Small-angle measurement based on surface-plasmon resonance and the use of magneto-optical modulation

A new, to our knowledge, optical method for small-angle measurement based o n surface-plasmon resonance (SPR) is presented. In this method the high sen sitivity of the phase of SPR to the angle of incidence is employed to impro ve the resolution of the measurement of the angle. Small-angle measurement is performed by the monitoring of the phase shift resulting from the minute change of the angle of incidence with the use of magneto-optical modulatio n. The validity of this method is demonstrated, and a measurement resolutio n of 0.2 are sec is achieved experimentally. (C) 1999 Optical Society of Am erica. OCIS codes: 120.5700, 240.6680, 230.3810, 120.3930.