Which hardware module connects SC fiber optic cables to device and changes electrical signals to optical signals?

A Gigabit Link Module (GLM) is a proprietary Cisco module used in specific older Catalyst switch uplinks and is not the standard transceiver type associated with SC fiber optic cable termination.

A Fabric Extender Transceiver (FET) is a specialized Cisco module designed exclusively for Fabric Extender (FEX) uplink connections and does not serve as a general-purpose SC-connector transceiver.

The Gigabit Interface Converter (GBIC) is a hot-swappable transceiver standard defined to use SC-type duplex fiber optic connectors and performs bidirectional conversion between the electrical signals of a network device and the optical signals carried over fiber cable. GBICs are the legacy 1 Gbps transceiver form factor specifically standardized with SC connectors, distinguishing them from newer SFP modules that use the smaller LC connector.

Small Form-factor Pluggable (SFP) transceivers use LC fiber optic connectors rather than SC connectors, and represent a newer, smaller form factor that superseded GBICs.