Peter P. Sorokin

Peter Pitirimovich Sorokin, a renowned pioneer in laser science, passed away on September 24, 2015. Peter, an IBM Fellow emeritus, devoted his career to understanding, creating and using light. His 1966 discovery of organic dye lasers, with their continuous tunability over a broad range, led to a revolution in optical spectroscopy and nonlinear-optics, and opened a path to fundamental studies in physics, chemistry, biology, and medicine. For his discoveries Peter was honored with the Franklin Institute’s Albert A. Michelson Award, the Optical Society of America’s R. W. Wood Prize, the National Academy of Sciences’ Cyrus B. Comstock Prize, the Technion’s Harvey Prize, and the American Physical Society’s Arthur Schawlow Prize in Laser Science. He was a Fellow of the American Physical Society and the Optical Society of America, and a Member of the National Academy of Sciences.

Peter was born on July 10, 1931, in Boston, Massachusetts, the son of Pitirim Aleksandrovich Sorokin and Elena Baratinskaya Sorokin. He grew up in Winchester, MA and attended Harvard University, where he received a B.A. in 1952 and a Ph.D. in Applied Physics in 1958. For his Ph.D. thesis research, under Nicolaas Bloembergen, he created an innovative NMR technique for measuring chemical shifts in cesium halides.

Peter joined IBM in 1958, expecting to continue NMR research, but a new field of science was about to be born, changing Peter’s career forever. In December 1958, Charles Townes and Arthur Schawlow published a paper in Physical Review describing how an optical maser (later named the laser by Gordon Gould) might be achieved. This paper initiated a global race to build the first working laser. Peter jumped in, conceiving that calcium fluoride crystals, doped with either uranium or samarium, might function as laser media - with total-internal-reflection providing feedback. The race was won by Theodore Maiman at Hughes Research Labs in Malibu, California, whose ruby laser used a flashlamp to excite chromium ions in a ruby crystal. Maiman’s laser, elegant, simple, and amazingly powerful, led Peter and IBM colleague Mirek Stevenson to switch to a flashlamp-pumped crystal-rod design. In November 1960, just two weeks after moving from an IBM lab in Poughkeepsie, NY to the brand new IBM Thomas J. Watson Research Center in Yorktown Heights, NY, Peter and Mirek flashlamp-pumped a cooled crystal of uranium-doped calcium fluoride. The crystal lased – becoming the world’s second laser. Soon afterwards, their samarium-doped crystal worked as well - the third laser. For IBM, these were welcome world-class discoveries from the new IBM Research Center. For Peter, they marked the beginning of a sustained and fruitful career in laser science.

Peter became interested in organic dyes in 1964. He discovered the saturable-dye Q-switch - the first passive device used to produce “giant” (Q-switched) laser pulses. In 1966, he and colleague John Lankard formed a laser comprising a solution of the fluorescent dye chloro-aluminum phthalocyanine in ethyl alcohol between two parallel mirrors. Optically pumping the dye with a ruby laser pulse, they observed intense infrared laser action. The organic dye laser was born. That same year Peter and colleagues made another major discovery, observing stimulated-electronic-Raman scattering (SERS) in potassium vapor using a Raman-shifted ruby laser. Peter made major advances in extending the spectral range of laser sources using nonlinear “optical-mixing” in atomic vapors. These experiments translated the tunability of dye lasers far into the ultraviolet (UV) and infrared (IR) regions of the spectrum. Building on these advances, he and his colleagues developed innovative techniques for studying chemical dynamics. One such technique, time-resolved infrared spectral photography, captured an entire infrared spectrum with a single laser pulse, initially in nanoseconds, but later in just femtoseconds. This technique enabled Peter to examine rapid photolytic reactions of molecules of atmospheric importance.

Aside from his scientific work, Peter loved spending time outdoors. He walked and hiked whenever he could, whether in South Salem, New York, during the 21 years he lived there, or on mountain trails throughout the Northeast. He also loved spending summers at the family cabin in Canada and could adeptly cut the grass there using a traditional scythe. He enjoyed listening to classical music. Peter had a whimsical sense of humor and laughed easily. He delighted in encouraging his family in all their intellectual and creative pursuits.

Peter was a unique and kind individual, who will be missed by his family, friends, and colleagues. He was gentle, generous, highly principled, and a loving husband, father, and brother. He is mourned by his wife, Anita, their children, Elena and Paul, and his brother, Sergei.

Authors

Donald S. Bethune
IBM Almaden Research Center
San Jose, California
dbethune@us.ibm.com

James J. Wynne
IBM Thomas J. Watson Research Center
Yorktown Heights, New York
jjwynne@us.ibm.com

Peter P. Sorokin, 84, physicist
Lewisboro Ledger