All Optical Devices

The function that we know about the use of light and materials is the 3rd century of the 4th millennium BC. At that time light and material to be used to create a surface difference in the level of the external walls in order to obtain light and shade. The amount of light on color and sound that we need differs in different spaces and depends on the type of use of the space and its functions. Some spaces are probably used during the day or only at night and some architecture used both in day and night. Therefore, these issues should be taken into consideration when choosing the materials and its features to use light on color, sound and water for the desired space. Many principles are effective in designing light on color and sound in nowadays architecture and materials and one of them is the principle of surface difference and the existence of levels of perceptions of light on color and sound that were used to absorb and reflect, refract and diffract of light on color and sound into the space of the architecture. By conducting experiments, Ibn Haytham investigates the movement of light in environments and materials with different transparencies and based on that, he considers the size of the angle of refraction or the amount of refraction of light in different environments and materials to be related to the size of the angle of reflection or the angle of radiation. Suhrawardi says that light is something that is in fact the manifestation of its own self and the manifestation of other beings. Suhrawardi also emphasizes in the definition of light that light is that which has manifested itself in its true nature and is the cause of the appearance of others, because Appearance is inherent to light, so light is more visible than all other things, whose appearance is temporary. The question of article is based on Ibn Haytham and how light and materials cause surface difference?

The function that we know about the use of light and materials is the 3rd century of the 4th millennium BC. At that time light and material to be used to create a surface difference in the level of the external walls in order to obtain light and shade.
The amount of light on color and sound that we need differs in different spaces and depends on the type of use of the space and its functions. Some spaces are probably used during the day or only at night and some architecture used both in day and night. Therefore, these issues should be taken into consideration when choosing the materials and its features to use light on color, sound and water for the desired space.
Many principles are effective in designing light on color and sound in nowadays architecture and materials and one of them is the principle of surface difference and the existence of levels of perceptions of light on color and sound that were used to absorb and reflect, refract and diffract of light on color and sound into the space of the architecture.
By conducting experiments, Ibn Haytham investigates the movement of light in environments and materials with different transparencies and based on that, he considers the size of the angle of refraction or the amount of refraction of light in different environments and materials to be related to the size of the angle of reflection or the angle of radiation.
Suhrawardi says that light is something that is in fact the manifestation of its own self and the manifestation of other beings. Suhrawardi also emphasizes in the definition of light that light is that which has manifested itself in its true nature and is the cause of the appearance of others, because Appearance is inherent to light, so light is more visible than all other things, whose appearance is temporary.
The question of article is based on Ibn Haytham and how light and materials cause surface difference?

In this paper we show two approaches to fabricate photonic channels on different substrate technology platforms, in particular silicon and polydimethylsiloxane (PDMS), for flexible photonic integrated circuits. The electro-optic effect and nonlinear optical properties of liquid crystals (LC) allow the realization of low cost and low energy consumption optoelectronic devices operating at both visible and near-infrared wavelengths. High extinction ratio and large tuning range guided wave devices will be presented to be used for both optofluidic and datacom applications, in which both low realization costs and low power consumption are key features. In particular we will show our recent results on polarization independent light propagation in waveguides whose core consists of LC infiltrated in PDMS channels (LC:PDMS waveguides) fully compatible with optofluidic and lab-on-chip microsystems.

160 Gb/s All-Optical Contention Resolution with Prioritization using Integrated Photonic Components P. Bakopoulos (1), P. Zakynthinos (1), E. Kehayas (1), L. Stampoulidis (1), F. Fresi (3), C. Porzi (3), N. Calabretta (5), Ch. Kouloumentas (1), D. Petrantonakis (1), A. Maziotis (1), C. Stamatiadis (1), D. Apostolopoulos (1), M. Guina (4), D. Klonidis (7), L. Potì (2), E. Tangdiongga (5), A. Poustie (6), G. Maxwell (6), I. Tomkos (7), A. Bogoni (2), HJS Dorren (5) and H. Avramopoulos (1) 1 : National Technical University of Athens – School of Electrical and Computer Engineering ...

