The degree of spectral coherence characterizes the spectral purity of light. It can be equivalently expressed in the time domain by the decay time τ or the quality factor Q of the light-emitting oscillator, the coherence time τ coh or length λcoh of emitted light or, via Fourier transformation to the frequency domain, the linewidth Δν of emitted light. We quantify these parameters for the reference

In this paper we review the field of terahertz (THz) sources which make use of the nonlinear, stimulated polariton scattering (SPS) process. A historical perspective of the technology is offered, in addition to an investigation of modern SPS-based THz sources. Breakthroughs in these source technologies have coincided with rapid developments in laser technology over the past 10 years. We are now in

Blue LEDs and HEMTs based on III-Nitride have been flourishing commercially across the globe, thanks largely to breakthroughs in the material quality of the wide-bandgap compound semiconductor back in the 1990s. The realizations of white-light LEDs, blu-ray systems, and lately efficient compact chargers have drastically changed the way we live and have contributed tremendously to global energy saving

This paper reviews the field of microwave photonics instantaneous frequency measurements (IFM). It aims to consolidate the literature, explains the key implementations and reviews the recent developments. Current photonic IFMs are capable of operating over a wide bandwidth with a good resolution. However, their implementations are often based on discrete components and exhibit limited dynamic range

The development of the HgCdTe alloy as the most important intrinsic semiconductor for infrared (IR) technology is well established and recognized. In spite of the achievements in material and device quality, the drawbacks still exist due to bulk and surface instability, lower yields and higher costs particularly in fabrication of long wavelength infrared arrays. The difficulties with this material

Cr: Colquiriite laser materials (Cr:LiCAF, Cr:LiSAF, Cr:LiSGaF) own broad absorption bands in the visible region that allow direct-diode pumping by well-developed low-cost red diodes. Moreover, they possess broad emission bands in the near infrared that enable widely tunable laser operation (720–1110 nm), and generation of sub-10-fs light pulses via mode-locking. Furthermore, Cr: Colquiriite crystals

Recent advances in the development of quantum dots (QDs) have offered new possibilities for the exploration of sensors, bio imaging, batteries, electrochemical water splitting and optoelectronic applications because of their intriguing optical, electrical, catalytic and electrochemical properties. Among QDs, atomically thin two-dimensional quantum dots (2D QDs) derived from graphene sheets, transition

Visible wavelength light-emitting diodes (LEDs) and laser diodes (LDs) enabled optical wireless communication (OWC) is an emerging technology for realizing high-confidentiality and high-speed point-to-point (PtP), vehicle-to-vehicle, and white-lighting data access links in indoor/outdoor free-space and underwater environments. Notably, OWC facilitates users to access more transmission bandwidth and

Development of Si photonic integrated circuits (PICs) has been impeded due to lack of efficient Si-based light-emitting sources. Because of their indirect bandgap, bulk Ge and Si are very inefficient at emitting light. Therefore, direct-bandgap III-V semiconductors have been extensively exploited for the active region of the lasers for PICs. Heterogeneous and monolithic integration of III-V semiconductor

Electromagnetic (EM) metamaterials are artificially engineered media composed of subwavelength unit cells, which achieve exotic EM properties beyond the limits of natural materials and provide great freedom to manipulate EM waves. Here, we review the recent progress on metamaterials in terms of three aspects: effective medium metamaterials, plasmonic metamaterials, and information metamaterials, respectively

Plasmons, the electromagnetic excitations coupled with electron waves, possess the intrinsic ability of manipulating light at subwavelength scales down to picometer. This ability not only helps uncovering the fascinating quantum behaviors that strengthen the basic understanding of quantum science, but also enables the inventions of various quantum optoelectronic devices, triggering the birth of quantum

The optical microresonators reviewed in this paper are called bottle microresonators because their profile often resembles an elongated spheroid or a microscopic bottle. These resonators are commonly fabricated from an optical fiber by variation of its radius. Generally, variation of the bottle microresonator (BMR) radius along the fiber axis can be quite complex presenting, e.g., a series of coupled

The applications of light absorbers concern photodetectors, optical filters, solar applications or flexible electronics. In this review, we will detail the application of such light absorbers and we will develop the main demonstrations of the use of metallic nanoparticles embedded within a host matrix to fabricate coatings aiming at harvesting light. We will explain how chemically synthetized silver

In this review, we describe dielectric properties of biological tissues and liquids in the context of terahertz (THz) biophotonics. We discuss a model of the THz dielectric permittivity of water and water-containing media, which yields analysis of the relaxation and damped resonant molecules modes. We briefly describe modern techniques of THz spectroscopy and imaging employed in biophotonics with a

