Just found the answer. If you remove the sprint name altogether, it redirects to the current sprint.
EDIT: Updated Oct. 2018 for Azure DevOps
For Azure DevOps, the following URL works:
New Azure DevOps URL format:
https://dev.azure.com/[Company]/[Project]/_sprints/backlog/[Team]
Old Azure DevOps (VSTS) URL format:
https://[Company].visualstudio.com/[Project]/_sprints/taskboard/[Team]/
Previously in TFS, the URL was:
http://[Server]/tfs/[Project]/[Team]/_backlogs/TaskBoard#_a=people