We　theoretically　study　the　average　current　through　a　ring　embedded　with　multiple　quantum　dots　in　each　arm　subjected　to　a　time-dependent　external　field.　A　current　resonance　band　can　be　observed　in　a　six-quantum-dot　system.　In　the　presence　of　a　time-dependent　external　field,　mutual　transformation　occurs　between　the　resonance　band　and　antiresonance　band,　indicating　an　effective　optically-controlled　quantum　switch　can　be　realized　in　a　wider　quantum　dot＇s　energy　regime.　As　the　Zeeman　effect　is　introduced,　the　conversion　between　100　and　-　100%　for　spin　polarization　p　can　be　realized　by　adjusting　the　frequency　of　time-dependent　external　field,　suggesting　a　physical　scheme　of　an　optically-controlled　spin　filter.　The　present　work　sheds　lights　onto　the　design　and　quantum　computation　of　future　nano-devices.