Amplitude and phase evolution of optical fields inside periodic photonic structures

Abstract

Abstract-Optical amplitude distributions of light inside periodic photonic structures are visualized with subwavelength resolution. In addition, using a phase-sensitive photon scanning tunneling microscope, we simultaneously map the phase evolution of light. Two different structures, which consist of a ridge waveguide containing periodic arrays of nanometer scale features, are investigated. We determine the wavelength dependence of the exponential decay rate inside the periodic arrays. Furthermore, various interference patterns are observed, which we interpret as interference between light reflected by the substrate and light inside the waveguide. The phase information obtained reveals scattering phenomena around the periodic array, which gives rise to phase jumps and phase singularities. Locally around the air rods, we observe an unexpected change in effective refractive index, a possible indication for anomalous dispersion resulting from the periodicity of the array.

Imaging of surface plasmon polariton interference using phase-sensitive photon scanning tunneling microscope

“…In order to separate the multiple SPPs, one should measure both amplitude and phase of the optical field on the metal surface. In this work, we use a heterodyne interferometric (or phase-sensitive) PSTM [9][10][11][12][13] to measure the complex SPP interference field, generated on a gold-air interface by simultaneously exciting two SPP waves on the interface: one using prism coupling and another using grating coupling [3]. The interference between the two SPP waves, having same energy and propagating in different in-plane directions, manifests as a beating pattern formed along the direction of k x .…”

“…The interference between the two SPP waves, having same energy and propagating in different in-plane directions, manifests as a beating pattern formed along the direction of k x . The two SPP modes are separated by filtering the desired wave vectors in the two-dimensional Fourier Transform image of the total optical field [11].…”

Near field investigation of surface plasmon polaritons

“…A complete description of the optical field requires the measurement of amplitude, phase and polarization. The amplitude and phase of the evanescent waves on a sample surface can be measured by inserting the PSTM into one arm of a Machzehnder type interferometer [102,103,104]. Recently, Burresi and coworkers have modified a PSTM to probe also the polarization state of the optical near-field [105].…”

“…3.11a. To investigate the different spatial frequencies in the optical field, a 2D Fourier transform of the optical field is taken [104], of which a zoom-in region is shown in Fig. 3 between the propagation direction of the prism-coupled and the grating-coupled SPPs.…”

“…To separate the SPPs from the diffracted order and thereby to measure the propagation length of the SPPs, a two-dimensional Fourier transform analysis [104] of the PSTM images is performed. The Fourier transform of the complex optical field measured on the exposed grating ( to the SPPs.…”