What's the name of this type of Bottom Bikini?
I find the link/address you sent to be inaccessible, sorry. I'd love to help :(
These bikini bottoms are in the category of the Side-Tie Bikini Bottom. This is because some are tied on both sides while these are tied on only one side. They can also be referred to as string bikinis. Check out http://www.victoriassecret.com/swimwear/?ProductID=74914.