In this study, a novel, two-dimensional photonic crystal-based structure for the 2-to-4 optical decoder is presented. The structure consists of 23 rows and 14 columns of chalcogenide rods that are arranged in a square lattice with a spatial periodicity of 530 nm. The bias and the optical signals are guided toward the main waveguide through the three waveguides. Two unequal powers are applied to the input ports to approach the different intensities proportional to four working states into the main waveguide. Four cavities including the nonlinear rods are in response to drop the optical waves toward the output ports. To calculate the band diagram and the spatial distribution of the electric and magnetic fields, the plane wave expansion and the finite difference time domain methods have been used. The delay time of the designed structure is obtained around 220 fs, which is less than one for the previous structures. Furthermore, the gap between the margins for logic 0 and 1 is equal to ...

In this review, a comprehensive summary on photonic crystal based all-optical logic decoder reported in the last decade has been made. The articles reviewed are primarily grouped into two broad tributaries based on linear and nonlinear regimes of optical interactions inside photonic crystal structures. The reasons behind choosing PhC structures are because of their excellent abilities to control and guide the flow of optical signal along with the intense light-matter interaction in sub-wavelength scale, which have been utilized substantially to realize decoder circuits. Each group of the articles has been analysed extensively, and their prospective merits and demerits are discussed in terms of different performance metrics such as operating speed, requirement of power, footprint, contrast ratio between output logic levels etc. The review concludes while focusing on prospective discussions on the issues for further advancements in this field based on different techniques.

We examine the response of a pulse pumped quantum dot laser both experimentally and numerically. As the maximum of the pump pulse comes closer to the excited-state threshold, the output pulse shape becomes unstable and leads to dropouts. We conjecture that these instabilities result from an increase of the linewidth enhancement factor α as the pump parameter comes close to the excitated state threshold. In order to analyze the dynamical mechanism of the dropout, we consider two cases for which the laser exhibits either a jump to a different single mode or a jump to fast intensity oscillations. The origin of these two instabilities is clarified by a combined analytical and numerical bifurcation diagram of the steady state intensity modes.

How does the quantum-to-classical transition of measurement occur? This question is vital for both foundations and applications of quantum mechanics. Here, we develop a new measurement-based framework for characterizing the classical and quantum free electron–photon interactions and then experimentally test it. We first analyze the transition from projective to weak measurement in generic light–matter interactions and show that any classical electron-laser-beam interaction can be represented as an outcome of weak measurement. In particular, the appearance of classical point-particle acceleration is an example of an amplified weak value resulting from weak measurement. A universal factor, $$\exp \left(-{\Gamma }^{2}/2\right)$$ exp − Γ 2 / 2 , quantifies the measurement regimes and their transition from quantum to classical, where $$\Gamma$$ Γ corresponds to the ratio between the electron wavepacket size and the optical wavelength. This measurement-based formulation is experimentally ...

Sunlight contamination dominates the backscatter noise in space-based lidar measurements during daytime. The background scattered sunlight is highly variable and dependent upon the surface and atmospheric albedo. The scattered sunlight contribution to noise increases over land and snow surfaces where surface albedos are high and thus overwhelm lidar backscatter from optically thin atmospheric constituents like aerosols and thin clouds. In this work, we developed a novel lidar remote sensing concept that potentially can eliminate sunlight induced noise. The new lidar concept requires: (1) a transmitted laser light that carries orbital angular momentum (OAM); and (2) a photon sieve (PS) diffractive filter that separates scattered sunlight from laser light backscattered from the atmosphere, ocean and solid surfaces. The method is based on numerical modeling of the focusing of Laguerre-Gaussian (LG) laser beam and plane-wave light by a PS. The model results show that after passing throu...

Novel imaging techniques utilizing nondegenerate, correlated photon pairs sparked intense interest during the last couple of years among scientists of the quantum optics community and beyond. It is a key property of such ''ghost imaging'' or ''quantum interference'' methods that they use those photons of the correlated pairs for imaging that never interacted with the sample, allowing detection in a spectral range different from that of the illumination of the object. Extensive applications of these techniques in spectroscopy and microscopy are envisioned, however, their limited spatial resolution to date has not yet supported real-life microscopic investigations of tiny biological objects. Here we report a modification of the method based on quantum interference by using a seeding laser and confocal scanning, that allows the improvement of the resolution of imaging with undetected photons by more than an order of magnitude, and we also present examples of application in the microscopy of biological samples. INDEX TERMS Biological application, quantum entanglement, scanning interferometric microscopy.

