Possibility Of Photons Research Articles

InSb-based saturable absorbers for ultrafast photonic applications.

Sb-related III-V compounds have recently gained great research interest owing to their excellent optical and electrical characteristics, which provide many possibilities in photonics and electronics. This study investigated the application of InSb films in ultrafast photonics. An InSb film was fabricated on the tapered zone of a microfiber, and its saturation intensity, modulation depth, and non-saturable loss were determined as 119.8 MW cm-2, 23.5%, and 27.3%, respectively. The structure of the electronic band and density of states of InSb were theoretically calculated. Notably, mode-locked and Q-switched fiber lasers were realised by incorporating the InSb-microfiber device into two different Er-doped fiber cavities. In the Q-switching state, the narrowest pulse duration was measured as 1.756 μs with a maximum single-pulse energy of 221.95 nJ and a signal-to-noise ratio of 60 dB. In the mode-locking operation, ultrafast lasers with a high signal-to-noise ratio (70 dB), a pulse width as narrow as 265 fs and a repetition rate of 49.51 MHz were acquired. Besides, the second-harmonic mode-locked state was built with an output power of 13.22 mW. In comparison with the reported laser performance with 2D materials as saturable absorbers, the InSb-based mode-locked and Q-switched fiber lasers proposed herein exhibit better comprehensive performance.

MXene Saturable Absorbers in Mode‐Locked Fiber Laser

AbstractBeing a new class of two dimensional (2D) metal carbides, borides, and nitrides, MXenes comprise one of the largest families of 2D nanomaterials that provide huge possibilities in photonics, electronics, and energy, Particularly, MXenes are discovered recently as alternatives to conventional saturable absorbers (SAs), such as carbon nanotube and graphene, which are used for short laser pulse generation. The high saturable absorption, astounding modulation depth, flexible bandgap tunability, and high electron density near Fermi level are the main features that make MXenes excellent candidate materials for SAs. Herein, this review summarizes the recent development on synthesis and characterization of the MXene, with focus on the nonlinear saturable absorption and the application of the MXene SA in mode‐locked fiber lasers. The emerging issues and challenges associated with MXene based SAs, as well as future perspectives of the reviewed topic are also discussed.

Оценка возможности использования фотонного движителя для поддержания орбиты малого космического аппарата

Оценка возможности использования фотонного движителя для поддержания орбиты малого космического аппарата

Improved Light Extraction of GaN-based LED with Patterned Ga-doped ZnO Transparent Conducting Layer

ABSTRACTIn this study, patterned Ga-doped ZnO transparent conducting layers were made to increase the light-extraction efficiency of GaN-based LEDs. The patterns were designed by different side length, spacing and depth of the concave squares. Simulations and experiments were taken to study the light output powers of LEDs made by patterned transparent conducting layers. The area of the vertical sidewalls of the patterns is thought to have important effect on the light extraction of LEDs. With bigger sidewalls, the escape possibility of photon can be increased. Compared with conventional LEDs with planar Ga-doped ZnO transparent conducting layers, the light output power can be increased by 8.9% via using 10μm side length, 5μm spacing and 400 nm depth concave square patterns, which is basically consistent with the simulated results.

