Optical Capture of Optical Nanoparticles: Fundamentals and Applications

A new article published in Optoelectronic Science reviews the basic principles and applications of optical capture of optical nanoparticles. Optical nanoparticles are one of the key elements in photonics. They can not only perform optical imaging on various systems, but also serve as highly sensitive remote sensors.

Recently, the success of optical tweezers in separating and manipulating individual optical nanoparticles has been demonstrated. This opens the door to high-resolution, single particle scanning, and sensing.

This article summarizes the most relevant results in the rapidly growing field of optical capture of individual optical nanoparticles. According to the different materials and their optical properties, optical nanoparticles can be divided into five categories: plasma nanoparticles, lanthanide doped nanoparticles, polymer nanoparticles, semiconductor nanoparticles, and nanodiamonds. For each scenario, the main progress and applications were described.

Plasma nanoparticles have a high polarization rate and high photothermal conversion efficiency, therefore, it is necessary to make a critical selection of their capture wavelength. The typical application of optical capture based on the luminescent properties of plasma nanoparticles is the study of particle particle interactions and temperature sensing. This study was conducted by analyzing the radiation absorbed, scattered, or emitted by nanoparticles.

Lanthanide doped nanoparticles have a narrow emission band, longer fluorescence lifetime, and temperature sensitive emission intensity. This article reviews the temperature sensing of batteries achieved by single optical capture of lanthanide doped nanoparticles. The structural characteristics of the main body of lanthanide doped nanoparticles allow these particles to rotate. For a fixed laser power, the rotational speed depends on the viscosity of the medium. Research has shown that this characteristic can be used to measure intracellular viscosity. In addition, the sufficient surface functionalization of lanthanide doped nanoparticles enables them to be used for chemical sensing.

Dyes are incorporated into polymer nanoparticles to emit light and facilitate tracking within optical traps. This article reviews the research on the dynamics of individual nanoparticles and the characterization of biological samples using particle luminescence tracking ability. It not only helps to gain a more thorough understanding of the optical and mechanical interactions between captured lasers and optical particles, but also points out the enormous potential of combining optical capture with fluorescence or scanning microscopy.

Semiconductor nanoparticles have received widespread attention due to their unique photoluminescence properties, such as tunable emission, low sensitivity to photobleaching, high quantum yield, and chemical stability. This article reviews the research progress on using optical tweezers to study and improve the luminescence performance of individual semiconductor nanoparticles. They also summarized research on using semiconductor particles as local excitation sources for cell imaging.

The fluorescence of nanodiamonds is caused by point defects in the diamond structure. Bibliographic research indicates that there are limited reports on optical capture of nanodiamonds. The first report on this topic shows that a single nanodiamond can be used as a magnetic field sensor. Later, optically captured nanodiamonds were also proven to be useful as cell thermometers.

This review article also reveals how the combination of optical capture and colloidal optical nanoparticles can be used for various applications. Despite the enormous potential of optical tweezers in the study of individual nanoparticles, this field is still in its early stages. Most works focus on application rather than filling knowledge gaps. There are still some unresolved issues.

This review summarizes the challenges faced by optical capture of nanoparticles, including the lack of precise formulas to describe optical force, uncertainty in spatial resolution, and possible sensing biases. This review is expected to promote the continuous enrichment and development of principles, technologies, equipment, and application research in this field.

Source: Laser Net