Near-field microscopy with a scanning nitrogen-vacancy color center in a diamond nanocrystal: A brief review

Abstract

We review our recent developments of near-field scanning optical microscopy (NSOM) that uses an active tip made of a single fluorescent nanodiamond (ND) grafted onto the apex of a substrate fiber tip. The ND hosting a limited number of nitrogen-vacancy (NV) color centers, such a tip is a scanning quantum source of light. The method for preparing the ND-based tips and their basic properties are summarized. Then we discuss theoretically the concept of spatial resolution that is achievable in this special NSOM configuration and find it to be only limited by the scan height over the imaged system, in contrast with the standard aperture-tip NSOM whose resolution depends critically on both the scan height and aperture diameter. Finally, we describe a scheme we have introduced recently for high-resolution imaging of nanoplasmonic structures with ND-based tips that is capable of approaching the ultimate resolution anticipated by theory.

Coherence and aberration effects in surface plasmon polariton imaging

“…The fiber tip is glued on a quartz tuning-fork and the shear-force coupled to a counter-reaction electronics is used to bring the tip down in the near field and to keep it around 40 nm from the gold surface (our methodology is discussed in refs. [60][61][62]). When light is guided through the fiber down to the aperture (λ = 633 nm), the latter reacts mainly as a pair of electric and magnetic dipoles located in the aperture plane.…”

“…The principle of the NV-based NSOM is to attach a diamond nanocrystal (25 nm diameter) containing one or few NV centers whose fluorescence can be excited using a laser (λ = 532 nm) guided through the fiber. The complete protocol of fabrication and use of this system is detailed in a recent review paper [61]. Now, the point is that if the diamond contains several NVs the probability that a dipole possesses a vertical component is higher.…”

“…This is specially the case in the NV-based NSOM method where the NV fluorescence is excited by a laser light in the λ ∼ 515−532 nm spectral region [23,24,61,62]. The problem here is that usual coverslips generate their own fluorescence, in the same spectral band as NVs do, and it becomes impossible to work in the quantum regime, i.e., to build a g (2) (τ ) function presenting an antibunching g (2) (0) ≃ 0 which is the signature of the single-photon emission process [61]. To solve this issue we therefore shifted to fused silica coverslips with lower optical index n ′ g ≃ 1.46 than usual glass n g ≃ 1.52 but which in turn generates a much lower spurious fluorescence background and are better adapted to microscopy applications with NVs and NSOM.…”

Nanoscale Sensing Using Point Defects in Single-Crystal Diamond: Recent Progress on Nitrogen Vacancy Center-Based Sensors

“…In recent years, the highly-photostable emission of individual NV centers has triggered several efforts to realize near-field sensing based on NV centers [8,26,122,123]. In general, near-field-based imaging, where a sample is illuminated by the near-field of a light source, allows a higher resolution than far field-based techniques and is able to beat the Abbé limit of resolution.…”

“…Single NV centers were used as nano-sized light-source that is brought within <100 nm of the sample in a SNOM setup [25,123,124]. A nanodiamond (ND) attached to the end of a SNOM tip achieved a resolution of around 50 nm when imaging metallic nanostructures, thus beating the Abbé limit of resolution (see Figure 7).…”