Is the SFP optical module a PC or an APC

Standard SFP optical modules are typically PC or UPC, not APC.

SFP (Small Form-factor Pluggable) optical modules generally have flat or slightly curved end faces, making them compatible with PC (Physical Contact) or UPC (Ultra Physical Contact) fiber connectors . The PC connector features a slightly curved polish to reduce air gaps and achieve a return loss of about -40 dB, while UPC is an improved version with a higher-quality polish and return loss around -50 dB . Both PC and UPC connectors can be used interchangeably with SFP modules without causing damage. In contrast, APC (Angled Physical Contact) connectors have an 8-degree angled ferrule designed to minimize back reflection, achieving a return loss of -60 dB or better . Because of this angled design, APC connectors cannot be mated with standard SFP modules, which have flat ports. Attempting to connect an APC fiber to a standard SFP module can cause misalignment, increased insertion loss, and potential damage to the transceiver interface . APC SFP modules do exist, but they are specialized for applications requiring low back reflection and high signal stability, such as PON, FTTH, or long-haul single-mode fiber networks . These modules integrate an APC connector directly into the SFP form factor, unlike standard SFPs which are designed for PC or UPC connections. Key takeaway: For typical SFP optical modules, use PC or UPC fiber connectors. Only use APC connectors with SFP modules specifically designed for APC interfaces to avoid network issues or hardware damage .