototransistor Optocoupler

https://www.futureelectronics.com/p/semiconductors--optoelectronics--isolation-components-optocouplers/mocd217r2m-on-semiconductor-4416012