Intriguing intrinsic properties of light quanta and related topics are reviewed by emphasizing the self-consistency of light-matter interactions and open nano-systems dynamics. It is pointed out that there still remain fundamental and challenging issues related to quantization of a finite nano-system interacting with a massive (i.e., localized) photon field,as well as with a hierarchical or structured

Since the first observation of stimulated emission from colloidal quantum dots (CQDs) in year 2000, tremendous progress has been made in developing solution-processed lasers from colloidal semiconductor nanostructures in terms of both understanding the fundamental physics and improving the device performance. In this review paper, we will start with a brief introduction about the fabrication of CQDs

Ideal integrated light emitters for optical interconnects should be compact in size, high in modulation bandwidth, efficient in energy consumption and tunable in frequency. Nanolasers are excellent candidates for such an application. In this article, we review and offer further in-depth analyses in three key aspects of recent nanolaser research, including second order intensity correlation, g2(τ),

Combustion is one of the most dominant energy conversion processes used in all areas of human life, but global concerns over exhaust gas pollution and greenhouse gas emission have stimulated further development of the process. Lean combustion and exhaust gas recirculation are approaches to improve the efficiency and to reduce pollutant emissions; however, such measures impede reliable ignition when

GaN is a great material for making optoelectronic devices in the blue, blue-violet and green bands. Vertical-cavity surface-emitting lasers (VCSELs) have many advantages including small footprint, circular symmetry of output beam, two-dimensional scalability and/or addressability, surface-mount packaging, good price-performance ratio, and simple optics/alignment for output coupling. In this paper,

For over half a century, laser technology has undergone a technological revolution. These technologies, particularly semiconductor lasers, are employed in a myriad of fields. Optical medical diagnostics, one of the emerging areas of laser application, are on the forefront of application around the world. Optical methods of non- or minimally invasive bio-tissue investigation offer significant advantages

This article reviews recent progress in theoretical studies of dressed photons. For providing concrete physical images of dressed photons, several experimental studies are demonstrated. They are applications of dressed photons to novel optical functional devices, nano-fabrication technologies, energy conversion technologies, and photon breeding devices. After these experimental demonstrations, as the

The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research

We review recent research on nonlinear optical interactions in optical-fiber nanowires (OFNs) with sub-micron transverse dimensions. Such OFNs, which are fabricated from standard optical fibers, offer numerous beneficial optical and mechanical properties, including strong evanescent fields, high flexibility and configurability, a small mass, and low-loss interconnection to other optical fibers and

Sir Peter Knight is a pioneer in quantum optics which has now grown to an important branch of modern physics to study the foundations and applications of quantum physics. He is leading an effort to develop new technologies from quantum mechanics. In this collection of essays, we recall the time we were working with him as a postdoc or a PhD student and look at how the time with him has influenced our

Optical Coherent Multidimensional Spectroscopy (CMDS) has been developed to probe the electronic states of a diverse range of complex systems. The great advantage of CMDS over linear spectroscopy is the ability to separate and quantify different types of interactions. To do this, multiple carefully controlled femtosecond laser pulses drive a non-linear response in the sample. A specific component of

The lack of wireless spectrum in the radio frequency bands has led to a rapid growth in research in wireless networking using light, known as LiFi (light fidelity). In this paper an overview of the subsystems, challenges and techniques required to achieve this is presented.

Quantum optics is the study of the intrinsically quantum properties of light. During the second part of the 20th century experimental and theoretical progress developed together; nowadays quantum optics provides a testbed of many fundamental aspects of quantum mechanics such as coherence and quantum entanglement. Quantum optics helped trigger, both directly and indirectly, the birth of quantum technologies

Interaction between light and materials is essential in the physics underlying all optical devices, including light emitting devices such as light emitting diodes and lasers, photo-voltaic devices, and photo-synthesis systems. The demand for higher light utilization efficiency is becoming increasingly important for advanced optical devices. This is because, when feature size is smaller than the incident

Perovskite solar cell research has been attracting increasing attention in recent years. In this review paper, we will provide an overview of the recent developments in terms of material composition, deposition techniques, and the device architecture (the choice of charge transport layers and electrodes). Then, we will critically discuss some of the major problems, namely device stability, hysteresis

The distributed quantum network, in which nodes comprising small but well-controlled quantum states are entangled via photonic channels, has in recent years emerged as a strategy for delivering a range of quantum technologies including secure communications, enhanced sensing and scalable quantum computing. Colour centres in diamond are amongst the most promising candidates for nodes fabricated in the

