NEPEAN, Ontario, Canada, May 30 -- Kevin Kalkhoven has stepped down from his posts as co-chairman, CEO and board member at JDS Uniphase Corp. Jozef Straus has been named CEO and will remain as co-chairman of the company. Kalkhoven will stay with the JDS Uniphase through its fiscal 2001 as a strategic advisor.   Straus has served as president and COO since July 6 of last year when JDS Fitel and Uniphase merged to create JDS Uniphase. Charles J. Abbe has been appointed president and COO. Abbe formerly was the CEO of Optical Coating Laboratory Inc., which JDS Uniphase acquired in February of this year.   JDS Uniphase is in an outstanding position today from the perspective of our financial performance and strength, our market position, our products and our strategy, Kalkhoven said. The company is solidly on course, there is a very strong team to lead the company forward, and I feel confident in turning over responsibility for the company's future to others.