what is your required distance between the switches?
you can look for cables on Mellanox website (Cables - Mellanox Technologies)
There are serious cable lengths up to 300 meter. If you need larger distance, you will have to use a long haul solution:
Mellanox Technologies: Long-Haul Systems
trying to extend the length beyond 300M using an MPO/MTO connector is probably not the best idea. the link is going to suffer from retries and disconnects.
Thanks!