2ND-HARMONIC GENERATION IN MOLYBDENUM-DISULFIDE

We report the experimental observation and analysis of optical second- harmonic generation in the 3R and 2H polytypes of molybdenum disulfide (MoS2) by a fundamental excitation wavelength of 1064 nm. We include an extension from the literature to account for multiple reflections o f the fundamental, anisotropic optical constants, and strong absorptio n of the second harmonic to deduce the second-order nonlinear dielectr ic susceptibilities. We observe a bulk nonlinearity of d(21)\ = 500 +/ - 200 pm/V for 3R-MoS2. The absence of a signal from 2H-MoS2, a centro symmetric stacking polytype, is consistent with \d(eff)\ < 5 x 10(-2) pmN. (C) 1998 Optical Society of America.