Apertureless scanning near‐field optical microscopy for ion exchange channel waveguide characterization

Abstract

SummaryWe report the characterization of an integrated Ag + /Na + ion exchange waveguide realized in a silicate glass substrate using apertureless scanning near-field optical microscopy. Our experimental set-up is based on the combination of a commercial atomic force microscope with an optical confocal detection system. Thanks to this system, the topography and evanescent optical field at the waveguide top surface are mapped simultaneously. Also, the process of apertureless scanning near-field optical microscopy image formation is analysed. In particular, fringe patterns appearing in the image reveal the intrinsic interferometric nature of the collected signal, due to interference between the field scattered by the tip end and background fields related to guide losses. We give a quantitative interpretation of these fringes. Evanescent intensity mapping on the sample surface allowed us to extract physical waveguide parameters. In particular, it shows an unambiguous multimode beat along the waveguide propagation axis. Furthermore, we show that analysis of this intensity profile reveals back-reflection effects from the waveguide exit facet. The resulting standing waves pattern allows us to evaluate the eigenmode propagation constants.

Probing photonic and optoelectronic structures by Apertureless Scanning Near‐Field Optical Microscopy

“…It corresponds to the 2D optical signal recorded on the waveguide/air interface, which is related to the evanescent tail of the guided waves. As shown recently by Blaize et al (2003), Fourier analysis of such an image reveals three kinds of fringes systems. The two first kinds are oblique fringes.…”

Polarization-Modulation Techniques in Near-Field Optical Microscopy for Imaging of Polarization Anisotropy in Photonic Nanostructures

“…The complete optical characterization of such photonic structures is thus very important. The possibility of characterizing the reflectivity response of DBRs, and in particular the dependence on the polarization state, prior to their implementation in actual laser systems is even more appealing [90,91]. In the experiment presented here we have applied PM-SNOM to get an insight into the polarization properties of DBR structures.…”

Sub-wavelength patterning of the optical near-field

“…In order to extract the near-field information, the collected signal is demodulated at the oscillation frequency of the cantilever. Under this operation mode the signal measured by an ASNOM is known to be proportional to the electric field intensity below the scanned tip [21,22]. Figure 3(b) shows a typical ASNOM measurement recorded on the fabricated sample when the illumination conditions closely match the ones used in the simulation shown in Fig.…”