A historical overview of nano-optics:From near-field optics to plasmonics

Nano-optics is an emergent research field in physics that appeared in the 1980s,which deals with light–matter optical interactions at the nanometer scale.In early studies of nano-optics,the main concern focus is to obtain higher optical resolution over the diffraction limit.The researches of near-field imaging and spectroscopy based on scanning near-field optical microscopy(SNOM)are developed.The exploration of improving SNOM probe for near-field detection leads to the emergence of surface plasmons.In the sense of resolution and wider application,there has been a significant transition from seeking higher resolution microscopy to plasmonic near-field modulations in the nano-optics community during the nano-optic development.Nowadays,studies of nano-optics prefer the investigation of plasmonics in different material systems.In this article,the history of the development of near-field optics is briefly reviewed.The difficulties of conventional SNOM to achieve higher resolution are discussed.As an alternative solution,surface plasmons have shown the advantages of higher resolution,wider application,and flexible nano-optical modulation for new devices.The typical studies in different periods are introduced and characteristics of nano-optics in each stage are analyzed.In this way,the evolution progress from near-field optics to plasmonics of nano-optics research is presented.The future development of nano-optics is discussed then.

Review: Physical Coloration-Nanoscopic Science and Macroscopic Impact

Physical coloration stimulated the development of a new era of science and technology some hundred years earlier.It is now again presenting us new opportunities and challenges on multiple fronts.This article focuses on a selectively few of them that are more directional in nature:scalable nanomanufacturing of physical coloration,physical amplification of colorimetric sensing,and provision of biophilic lighting with real-time full-spectrum physical coloration.Physical coloration is a rather large multi-dimensional field that is open and awaiting for creative minds and hands.Its impact has been broad and profound to the well-being of humankind.This article attempts to complement the reviews of broad scopes available in literature by one with a narrower focus on the more recent advances on the three fronts.

Call for Papers for Focus Issue of Nano-Optics in COL

Chinese Optics Letters invites original manuscript submissions for a Focus Issue on Nano-Optics to be published in October 2008.Rapid progress of nanoscience and nanotechnology has made significant impact on many academic disciplines and technical fields,particularly in the fields of lasers and optics.This focus issue will include excellent review articles and original contributions covering the rapid advances and tremendous breadth of this emerging technical area.The following is a representative and nonexclusive list of areas in which papers are solicited.

Multifunctional integration on optical fiber tips: challenges and opportunities

.The flat endface of an optical fiber tip is an emerging light-coupled microscopic platform that combines fiber optics with planar micro-and nanotechnologies.Since different materials and structures are integrated onto the endfaces,optical fiber tip devices have miniature sizes,diverse integrated functions,and low insertion losses,making them suitable for all-optical networks.In recent decades,the increasing demand for multifunctional optical fibers has created opportunities to develop various structures on fiber tips.Meanwhile,the unconventional shape of optical fibers presents challenges involving the adaptation of standard planar micro-and nanostructure preparation strategies for fiber tips.In this context,researchers are committed to exploring and optimizing fiber tip manufacturing techniques,thereby paving the way for future integrated all-fiber devices with multifunctional applications.First,we present a broad overview of current fabrication technologies,classified as“top-down,”“bottom-up,”and“material transfer”methods,for patterning optical fiber tips.Next,we review typical structures integrated on fiber tips and their known and potential applications,categorized with respect to functional structure configurations,including“optical functionalization”and“electrical integration.”Finally,we discuss the prospects for future opportunities involving multifunctional integrated fiber tips.

Light scattering and surface plasmons on small spherical particles

Light scattering by small particles has a long and interesting history in physics.Nonetheless,it continues to surprise with new insights and applications.This includes new discoveries,such as novel plasmonic effects,as well as exciting theoretical and experimental developments such as optical trapping,anomalous light scattering,optical tweezers,nanospasers,and novel aspects and realizations of Fano resonances.These have led to important new applications,including several ones in the biomedical area and in sensing techniques at the single-molecule level.There are additionally many potential future applications in optical devices and solar energy technologies.Here we review the fundamental aspects of light scattering by small spherical particles,emphasizing the phenomenological treatments and new developments in this field.

Manipulating Bloch surface waves in 2D: a platform concept-based flat lens

At the end of the 1970s,it was confirmed that dielectric multilayers can sustain Bloch surface waves(BSWs).However,BSWs were not widely studied until more recently.Taking advantage of their high-quality factor,sensing applications have focused on BSWs.Thus far,no work has been performed to manipulate and control the natural surface propagations in terms of defined functions with two-dimensional(2D)components,targeting the realization of a 2D system.In this study,we demonstrate that 2D photonic components can be implemented by coating an in-plane shaped ultrathin(l/15)polymer layer on the dielectric multilayer.The presence of the polymer modifies the local effective refractive index,enabling direct manipulation of the BSW.By locally shaping the geometries of the 2D components,the BSW can be deflected,diffracted,focused and coupled with 2D freedom.Enabling BSW manipulation in 2D,the dielectric multilayer can play a new role as a robust platform for 2D optics,which can pave the way for integration in photonic chips.Multiheterodyne near-field measurements are used to study light propagation through micro-and nano-optical components.We demonstrate that a lens-shaped polymer layer can be considered as a 2D component based on the agreement between near-field measurements and theoretical calculations.Both the focal shift and the resolution of a 2D BSW lens are measured for the first time.The proposed platform enables the design of 2D all-optical integrated systems,which have numerous potential applications,including molecular sensing and photonic circuits.

Development and prospect of near-field optical measurements and characterizations

Scanning near-field optical microscopy （SNOM） is an ideal experimental measuring system in nano-optical measurements and characterizations. Besides microscopy with resolution beyond the diffraction limit, spectroscope with nanometer resolution and other instruments with novel performances have been indispensable for researches in nano-optics and nanophotonics. This paper reviews the developing history of near-field optical （NFO） measuring method and foresees its prospects in future. The development of NFO measurements has gone through four stages, including optical imaging with super resolution, near-field spectroscopy, measurements ofnanooptical parameters, and detections of near-field interac- tions. For every stage, research objectives, technological properties and application fields are discussed.

A polarizing situation： Taking an in-plane perspective for next-generation near-field studies

By enabling the probing of light-matter interactions at the functionally relevant length scales of most materials, near-field optical imaging and spectroscopy accesses information that is unobtainable with other methods. The advent of apertureless techniques, which exploit the ultralocalized and enhanced near-fields created by sharp metallic tips or plasmonic nanoparticles, has resulted in rapid adoption of near-field approaches for studying novel materials and phenomena, with spatial resolution approaching sub-molecular levels. However, these approaches are generally limited by the dominant out-of-plane polarization response of apertureless tips, restricting the exploration and discovery of many material properties. This has led to recent design and fabrication breakthroughs in near-field tips engineered specifically for enhancing in-plane interactions with near-field light components. This mini-review provides a perspective on recent progress and emerging directions aimed at utilizing and controlling in-plane optical polarization, highlighting key application spaces where in-plane near-field tip responses have enabled recent advancements in the understanding and development of new nanostructured materials and devices.