SAN FRANCISCO, Calif., May 3 -- Arthur L. Schawlow, one of the pioneers of laser technology and a Nobel laureate, has died at the age of 77. Stanford University said Schawlow, an emeritus professor of physics, died at a hospital in Palo Alto, Calif., of congestive heart failure and pneumonia following a long battle with leukemia. While a number of scientists were credited with developing the technology that went into building the first laser, Schawlow and his co-inventor Charles Townes were the first to publish a practical guide to making a laser in 1957. In 1981 Schawlow received the Nobel Prize for his work in laser spectroscopy.