Nanometer scale polarimetry studies using a near-field scanning optical microscope

Abstract

We describe a new technique that incorporates polarization modulation into near-field scanning optical microscopy (NSOM) for nanometer scale polarimetry studies. By using this technique, we can quantitatively measure the optical anisotropy of materials with both the high sensitivity of dynamic polarimetry and the high spatial resolution of NSOM. The magnitude and relative orientation of linear birefringence or linear dichroism are obtained simultaneously. To demonstrate the sensitivity and resolution of the microscope, we map out stress-induced birefringence associated with submicrometer defects at the fusion boundaries of SrTiO3 bicrystals. Features as small as 150 nm were imaged with a retardance sensitivity of approximately 3 x 10(-3) rad.

The electric field at the apex of a near‐field probe: implications for nano‐Raman spectroscopy

“…The small size of the source precludes complete polarization, and the ratio of the two polarizations depends upon the numerical aperture of the collection lens. 35 Note that the scales for 1 nm separation are nearly 10 times those at 10 nm. Also shown in the figure is the profile of the z-electric field times its gradient, which will be of interest later.…”

Microscopic Reflection Difference Spectroscopy on Semiconductor Nanostructures

“…Although in the recent few years significant progress has been made in this field [5,6], and spatially resolved images of e.g. strain induced birefringence showing %150 nm details have been reported [7], we argue that spectroscopic measurements are less trivial.…”

“…Also, it has been suggested that the polarization sensitivity is drastically reduced in the near-field regime [13]. Another work, however, reports on a large polarization contrast achievable with a fiber tip [14], although only using a low NA collection objective [7]. Complications might thus arise when performing nRDS in reflection, since incident and reflected light have to pass through the fiber.…”

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

“…Two experimental approaches have been used to rotate the polarization of the probing light, using PEMs and EOMs. The PEM [50,76] provides a sinusoidal phase change δ ∝ sin(ωt), while the EOM [28,48,77,78] is characterized by a linear phase change δ ∝ ωt. The respective Jones matrices are reported in Table 10.2.…”

“…Finally we note that (10.35) is valid even if the sample has birefringence, as long as the birefringence principal axes are coincident to the dichroism ones. Again, the fiber-induced retardance can be taken into account by removing the sample and acting on the paddles in order to zero the harmonic signals [76]. A procedure similar to the one described for the EOM case can be followed to deconvolute the residual tip dichroism [76], and determine the true retardance or diattenuation properties of the samples.…”