In this paper microring resonator based logic gates are discussed that operate on same input and output wavelength. Same input and output wavelength allows the cascaded operation of the developed logic gates and thus can be utilized for developing photonic integrated circuits. Logic operations such as AND, OR, NOR, XOR and XNOR are successfully demonstrated. Optical Kerr effect is utilized for operation and structures are numerically simulated using coupled mode equations. Output power levels of around 0.18 W and 0.05 W are achieved for high and low power logic respectively. The proposed structures perform well for data rate under 1 Gbps and are analysed to determine the acceptable input range for high and low power logic respectively. The cascaded operation of proposed logic gates is also demonstrated.

DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

We construct proper microscopic propositions to consistently explain the interference patterns obtained for electrons and photons in well-defined one-and two-slit experiments. Our propositions are also made explicit on the basis of quantum mechanics with proper quantitative analysis to support the correctness of the physical mechanisms proposed herein, which obey the wave-particle duality. Apart from that, the microscopic propositions constructed herein can be treated as guidelines in setting up the future experiments such that one can unambiguously support or oppose this strange notion-a quantum particle behaves differently depending upon the number of slit, and where we place the detector such that the particle can sense the detector and the number of slit, before physically interacting with them.

An optimized all-optical "NAND" logic gate is studied analytically. The particular characteristic of this logic gate is that it is based on photonic crystals, it consists of a resonator coupled with two waveguides on a silicon substrate. The operating wavelength is equal to 1.55µm which represents the telecommunication wavelength, the switching power of the optical logic gate studied is 1.693 kw /µm2 its response is independent of the response of the resonator when the power intensity of the optical waves is lower than the resonance wavelength, the light will be coupled in the waveguides, in the opposite case the light propagates in the waveguide of the bus.

We propose a novel designed structure which is a demultiplexer of 2D square photonic crystal of circular rods embedded in air that have locally three cavities with different sizes, refractive indexes, and also appropriately sized adjacent rods. Firstly, for one constant refractive index n (n = 3.3763) and with individual radius for each cavity and their adjacent rods, we have three different output resonant wavelengths; it means that this structure drops the desired wavelength depending on the geometric parameters. We have optimized this structure by varying locally the refractive index for each of the resonant cavity. In this case, we have obtained in one structure i.e. a single refractive index for all the structures except the cavities of course, three different zones with specific geometric and physical properties. As a result, three wavelengths have been extracted from these cavities. The corresponding optical transmission powers and Q factors are T1 = 83.54%, T2 = 100%, T3 = 81.97%, and Q1 = 2690.3, Q2 = 3248.8, Q3 = 8212.5, respectively. By changing both the size and refractive index of the cavity and the size of their adjacent rods, the structure is able to drop the desired wavelength, and the tunability property is achieved.

Wavelength conversion employing semiconductor optical amplifiers (SOAs) is currently one of the most attractive and promising wavelength conversion techniques for future all-optical systems. This paper investigates the comparative performances of the three most popular SOA wavelength conversion techniques; cross-gain modulation (XGM), cross-phase modulation (XPM) and four-wave mixing (FWM). The FWM wavelength converter is analyzed for two types of source; a CW and a novel spectrum-sliced source. All performances are analyzed in terms of shifted wavelength conversion efficiency, Q-factors and converted signal powers. The converters are modeled and simulated using OptSim software. It was found that XGM yields the highest conversion efficiency of 17 dB, followed by XPM having 9 dB. The FWM wavelength converter had the lowest conversion efficiency, around-0.7 dB and-5.0 dB for CW and spectrum-sliced sources respectively.

High average gains of greater than 31 dB have been obtained between 1530-1560 nm (conventional-wavelength band, C-band) and 1570-1600 nm (long-wavelength band, L-band) using a saturating tone technique that represents 64 channels of a wavelength division multiplexed system. A bidirectional amplifying stage is utilized as high-power C-band and low-noise L-band stages. Noise figures of less than 3.6 and 5.4 dB are measured for the C-and L-bands, respectively.