TaCoNa-Photonics 2008

This special section on theoretical and computational nano-photonics features papers presented at the first International Workshop on Theoretical and Computational Nano-Photonics (TaCoNa-Photonics 2008) held in Bad Honnef, Germany, 3–5 December 2008. The workshop covered a broad range of topics related to current developments and achievements in this interdisciplinary area of research. Since the late 1960s, the word `photonics' has been understood as the science of generating, controlling, and detecting light. Nowadays, a routine fabrication of complex structures with micro- and nano-scale dimensions opens up many new and exciting possibilities in photonics. The science of generating, routing and detecting light in micro- and nano-structured matter, `nano-photonics', is becoming more important both in research and technology and offers many promising applications. The inherently sub-wavelength character of the structures that nano-photonics deals with challenges modern theoretical and computational physics and engineering with many nontrivial questions: Up to what length-scale can one use a macroscopic phenomenological description of matter? Where is the interface between the classical and quantum description of light in nano-scale structures? How can one combine different physical systems, different time- and length-scales in a single computational model? How can one engineer nano-structured materials in order to achieve the desired optical properties for particular applications? Any attempt at answering these kinds of questions is impossible without the joint efforts of physicists, engineers, applied mathematicians and programmers. This is the reason why the major goal of the TaCoNa-Photonics workshops is to provide a forum where theoreticians and specialists in numerical methods from all branches of physics, engineering sciences and mathematics can compare their results, report on novel results and breakthroughs, and discuss new challenges ahead. In order to intensify theoretical discussions and to put them on `solid' ground it was decided to invite world-leading experts in experimental photonics for plenary talks. Over three days, the workshop has brought together more than 70 specialists in theoretical and computational nano-photonics. The workshop took place in the historical `Physikzentrum Bad Honnef', whose unique atmosphere supported a multitude of highly interesting debates and discussions that often lasted until midnight and beyond. Different theoretical and numerical aspects of light generation, control and detection in general inhomogeneous media, photonic crystals, plasmonic structures, metamaterials and integrated optical systems were covered in 15 invited talks and 52 contributed oral and posters presentations. The plenary talks were given by Professor M Wegener (metamaterials) and Professor W Barnes (plasmonics). This special section is a cross-sectional selection of papers which were submitted by the authors of invited and contributed oral presentations. It also includes two papers of the winners of the Best Poster Awards. We hope that these papers will enhance the interest of the scientific community regarding nano-photonics in general and regarding the TaCoNa-Photonics workshop series in particular. It is our distinct pleasure to acknowledge the generous financial support of our sponsors: Karlsruhe School of Optics & Photonics (KSOP) (Germany), U.S. Army International Technology Center-Atlantic, Research Division (USA), and the Office of Naval Research Global (USA). Without the organizational assistance from the International Department of the Universitat Karlsruhe GmbH (Germany) this event would simply have been impossible.

Narrow-Bandwidth Spontaneous Luminescence from Oriented Semiconducting Polymer Nanostructures

High-resolution fluorescence imaging of isolated nanoparticles of a common semiconducting polymer (poly[2-methoxy-5-(2‘-ethyl-hexyloxy)-1,4-phenylene vinylene, MEH-PPV), produced by ink-jet printing techniques, has revealed highly uniform transition moment orientation perpendicular to the glass substrate. In contrast with the broad emission spectra associated with bulk or single molecules of these species in thin films, we observe narrow photoluminescence emission spectra (10−15 nm fwhm) from individual oriented polymer nanostructures with no evidence of spectral diffusion on time scales of several hundred seconds. The distribution of center frequencies (from several hundred individual nanoparticle measurements) shows clearly defined peaks that can be correlated with excitonic traps of integer multiples of monomer conjugation lengths (8, 9, 10, and 11). The observation of discrete emission characteristics in this important class of materials suggests exciting possibilities in photonics and molecular optoe...

The diffraction mechanism of electron-positron pair photoproduction

We examine a mechanism of electron-positron pair photoproduction near a giant resonance. The mechanism is based on the possibility of photons being absorbed by nuclei. Our calculations set the cross section of this process at roughly 10−30 cm2. We also discuss the feasibility of observing the effect.

Manipulation of photons in a cavity by dispersive atom-field coupling: Quantum-nondemolition measurements and generation of "Schrödinger cat" states.

A quantum-nondemolition method to measure the number of photons stored in a high-Q cavity, introduced by Brune et al. [Phys. Rev. Lett. 65, 976 (1990)], is described in detail. It is based on the detection of the dispersive phase shift produced by the field on the wave function of nonresonant atoms crossing the cavity. This shift can be measured by atomic interferometry, using the Ramsey separated-oscillatory-field method. The information acquired by detecting a sequence of atoms modifies the field step by step, until it eventually collapses into a Fock state. At the same time, the field phase undergoes a diffusive process as a result of the back action of the measurement on the photon-number conjugate variable. Once a Fock state has been generated, its evolution under weak perturbation can be continuously monitored, revealing quantum jumps between various photon numbers. When applied to an initial coherent field, the intermediate steps of the measuring sequence produce quantum superpositions of classical fields, known as ``Schr\"odinger cat states.'' Ways to prepare and detect these states in a cavity subjected to a weak relaxation process are discussed. The effects analyzed in this article could realistically be observed by using circular Rydberg atoms and very high-Q superconducting microwave cavities. The possibility of photon ``manipulation'' through nonresonant atom-field interactions opens a domain in cavity QED studies.