Nanocarbon materials are attractive building blocks for future nanoelectronic and nanooptic devices, because they allow achieving new degrees of both performance and functionality—a combination unachievable by most conventional materials.

Nanocarbons possess a variety of nearly ideal, low-dimensional nanostructures with unique properties across a range of physical phenomena ranging from mechanics, thermal physics, and electrochemistry to optics. These, in turn, make them ideal not only for a wide range of applications but as a test bed for fundamental science. Their specific properties are chiefly governed by quantum physics and/or surface effects, and they are significantly different from equivalent macroscopic objects. Structure control is therefore a most crucial issue and a topical research field.

Nanocarbon occurs in six different basic forms: graphene, graphite, fullerenes, nanodiamond, nanotubes, and nanocones. Since the discovery of fullerenes and carbon nanotubes about two decades ago, steady scientific and technological progress on numerous aspects of research related to synthesis, purification, structure, properties, and applications has been observed, as is typical for any new and novel material.

Recent linear and nonlinear spectroscopic and optoelectronic results prove that they have much to offer in the photonics arena. This feature issue presents reviews and research articles in the area of nanocarbon optics and optoelectronics, which help to summarize the emerging broad range of applications and to expand the understanding of their properties.

The close relationship between controlled nanoscale structure and optical properties is described for graphene nanosheets by Seo et al. [1]. Both graphene and carbon nanotubes are particularly interesting since the optical absorption extends smoothly across an extremely wide wavelength range, including the near infrared studied in the modeling paper by Mock [2], and going as far as the terahertz range surface plasmon polariton absorption described by Nguyen et al. [3] in carbon nanotube aerogel sheets.

As presented in two invited papers, extending the absorption range into the near infrared is of great practical importance. Zeng et al. [4] have achieved a substantial performance enhancement of infrared photodetectors based on carbon nanotube arrays. Pan et al. [5] have reviewed the use of neat and chemically modified graphenes to enhance organic solar cell performance. In this case, the unique combination of electrical transport properties, optical transparency, and thermal conductivity achieves substantial device improvements.

The nonlinear optical properties of quantum-confined low-dimensional structures are interesting both as spectroscopic tool from a basic research point of view and as passive mode-locking devices for ultrashort lasers. Pokrass et al. [6] have studied saturable absorption in hybrid carbon nanotube/glass composites, Valadão et al. [7] have determined the nonlinear refractive index of surfactant wrapped carbon nanotubes, and Ruzicka et al. [8] have measured the ultrafast saturation and relaxation behavior of CVD-grown graphene layers. Mou et al. [9] have used carbon nanotubes to mode lock an erbium-doped soliton fiber laser, while Xie et al. [10] have employed graphene to mode lock a solid-state laser in the upcoming 2 µm wavelength range.

In an extremely interesting paper by Zhang et al. [11], white-light amplified spontaneous emission from carbon nanodots is described, pointing the way toward potential lasing application of nanocarbons—a futuristic idea even in an optically pumped context.

In conclusion, this feature issue of Optical Materials Express gives a topical and highly interesting overview of the state-of-the-art in the emerging wide-ranging field of nanocarbon photonics research and offers many possibilities for future research. The field spans the entire spectrum from basic materials research to novel materials for laser and optoelectronic device applications.

We express our gratitude to all reviewers and authors for their efforts in improving the manuscripts during the review process. We also thank David Hagan, Editor-in-Chief of Optical Materials Express, for supporting this feature issue and the OSA journal staff for their excellent support during the review and production.