The article aims to reflect on the sensory impact of colour in chromo-luminous projections made by futurist Italian artists Arnaldo Ginna and Bruno Corra. A wide range of studies situated these experiments of chromatic music in continuity with the tradition of synesthetic devices, which, starting from Castel’s ocular harpsichord, focused on the equivalence between music and luminous féeries. Scholars also insisted on a relationship with psychological theories, paying attention to the psychological function of projected colours as signs of certain moods. However, the influence of the psychophysiology of color on Ginna’s and Corra’s animated paintings needs to be investigated more deeply. Starting from the connection between experimental psychology and avant-garde experiences, the essay seeks to discuss the practices and devices based on chromatic suggestion, which were used as therapeutic tools in the medical field, and the way in which the futurist chromo-luminous projections utilized these practices to condition the spectator. In Ginna’s and Corra’s experiments and writings, indeed, colour was conceived as a suggestive medium. The notion of suggestion (“A.B.C. Metodo”, 1910) was specifically borrowed from nineteenth century medical terminology (Charcot, Bernheim, etc.) and was popularized in Italy by Giulio Belfiore. This notion permitted Ginna and Corra to elaborate upon an experimental method meant to fascinate the spectator. In some ways, these visual experiments aspired to replicate suggestive practices typical of hypnotism, which used colour for its power to condition the mind. Various devices were adopted in psychological laboratories in order to induce hypnotic or suggestive reactions: rotating discs, coloured lights, magic lantern projections, chromatropes, etc. Therefore, Ginna and Corra used colour in the same experimental manner. As in psychological laboratories, moving coloured lights were thus projected in order to create different chromatic environments able to influence the spectator in various ways (“Musica cromatica”, 1912).

The chromatrope is an animated slide, consisting of two glasses painted with bands of brilliant colors forming abstract ornamental patterns; the glasses are rotated in opposite directions to each other thanks to a crank frame which, once inserted into the magic lantern, allows moving color compositions to be projected onto a screen. Thanks to the public success of the shows presented at the optical theater of the Royal Polytechnic Institution in London by the painter and lanternist Henry Childe Langdon, from the 1840s the chromatrope became a very popular form of attraction in French theaters, which at the same time both an entertainment function and an educational function aimed at educating viewers about color theories. If the cultural origins of the instrument are linked to a sort of hybridization between the pre-modern tradition of pyrotechnic displays and more recent developments of industrial ornament, its longevity during the 19th century is explained rather by the evolution of its status and the scholarly discourses that accompanied it through the transition from optical physiology to the psychophysiology of color. Thanks to the captivating and repetitive movement of its multicolored rosettes, the chromatrope, with its potential for suggestive projection, seems likely to produce psychological conditioning on the spectators. By virtue of this power of suggestion, the instrument is then described both as a spectacular mechanism and as a hypnotic device with therapeutic aims.

Water- and food-related health issues have received a lot of attention recently because food-poisoning bacteria, in particular, are becoming serious threats to human health. Currently, techniques used to detect these bacteria are time-consuming and laborious. To overcome these challenges, the colorimetric strategy is attractive because it provides simple, rapid and accurate sensing for the detection of Salmonella spp. bacteria. The aim of this study is to review the progress regarding the colorimetric method of nucleic acid for Salmonella detection. A literature search was conducted using three databases (PubMed, Scopus and ScienceDirect). Of the 88 studies identified in our search, 15 were included for further analysis. Salmonella bacteria from different species, such as S. Typhimurium, S. Enteritidis, S. Typhi and S. Paratyphi A, were identified using the colorimetric method. The limit of detection (LoD) was evaluated in two types of concentrations, which were colony-forming unit ...

All-optical clock recovery is demonstrated from pseudo-data patterns at 30 Gb/s. The circuit is based on the optical gain modulation of a semiconductor optical amplifier fiber laser. The recovered clock is a 2.7-ps pulse train, with very low modulation pattern even in the presence of more than 200 consecutive 0's in the data signal.

A D-shaped polarization-maintaining fiber (PMF) as fiber optic sensor for the simultaneous monitoring of strain and the surrounding temperature is presented. A mechanical end and edge polishing system with aluminum oxide polishing film is utilized to perform sequential polishing on one side (lengthwise) of the PMF in order to fabricate a D-shaped cross-section. Experimental results show that the proposed sensor has high sensitivity of 46 pm/µε and 130 pm/ • C for strain and temperature, respectively, which is significantly higher than other recently reported work (mainly from 2013) related to fiber optic sensors. The easy fabrication method, high sensitivity, and good linearity make this sensing device applicable in various applications such as health monitoring and spatial analysis of engineering structures.