For over 55 years, laser technology has expanded from laboratory research to widespread fields, for example telecommunication and data storage amongst others. Recently application of lasers in biology and medicine presents itself as one of the emerging areas. In this review, we will outline the recent advances in using lasers for the generation of singlet oxygen, traditionally used to kill tumour cells

The essential functionality of photonic and electronic devices is contained in thin surface layers leaving the substrate often to play primarily a mechanical role. Layer transfer of optimised devices or materials and their heterogeneous integration is thus a very attractive strategy to realise high performance, low-cost circuits for a wide variety of new applications. Additionally, new device configurations

This paper will review the coupling by stimulated Raman scattering between two laser fields and its dependence on the spectral properties of those fields. We describe the coupling in terms of an effective Raman gain that depends on the fields’ linewidths, the material dispersion, and specific experimental conditions. The aim is to provide an intuitive understanding of this behaviour, by presenting

Adhesion is a critical cellular process that contributes to migration, apoptosis, differentiation, and division. It is followed by the redistribution of cellular materials at the cell membrane or at the cell-surface interface for cells interacting with surfaces, such as basement membranes. Dynamic and quantitative tracking of changes in cell adhesion mass redistribution is challenging because cells

Photon management is essential in improving the performances of optoelectronic devices including light emitting diodes, solar cells and photo detectors. Beyond the advances in material growth and device structure design, photon management via nanoscaled phenomena have also been demonstrated as a promising way for further modifying/improving the device performance. The accomplishments achieved by photon

The interest in Infrared and Ultraviolet detectors has increased immensely due to the emergence of important applications over a wide range of activities. Detectors based on free carrier absorption known as Hetero-junction Interfacial Workfunction Internal Photoemission (HEIWIP) detectors and variations of these heterojunction structures to be used as intervalence band detectors for a wide wavelength

In the last decade, new strategies to achieve high-operating temperature (HOT) detectors have been proposed, including barrier structures such as nBn devices, unipolar barrier photodiodes, and multistage (cascade) infrared detectors. The ability to tune the positions of the conduction and valence band edges independently in a broken-gap type-II superlattices is especially helpful in the design of unipolar

The field of optically pumped planar waveguide lasers has seen a rapid development over the last two decades driven by the requirements of a range of applications. This sustained research effort has led to the demonstration of a large variety of miniature highly efficient laser sources by combining different gain media and resonator geometries. One of the most attractive features of waveguide lasers

Group-III nitride nanowire structures, including GaN, InN, AlN and their alloys, have been intensively studied in the past decade. Unique to this material system is that its energy bandgap can be tuned from the deep ultraviolet (~6.2 eV for AlN) to the near infrared (~0.65 eV for InN). In this article, we provide an overview on the recent progress made in III-nitride nanowire optoelectronic devices

Optical signal processing has long been recognized as a promising route to a new class of fast and energy efficient devices. The former parameter, the speed, has indeed been addressed in a number of different signal processing roles, confirming the superiority of optical signal processing devices with respect to their electronic counterpart. After gaining some maturity, the field has now advanced to

Tunable single mode pulsed dye lasers are capable of generating optical radiations in the visible range having very small bandwidths (transform limited), high average power (a few kW) at a high pulse repetition rate (a few tens of kHz), small beam divergence and relatively higher efficiencies. These dye lasers are generally utilized laser dyes dissolved in solvents such as water, heavy water, ethanol

Recent developments in laser sources operating in the mid-IR (3–8μm) have been motivated by the numerous possibilities for both fundamental and applied research. One example is the ability to unambiguously detect pollutants and carcinogens due to the much larger oscillator strengths of their absorption features in the mid-IR spectral region compared with the visible. Broadband sources are of particular

The development of parametric devices down-converting the laser frequency to the mid-infrared (3–30 µm) based on non-oxide nonlinear optical crystals is reviewed. Such devices, pumped by solid-state laser systems operating in the near-infrared, fill in this spectral gap where no such lasers exist, on practically all time scales, from continuous-wave to femtosecond regime. All important results obtained

Controlling light interactions with matter on the nanometer scale provides for compelling opportunities for modern technology and stretches our understanding and exploitation of applied physics, electronics, and fabrication science. The smallest size to which light can be confined using standard optical elements such as lenses and mirrors is limited by diffraction. Plasmonic nanostructures have the

A review of authors’ contributions to dye-doped cholesteric liquid crystal (CLC) lasers started from the pioneer authors’ paper of 1980 in which the experimental realization of the first CLC laser is presented. Both distributed feedback (DFB) and photonics band edge lasing models are discussed for different experimental conditions. A detailed study and analysis of basic characteristics of steroidal

