We accurately measure the profiles of a reflected divergent beam under a very common surface plasmon resonance configuration in both the near- and far-field regions. Through analysis of the normalized beam shapes, significant propagation-dependent distortion is experimentally revealed. The results are in very good agreement with the theoretical estimations, considering the nonlinear phase distribution within the angular range covered by the focused beam. The corresponding minimal positions of the angular reflectance spectrum measured at different locations could shift as much as a few tens of millidegrees. The propagation-dependent Goos–Hänchen shifts are also accurately obtained, and they significantly deviate from the estimates based on the traditional linear phase response but match very well with the simulation results from our model. This verifies our previous theoretical predictions of the propagation-dependent beam distortion, and it could have further implications for various sensing and device applications.
© 2011 Optical Society of America
Optics at Surfaces
Original Manuscript: November 9, 2010
Manuscript Accepted: November 29, 2010
Published: January 28, 2011
Yuhang Wan, Zheng Zheng, and Jinsong Zhu, "Experimental observation of the propagation-dependent beam profile distortion and Goos–Hänchen shift under the surface plasmon resonance condition," J. Opt. Soc. Am. B 28, 314-318 (2011)