With the help of $1.7 million in tax credits from the state of Massachusetts, !%IPG Photonics%! will add 175 employees as part of an $18 million plan to expand its facility by more than 100,000 sq ft. Lt. Gov. Timothy Murray joined state and local officials at the fiber laser maker’s Oxford facility to announce both the tax credit under the Economic Development Incentive Program and a $2.2 million MassWorks Infrastructure Grant for the town of Oxford. Oxford, with the support of other towns, will use the funds to install a sewer extension to open areas for economic development.