Using a single strand implies some flavor of WDM, which adds another layer of complexity where it may or may not be needed (think: Keep it Simple).
Using a traditional dual strand setup makes troubleshooting easier, the troubleshooting tools simpler, and probably less expensive. "Expensive" is relative; if you're out of glass, it's usually cheaper to double up the signaling that it is to bury more fiber.
Equipment using WDM tend to be more expensive as well, compared to traditional two-strand equipment.
One generally doesn't see single strand optical implementations - single pair vs. two pair is a more common set of alternatives.
The decision criteria is usually based on the SONET protection scheme you are using to protect your circuits in the event of a path outage. See, for instance, this article: http://www.ncomm.com/new_site/main/Sonet_05202004_jsb.htm regarding SONET protection schemes.
If you're not asking about a SONET / DWDM context, my apologies. Even in a LAN or Metro Ethernet environment, however, one almost always uses dual strands (i.e. pairs) of fiber for connectivity.
Both of them can be best for your requirement, just see what infrastructure you have. Dont see too much advantage of one over the other.
In my opinion Single strand are not very complex or costly as there is just one splitter(passive component) extra at both end from the 1 pair fiber connectivity.
Dont see troubleshooting in one fiber different than a pair. In single strand i think u will not have UDLD kind of problem as if fiber break there will be same effect at both ends.
Can you provide some more info what you want to connect and what speed.
Are you just looking some simple solution where One different wavelength is used for each side or something more complex.
It is not a matter of which is "better". When configured correctly, either choice can provide an error free interconnect solution.
The majority of optical networks are built using dual strand configurations; mainly due to cost and ease of understanding. Single strand operation requires the addition of optical filters to combine/separate the individual light paths traveling over the fiber.
We are not clear on what is driving your single vs dual strand question.
Hope this helps!
In my opinion, also dual. I've seen some metro projects in the NL using single strand with 100BX optics and both single and dual-strand can deliver you an error-free connection. The price-difference between single and dual-strand is nihil for the fiber itself, but the optics are generally a little more expensive for dual-strand. For mega projects it can be feasible to use single strand, but in all other cases i use duals. More complexity means that more can be broken or misunderstood.