Search

A wide variety of near-field optical phenomena are described by the interaction of dipole radiation with a nanophotonic system. The electromagnetic field due to the dipole excitation is associated with the Green’s function. It is of great interest to investigate the dipole interaction with a photonic system and measure the near-field Green’s function and the quantities it describes, e.g., the local and cross density of optical states. However, measuring the near-field Green’s function requires a point-source excitation and simultaneous near-field detection below the diffraction limit. Conventional single-tip near-field optical microscope (SNOM) provides either a point source excitation or amplitude and phase detection with subwavelength spatial resolution. The automated dual-tip SNOM, composed of two tips, has overcome the experimental challenges for simultaneous near-field excitation and detection. Here, we investigate the dipole emission in the near-field of a dielectric metasurface using the automated dual-tip SNOM. We have analyzed the near-field pattern and directional mode propagation depending on the position of the dipole emission relative to the metasurface. This study is one further step toward measuring the dyadic Green’s function and related quantities such as cross density of optical states in complex nanophotonic systems for both visible and near-infrared spectra.

This work reports the first images obtained by combining an infrared aperture scanning near-field optical microscope (SNOM) with a quantum cascade laser (QCL). The future potential of this set-up is demonstrated by a preliminary study on an OE33 human oesophageal adenocarcinoma cell in which the cell is imaged at 1751 cm-1, 1651 cm-1, 1539 cm-1 and 1242 cm-1. In addition to the 1651 cm-1 image, three other images were acquired within the Amide I band (1689 cm-1, 1675 cm-1 and 1626 cm-1) chosen to correspond to secondary structures of proteins. The four images obtained within the Amide I band show distinct differences demonstrating the potential of this approach to reveal subtle changes in the chemical composition of a cell.

We show that the combination of a scanning near field optical microscope and an infra-red free electron laser yields chemical images with sub-cellular spatial resolution that have the potential to provide a diagnostic for oesophageal adenocarcinoma.

A Scanning Near-field Optical Microscope (SNOM) was used to inscribe locally limited Surface Relief Gratings (SRGs) on pDR1M, which is an azo-polymer film. The influence of parameters such as the line scanning time and the line spacing on the amplitude and the period of the gratings is discussed. SRGs have been used to orient Liquid Crystals (LCs), where the LC alignment takes place due to the elastic distortions of the nematic medium close to the surface. In addition, the photoalignment of the azo-chromophores was also used to induce LC alignment. In this work we investigate the use of local SGRs together with the photoalignment to get a local control of the LC alignment properties. The advantage of this method is that it is reversible and the gratings can easily be erased.

A new aperture scanning near-field optical microscope operating in the intermittent contact mode using a non-bent optical fiber is introduced. The microscope was built modifying a classical scanning near-field optical microscope (SNOM) unit introducing a patented probe-holder (MTP) which contains a piezo-motor and a bimorph-transductor. The main advantages of the present set-up in terms of stability, versatility, optical resolution, and quality of the collected signals are described. The instrument works properly while exerting a minimum perturbation on the sample thus overcoming the major drawbacks of different SNOM-based imaging modes and allowing to study very delicate samples including living cells in physiological environment.

We report time-resolved acoustic measurements in the picosecond range performed with a 100 nm lateral resolution. A near field optical microscope operating in reflection geometry and coupled with a standard picosecond acoustic setup is described. Results obtained on thin film are discussed and prove that the sensitivity of our system allows the observation of thermal features and acoustic signals such as echoes and surface waves. Patterned structures made of submicrometric metallic dots have also been studied: it is demonstrated that, owing to the high lateral resolution which we obtained, vibrational modes of a single dot are detected.

International audience; We report on an apertureless scanning near-field optical microscope operating in reflection mode and based on a commercial AFM. We discuss the optical origin of the near-field images of a test sample. We show that the optical images have a sharp contrast depending on the state of polarization of the incident light.

International audience; The equivalence between the illumination and collection modes of the Scanning Near-Field Optical Microscope (SNOM) is established based on the reciprocity theorem for electromagnetic fields. This equivalence holds provided that the sample and the optical elements involved are linear and characterized by symmetric constitutive tensors. 0 1997 Published by Elsevier Science B.V.

Using degenerate four-wave mixing in an Fe:LiNbO(3) 0.04-wt. % crystal and an external-reflection near-field optical microscope, we have achieved phase conjugation of light emitted by a fiber tip. We observe that the phase-conjugated light at a wavelength of 633 nm can reach a power of ~0.1 nW and produce a 180-nm-wide spot image in the near-field microscope. This is the first direct demonstration, to our knowledge, of the phase conjugation of near-field components of optical fields.