Since the switch have SFP slots you can purchase a transceiver with fiber interface, according your needings. Pay attention to the fiber specifications (multimode, single mode, etc). Follows the compatible hardware info.
MODULE
3Com Switch 4200G 1-Port 10-Gigabit Module (XFP) 3C17666
GIGABIT SFP TRANSCEIVERS
1000BASE-SX SFP 3CSFP91
1000BASE-LX SFP 3CSFP92
1000BASE-LH SFP 3CSFP97
FAST ETHERNET SFP TRANSCEIVERS
3Com 100BASE-FX SFP (Dual-Mode) 3CSFP9-81
3Com 100BASE-LX SFP (Dual-Mode) 3CSFP9-82
108GIGABIT XENPAK TRANSCEIVERS
10GBASE-LX4 3CXENPAK91
10GBASE-LR 3CXENPAK92
10GBASE-SR 3CXENPAK94
10GBASE-CX4 3CXENPAK95
10GBASE-ER 3CXENPAK96