help !! single mode to multi mode fibre?

[cray]

i have a photodiode with a multimode fibre pigtail. however, most of the devices in my lab have single mode fibre configuration. is it ok for me to use them together?
please help.

thanks
cray

 

[memsman]

I think it's okay to have a pigtailed MMF spliced or connectorized to your SMF configuration.

In fact, most if not all the pigtailed detectors, as far as i know, use MM. This is because losses from single-mode to multi-mode fibers by splicing are about 0.1-0.2dB

The opposite of course is not true, i.e you can't use a pigtailed MMF laser source to couple to a SMF system without mode conversion, otherwise losses will be in the order of 2-3dB

 

[cray]

I think it's okay to have a pigtailed MMF spliced or connectorized to your SMF configuration.

In fact, most if not all the pigtailed detectors, as far as i know, use MM. This is because losses from single-mode to multi-mode fibers by splicing are about 0.1-0.2dB

The opposite of course is not true, i.e you can't use a pigtailed MMF laser source to couple to a SMF system without mode conversion, otherwise losses will be in the order of 2-3dB

Thanks for your reply memsman, i ve tried to splice the pigtail MMF onto a SMF fibre patchcode, but only the fibre core can be successfully spliced. the cladding doesn't completely splice together (i can see a small gap between the cladding). is this ok? what mode do u use when splicing SMF to MMF?
please help.

 

[memsman]

i'm not sure.. but you can try to measure the losses for your spliced SMF/MMF combination trials

Actually, the low loss (0.2-0.3dB) were even measured for non-spliced but close fibers (or better to use a lensed SMF placed at half the working distance) that's why i assume your case will be as good.

In case of lensed SMF, don't worry about angular and lateral misalignments. These are really small with SMF to MMF coupling