1G or 10G SFP Transceiver?

Q: I have 10G fiber cable that we do not need, I was curious to know if I could use a 1G SFP module instead of 10G SFP+ module?

A: 1.So things you need to know is what dealing with the fiber.

2.Distance - how far are you going?

3.Diameter of the cable - can be read off of the cable ends in µm (micron).
According to the diameter of the actual strand of fiber in the core of the fiber cable, fiber cable comes in 3 main types, 9µm single-mode, 50µm multi-mode, and 62.5µm multi-mode. If you have single-mode fiber, any single-mode optics of any speed will work with the fiber. However, if the 10G fiber cable is multi-mode, you might need a "launch cable" to get the right size.
If your cabling installation was built for 10G, it's probably 50µm OM3 or OM4 fiber. This might be a problem, if your 1G SFP modules are designed to use 62.5µm fiber (OM1). If this is the case, you should also get some launch cables that convert between 62.5 and 50µm core diameter for best link quality and stability.

Also you can identify the 10G fiber cable from the color, multi-mode fiber cable has ratings of OM1-4. OM1 and OM2 are orange, OM3 and OM4 are teal. Generally teal is used for 10 gig and is laser optic optimized. Single-mode fiber is yellow.

4.Fiber optic transceiver type, SX = Short Haul, LX = Long Haul, depending on length of the run. SX type fiber transceivers are used with multi-mode fiber cable, LX type fiber transceivers are used with single-mode fiber cable.

From the above, you will need to get the right SFP fiber optic transceiver to match up with the type of cable - Multi-mode or single-mode.