In this paper, we propose a simple approach for achieving multiwavelength tunable Brillouin-Erbium fiber lasers utilizing fiber loop mirror technique. The impact of Brillouin gain contributed by the change of single-mode fiber length on the number of channels is explained. A low threshold operation of 3.5, 4 and 8 mW is achieved at 25, 8.8 and 1.9 km respectively. Simultaneous oscillation of 20, 21 and 35 channels with equally channel spacing of 0.088 nm is obtained at the optimum Brillouin pump power and Brillouin pump wavelength for 1.9, 8.8 and 25 km respectively.

The paper endeavours the history of light and optics from the early Greek period and discusses the contributions made by philosophers and later by scientists in understanding the properties of light. Many of the thoughts expressed by Philosophers and Scientists about the nature of light have been taken from the Internet.

Discrete-mode quantum-cascade lasers have been developed in the InGaAs-AlAsSb-InP materials system. For an uncoated 10-m-wide ridge waveguide and 3000-m-long cavity, the laser had a threshold current density th of 4.2 kA cm 2 (th = 1 5 A) at 300 K with a slope efficiency of 80 mW/A. A stable singlemode emission near 3.3 m with a sidemode suppression ratio of nearly 25 dB was observed and a tuning coefficient of 0.22 nm/K was obtained in the temperature range of 253 K 303 K.

The viscosity of an optical fibre over 1000 to 1150 °C is studied by inscribing an optical fibre Bragg grating that can withstand temperatures up to 1200 °C and monitoring fibre elongation under load through the Bragg wavelength shift. This optical interrogation offers high accuracy and reliability compared to direct measurements of elongation, particularly at lower temperatures, thus avoiding significant experimental error. An excellent Arrhenius fit is obtained from which an activation energy for viscous flow of E a = 450 kJ/mol is extracted; addition of an additional temperature dependent preexponential does not change this value. This value is less than that idealised by some literature but consistent with other literature. The log plot of viscosity is overall found to be consistent with that reported in the literature for silica measurements on rod and beams, but substantially higher to past work reported for optical fibres. The discrepancy from an idealised activation energy E a ~ 700 kJ/mol may be explained by noting the higher fictive temperature of the fibre. On the other hand, past optical fibre results obtained by beam bending with much lower values leave questions regarding the method of viscosity measurement and the time taken for structural equilibration. We note that because regenerated gratings already involve post-annealing to stabilise their operation at higher temperature, the structures are much more relaxed compared to normal fibres. This work highlights the need to stabilize components for operation in harsh environments before their application, despite some mechanical compromise. Given the increasing expectation of all-optical waveguide technologies operating

The reliability and reproducibility of regenerated gratings for mass production is assessed through simultaneous bulk regeneration of 10 gratings. The gratings are characterized and variations are compared after each stage of fabrication, including seed (room-temperature UV fabrication), regeneration (annealing at 850°C), and postannealing (annealing at 1100°C). In terms of Bragg wavelength (λ B), the seed grating variation lies within Δλ B 0.16 nm, the regenerated grating within Δλ B 0.41 nm, and the postannealed grating within Δλ B 1.42 nm. All the results are within reasonable error, indicating that mass production is feasible. The observable spread in parameters from seed to regenerated grating is clearly systematic. The postannealed spread arises from the small tension on the fiber during postannealing and can be explained by the softening of the glass when the strain temperature of silica is reached.

Transmission characteristics of nonlinear one dimensional photonic crystal with a defect have been studied. GaAs/Si multilayer structure with a single defect has been simulated using transfer matrix method. In this study refractive indices of both layers have been taken to be dependent on intensity and wavelength simultaneously. It is found that central wavelength of defect mode change with intensity of wave. Average change in central wavelength of defect mode is 0.02 nm/(1 GW/cm 2). This property can be exploited in the design of a single channel tunable wavelength division demultiplexer for optical communication.

