WASHINGTON — Valentin Gapontsev is the kind of immigrant U.S. President Donald Trump’s administration has said it prefers: one who can contribute to economic growth. The Soviet-trained scientist emigrated to the United States in the early 2000s and built a $7 billion technology firm that now employs about 2,000 high-paid specialists around the country. Gapontsev even helps the United States chip away, slightly, at the trade deficit with China: His Oxford, Massachusetts-based IPG Photonics generates nearly half of its $1.5 billion in annual revenue from Asia’s largest economy. For his contribution to the local community, the Oxford Business Association in 2013 presented Gapontsev with its Centennial Award, an honor it has given to only two other individuals over three centuries: Elliot Joslin, a pioneer in the treatment of diabetes, and Clara Barton, the founder of the American Red Cross. Five years later, the U.S. citizen an industry group has called a “father of the fiber laser industry” was included in another select group — a move that would pitch him into battle with his adopted country for 18 months. In January 2018, the Treasury Department put Gapontsev on its ...