We describe a time-division interferometer based on the Sagnac geometry for monitoring ultrafast changes in the real and the imaginary components of the refractive index as well as phase changes that are due to surface displacement. Particular advantages of this interferometer are its simple common-path design and operation at normal incidence with a microscope objective for both pumping and probing. Operation is demonstrated by detection of temperature changes and coherent phonon generation in a gold film.
© 1999 Optical Society of America
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(320.7120) Ultrafast optics : Ultrafast phenomena
(320.7130) Ultrafast optics : Ultrafast processes in condensed matter, including semiconductors
David H. Hurley and Oliver B. Wright, "Detection of ultrafast phenomena by use of a modified Sagnac interferometer," Opt. Lett. 24, 1305-1307 (1999)