An experimental study of a tunable 60 GHz multiwavelength Brillouin erbium fiber laser is presented in this paper. Two unidirectional ring laser cavities and two pre-amplification laser cavities are used. In the first three cavities, a Brillouin gain medium is presented with a dispersion compensation fiber (DCF) spool, and a single-mode fiber (SMF) spool is used as a Brillouin gain medium in the fourth cavity. Three erbium amplifiers are utilized to supply enough gain to the generated Brillouin Stokes signal and to suppress cavity losses. For these three amplifiers, up to 450 mW (150 mW for each) of a 1480 nm pump power is used. In our proposed configuration, four sextuple Brillouin Stokes signals with a high power of 10 dBm and more than 55 dB as an optical signal-to-noise ratio are achieved. The obtained Brillouin Stokes signals can be tuned over 30 nm (1560–1590 nm) and can be easily used in dense wavelength division multiplexing in optics communication systems.

All-optical devices allow improvements in the speed of optical communication and computation systems by avoiding the conversion between the optical and electronic domains. The focus of this thesis is the experimental investigation of a new type of all-optical switch that is based on the control of optical patterns formed by nonlinear interactions between light and matter. My approach to all-optical switching is simple, extremely sensitive and exhibits many of the properties necessary for use as an optical logic element. Additionally, this work has implications for a wide range of pattern forming systems, both in the field of optics and beyond, that may be applicable as novel devices for sensitive measurement and detection.

DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Semiconductor laser diodes are important components for various applications such as 5G wireless, datacenter, passive optical network, and aerospace applications. High reliability has emerged to be the universal requirement for all optical applications. To achieve high reliability, fundamental understanding of the laser degradation behavior is crucial. In this paper, we study three cases of gradual degradataion modes of laser diodes including (1) Pattern-A that is associated with threshold current change only, (2) Pattern-B that involve both threshold current and power changes, and (3) Pattern-C that is associated with merely power change. We have instituted reliability equations for the degradation processes. The new reliability models could provide estimation on the laser end-of-life based on the degradation rate and device performance specification.

This paper describes the design of Mach Zehnder Interferometer and reviews its applications in emerging optical communication networks. Mach Zehnder Interferometer is basically used to measure relative phase shift between two collimated beams from a coherent light source. Using this basic principle a number of devices can be designed, few of these such as optical sensors, all-optical switches, optical add-drop multiplexer and modulator are discussed in this paper.

The practical implementation of free-space quantum information tasks requires entanglement to be sustained over long distances and in the presence of turbulent and noisy environments. The transverse position-momentum entanglement of photon pairs produced by parametric down-conversion has found several uses in quantum information science, however, it is not suitable for applications involving long-distance propagation as the entanglement decays very rapidly when photons propagate away from their source. Entanglement is lost after a few centimetres of propagation, and the effect becomes even more pronounced in turbulent environments. In contrast, in this article, we show that entanglement in the angle-orbital angular momentum (OAM) bases exhibits a remarkably different behaviour. As with the position-momentum case, initially, the angle-OAM entanglement decays with propagation, but as the photons continue to travel further from the source, the photons regain their strongly correlated b...

The Raman gain based polarization pulling process in a copropagating scheme is investigated. We map the degree of polarization, the angle between the signal and pump output Stokes vectors, the mean signal gain and its standard deviation considering the entire Raman gain bandwidth. We show that, in the undepleted regime (signal input power ∼ 1 μW), the degree of polarization is proportional to the pump power and changes with the signal wavelength, following the Raman gain shape. In the depleted regime (signal input power 1mW), the highest values for the degree of polarization are no more observed for the highest pump powers. Indeed, we show that exists an optimum pump power leading to a maximum degree of polarization.

The persistent photoinduced magnetization (PPM) in the low bandwidth material Pr 1−x Ca x MnO 3 at the low hole doping level of x = 0.1 is reported. Upon zero-field cooling under photoexcitation, significant improvement of the ferromagnetic (FM) ordering was observed in the low temperature spin-glass phase. However, upon field cooling, the FM ordering was found to be suppressed due to weakening of the double-exchange interaction. High kinetic energy x-ray photoelectron spectroscopy measurements indicated a slight increase in the Mn 3+ peak under photoexcitation which clarifies the weakening of the FM interaction. The fast relaxation of the PPM is discussed in view of localization of spin polarons in sites of magnetic disorders and the results are compared with previous reports of PPM in intermediate bandwidth La 0.9 Ca 0.1 MnO 3 samples.

All-optical clock recovery is demonstrated from pseudo-data patterns at 30 Gb/s. The circuit is based on the optical gain modulation of a semiconductor optical amplifier fiber laser. The recovered clock is a 2.7-ps pulse train, with very low modulation pattern even in the presence of more than 200 consecutive 0's in the data signal.