Spectrum-splitting photovoltaics is an alternative to multi-junction tandem cells which has been the subject of renewed interest in recent years as researchers try to push the limits of efficiency and cost-reduction for solar energy production. A myriad of solutions have been proposed for the spectrum-splitting optics, yet the basic cell technologies for these systems have received comparatively little

Plasmonic quasicrystals consisting of quasi-periodic metal–dielectric patterns offer several advantages compared to the periodic patterns or plasmonic crystals. This paper reviews the present status in theoretical design, modeling, fabrication and basic and applied results on plasmonic quasicrystals. In addition to the current status, possible future prospects of plasmonic quasicrystals are also discussed

This review aims at providing a comprehensive and updated picture of the field of hyperbolic metamaterials, from the foundations to the most recent progresses and future perspectives. The topics discussed embrace theoretical aspects, practical realization and key challenges for applications such as imaging, spontaneous emission engineering, thermal, active and tunable hyperbolic media.

The advances in lasers, electronic and photonic integrated circuits (EPIC), optical interconnects as well as the modulation techniques allow the present day society to embrace the convenience of broadband, high speed internet and mobile network connectivity. However, the steep increase in energy demand and bandwidth requirement calls for further innovation in ultra-compact EPIC technologies. In the

Mid-infrared (mid-IR) supercontinuum (SC) sources have recently gained much interest, as a key technology for such applications as spectral molecular fingerprinting, laser surgery, and infrared counter measures. However, one of the challenges facing this technology is how to obtain high power and broadband light covering a spectral band of at least 2–5 µm, especially with a very efficient output power

We report on recent progress in the generation of non-diffracting (Bessel) beams from semiconductor light sources including both edge-emitting and surface-emitting semiconductor lasers as well as light-emitting diodes (LEDs). Bessel beams at the power level of Watts with central lobe diameters of a few to tens of micrometers were achieved from compact and highly efficient lasers. The practicality of

Ripples are formed on the surface of solid materials after interaction with laser pulses of high intensity/irradiance. When ultra-short sub-1 ps laser pulses are used, the observed morphology of ripples on surfaces becomes much more complex as compared with ripples formed by long laser pulses. Uniquely for the short laser pulses, ripples can be formed in the bulk. A better understanding of the fundamentals

Nematic liquid crystals possess large and versatile optical nonlinearities suitable for photonics applications spanning the femtoseconds to milliseconds time scales, and across a wide spectral window. We present a comprehensive review of the physical properties and mechanisms that underlie these multiple time scales nonlinearities, delving into individual molecular electronic responses as well as collective

In contrast to a conventional symmetric Lorentzian resonance, Fano resonance is predominantly used to describe asymmetric-shaped resonances, which arise from the constructive and destructive interference of discrete resonance states with broadband continuum states. This phenomenon and the underlying mechanisms, being common and ubiquitous in many realms of physical sciences, can be found in a wide

Over the last decade, significant advances have been made toward the development of practical, tunable solid state dye lasers, which resulted in improved lasing efficiency with reduced dye photodegradation. To achieve this goal, a “chemical” approach was followed, where attention was focused onto the particular dye/host interaction and compatibility, specifically choosing already existing hosts for

Optics originally developed for tunable organic dye lasers have found applications in other areas of optics, laser optics, and quantum optics. Here, the salient aspects of the physics related to the cavity linewidth equation and the effects of intracavity beam expansion and intracavity dispersion on this equation are reviewed. Additionally, the generalized multiple-prism dispersion equation is applied

This review encompasses ultrafast laser interaction with matter in a broad range of intensities ~1010–1015 W/cm2. We consider the material transformation processes successively with increase of the absorbed laser intensity. We start with the subtle atomic displacements and excitation of phonons, and further analyze the phase transitions, ablation, transformation into plasma, and interaction of laser

This paper describes and discusses visible fiber lasers that are excited by GaN laser diodes. One of the attractive points of visible light is that the human eye is sensitive to it between 400 and 700 nm, and therefore we can see applications in display technology. Of course, many other applications exist. First, we briefly review previously developed visible lasers in the gas, liquid, and solid-state

The progression of carrier confinement from quantum wells to quantum dots has received considerable interests because of the potential to improve the semiconductor laser performance at the underlying physics level and to explore quantum optical phenomena in semiconductors. Associated with the transition from quantum wells to quantum dots is a switch from a solid-state-like quasi-continuous density