Mlm. Balistreri et al., Visualization of mode transformation in a planar waveguide splitter by near-field optical phase imaging, APPL PHYS L, 79(7), 2001, pp. 910-912
The gradual transformation of a guided TM00 mode into an "intermediate" dou
ble mode by a splitting junction has been investigated with a phase-sensiti
ve photon scanning tunneling microscope. Field profiles and wave vectors of
the modes have been directly determined from the phase information. Via a
Fourier analysis of the measured phase and amplitude maps the decay of the
TM00 mode and buildup of the intermediate mode have been directly visualize
d. Phase singularities and phase jumps in the transition region underline t
he mode transformation process. Finally, a partial polarization conversion
of the TM modes to TE-polarized modes has been observed. (C) 2001 American
Institute of Physics.