Uncoated Fiber Tip Research Articles

Reflection near-field scanning optical microscopy: an interferometric approach

An all-fiber near-field scanning optical microscope (NSOM) is demonstrated which allows significant signal enhancement through interferometric mixing and permits phase contrast. An uncoated fiber tip is used both as source and detector in a reflection mode configuration. Pseudoheterodyne detection in a Mach-Zehnder interferometer used in conjunction with the reflection mode NSOM allows the imaging of both opaque and transparent samples with a large signal enhancement. A phase contrast can be observed that may prove useful in the imaging of certain samples such as biological specimens. Images of a diffraction grating and red blood cells are presented in three different operating modes: conventional reflection, reflection with enhanced amplitude contrast, and reflection with phase contrast.

Near field microscopy and lithography with uncoated fiber tips: a comparison

We show that lateral resolution well beyond 100 nm can be obtained in scanning near-field optical microscopy (SNOM) using uncoated glass fiber tips in the internal reflection mode. Exposure of a photosensitive layer through the tip of a tapered optical fiber reveals that the illuminated area underneath the fiber tip is far larger than the best resolution obtained in microscopy. This finding points to the importance of the particular beam path in an internal reflection mode SNOM experiment. Lithographic experiments with metal coated fiber tips show that in this case, the light field emitted by the tip is indeed confined to an area below 100 nm.