Determination of local refractive index variations in thin films by heterodyne interferometric scanning near-field optical microscopy

Abstract

We report on a heterodyne interferometric scanning near-field optical microscope developed for characterizing, at the nanometric scale, refractive index variations in thin films. An optical lateral resolution of 80 nm (lambda/19) and a precision smaller than 10(-4) on the refractive index difference have been achieved. This setup is suitable for a wide set of thin films, ranging from periodic to heterogeneous samples, and turns out to be a very promising tool for determining the optical homogeneity of thin films developed for nanophotonics applications.

Deterministic Coupling of a Single Nitrogen Vacancy Center to a Photonic Crystal Cavity

“…This in-plane resolution may be improved substantially using cavity modes with small feature sizes, as in slot-waveguide cavities [23]. These qualities make the SCM a promising tool for label-free single molecule studies [2,24] or high-resolution studies of local index variations in thin films [25,26]. We note that a scan acquired by moving the photonic crystal membrane across the surface may need to be de-convolved by the response function of the cavity mode, as described in Appendix G. Beyond high resolution and throughput, the SCM adds the capability to modify the spontaneous emission rate to near-field microscopy.…”

“…This in-plane resolution may be improved substantially using cavity modes with small feature sizes, as in slot-waveguide cavities . These qualities make the SCM a promising tool for label-free single molecule studies , or high-resolution studies of local index variations in thin films. , Beyond high resolution and throughput, the SCM adds the capability to modify the spontaneous emission rate to near-field microscopy. This opens new possibilities for direct investigations of decay channels of optical emitters, such as light-emitting diodes or fluorophores; for instance, by monitoring the emission intensity while effecting a known change in the radiative emission rate, the relative nonradiative recombation rate may be inferred, allowing a direct estimate of the radiative quantum efficiency of the material.…”

Scanning Near-Field EllipsometryMicroscopy: imaging nanomaterials with resolution below the diffraction limit

“…Fig. 3 and 4 show contact mode AFM images, as well as the photodetector output signal captured on a poly(methyl methacrylate) (PMMA) thin film 30 that was loaded with 80 nm diameter silver nanoparticles. The Ag nanoparticles are clearly differentiated, i.e.…”

Thickness measurements of metal thin films with a plasmonic near-field scanning nanoscope using a resonant ridge aperture

“…[1][2][3][4] As the thickness of these thin films has decreased to the nanoscale, many types of deposition techniques have been developed in order to obtain precise fabrication. [1][2][3][4] As the thickness of these thin films has decreased to the nanoscale, many types of deposition techniques have been developed in order to obtain precise fabrication.…”

“…[1][2][3][4] As the thickness of these thin films has decreased to the nanoscale, many types of deposition techniques have been developed in order to obtain precise fabrication. [1][2][3][4][5][6][7][8][9] Therefore, the ability to accurately measure thickness is significant to the successful design and fabrication of optical and electrical devices. Of particular importance is the accurate measurement of the film thickness because variations in film thickness can affect many properties, and thus, film thickness represents a key parameter for determining the properties of the film.…”