In this paper, we have experimentally demonstrated thermal regeneration of gratings at 1310 and 1560 nm in the hydrogenated boron/germanium codoped photosensitivity fibers. Increase in effective index of the fiber and reduced grating period are observed in the regenerated fiber Bragg grating (RFBG). The experimental results show that the temperature sensitivity of regenerated gratings at 1310 and 1560 nm is 8.7 and 12.8 pm/°C, respectively, and the RFBG with larger period withstand a higher thermal stability.

Conventional evanescent optical devices have made use of etched windows to allow access of an optical field to a material of interest. Such devices are a route to accurate refractive index sensors and to realising modulators, however, the geometry of etching the cladding to give the fluid access to a pre-defined core waveguide mode is limiting. In this work, we present an alternative approach in which a groove is cut using a polishing saw blade to give a vertical, high optical quality trench. Optical waveguides are then UV written to allow evanescent lateral access of the mode to a fluid placed in the trench. This seemingly subtle change in geometry provides greatly increased flexibility to tailor the interaction between the optical mode and the surrounding material, by, for example, changing the mode size and the allowing couplers or tapers to be used.

We demonstrate liquid crystal-based integrated optical devices with >140GHz electrical tuning for potential applications in dynamic optical networks. Bragg wavelength tuning covering five 25GHz WDM channel spacings has been achieved with 170V (peak-to-peak) sinusoidal voltages applied across electro-patterned ITO-covered glass electrodes placed 60µm apart. This tunability range was limited only by the initial grating strength and supply voltage level. We also observed two distinct threshold behaviors that manifest during increase of supply voltage, resulting in a hysteresis in the tuning curve for both TE and TM input light. OCIS codes: (130.0130) Integrated optics; (130.3120) Integrated optics devices; (230.0230) Optical devices; (230.2090) Electro-optical devices Introduction: Increasingly fast and high density wavelength division multiplexing (WDM) networks place stringent requirements on channel spacing and integrity. With 25GHz channel spacings becoming more commonplace, the ability to dynamically add and drop channel information will increase network scalability and reach while keeping operational

An automated experimental setup for investigating the mechanisms of refractive index change in optical fibers at high temperatures is described. A resistive furnace that allows a section of an optical fiber to be heated from room temperature to 1200 ° C at a given rate was developed. The results from experiments on annealing gratings formed in a germanosilicate fiber with 14 mol % GeO 2 in the fiber core are presented. The temperature stability of photoinduced fiber refractive index gratings at different demarcation energies was calculated on the basis of the data obtained.

The authors demonstrate a novel all-optical T-flip-flop (TFF) layout utilizing a single optical latching element that comprises an integrated semiconductor optical amplifier and Mach-Zehnder inteferometer and a feedback loop. Experimental proof-of-concept verification is presented at 8 Mb/s using off-the-shelf bulk components and a fiber-based feedback implementation. The proposed TFF architecture requires the minimum number of active components and just a single toggling signal as input. Its simple circuit design is amenable with photonic integration and holds the credentials for operation at multi-Gb/s speeds.

Increasing demand for power reduction in computer systems has led to new trends in computations and computer design including reversible computing. Its main aim is to eliminate power dissipation in logical elements but can have some other advantages such as data security and error prevention. Because of interesting properties of reversible computing, implementing computing devices with reversible manner is the only way to make the reversible computing a reality. In recent years, reversible logic has turned out to be a promising computing paradigm having application in CMOS, nanotechnology, quantum computing and optical computing. In this paper, we propose and realize a novel implementation of Toffoli gate in all-optical domain. We have explained its principle of operations and described an actual experimental implementation. The all-optical reversible gate presented in this paper will be useful in different applications such as arithmetic and logical operations in the domain of reversible logic-based computing.

The authors demonstrate a novel all-optical T-flip-flop (TFF) layout utilizing a single optical latching element that comprises an integrated semiconductor optical amplifier and Mach-Zehnder inteferometer and a feedback loop. Experimental proof-of-concept verification is presented at 8 Mb/s using off-the-shelf bulk components and a fiber-based feedback implementation. The proposed TFF architecture requires the minimum number of active components and just a single toggling signal as input. Its simple circuit design is amenable with photonic integration and holds the credentials for operation at multi-Gb/s speeds.