After the postdoctoral fellowship, Johnson was appointed assistant professor of electrical and computer engineering at the
University of Colorado Boulder in 1985, where she co-founded the
National Science Foundation (NSF) Engineering Research Center (ERC) for Optoelectronic Computing Systems and spun off several companies from her research laboratory including ColorLink, Inc which was later sold to RealD, responsible for the technology that helped re-launch the 3D movie industry. Additionally, she co-founded the Colorado Advanced Technology Institute Center of Excellence in Optoelectronics. In 1999, Johnson was appointed Dean of the School of Engineering at
Duke University, which would be later named for distinguished alumnus, Edmund T. Pratt Jr., CEO emeritus of Pfizer Corporation. In 2007, Johnson became the Senior Vice-President and Provost of
Johns Hopkins University. In 2009, Johnson was appointed by
President Obama as the
Under Secretary of Energy for Energy and Environment at the
United States Department of Energy with the unanimous consent of the
United States Senate. She is the founder of Enduring Hydro, a hydropower-focused energy firm. The firm has a joint venture with the New York City-based private equity firm
I Squared Capital (called Cube Hydro Partners), that owns and operates 19 hydropower plants in the Eastern United States. Johnson was elected a member of the
National Academy of Engineering in 2016 for the development and deployment of liquid crystal on silicon display technologies, the basis for high-speed optoelectronic 3D imaging. Johnson has been a director of Minerals Technologies Inc.,
Nortel,
Guidant Corporation,
AES Corporation, and
Boston Scientific. She is currently a member of the Board of Directors of
Cisco Systems. In 2019, she resigned from the board of AES Corporation amid criticism of the company's pollution in Puerto Rico.
State University of New York In April 2017, Johnson was appointed chancellor of the 64-school
State University of New York, assuming the role in September. On June 3, 2020, it was announced that Johnson would resign from her position at the State University of New York to become the next president of
Ohio State University.
Ohio State University Under her presidency at Ohio State, research spending increased by 42%, and faculty attrition was reversed. In addition, significant funds were raised for the university and scholarships increased. In 2023, Johnson "shocked the Ohio State University community" when she resigned from her position as president "just halfway through her contract". According to
The Columbus Dispatch, this was due to Johnson deciding "she could no longer work with
Les Wexner and certain trustees who are loyal to him and who push for his interests". Sources told
The Columbus Dispatch that "Johnson and university leaders agreed not to speak publicly about the details surrounding her resignation", and she was replaced by
Walter E. Carter Jr. the following school year. == Personal life ==