Minimum Repetition Research Articles

Vanadium Aluminium Carbide Saturable Absorber in Passively Q-switched Erbium-doped Fibre Laser

Following the success of graphene saturable absorber (SA) in the development of passively Q-switched fibre lasers within the past decade, research on two-dimensional (2-D) nanomaterials SAs have shown a significant rise in demands. Nonetheless, there have been several unavoidable setbacks due to the nature of certain nanomaterials, in terms of optical, electronic and physical properties up until the reveal of transition metal carbide (MXene) nanomaterials. These metal-ceramic materials exhibit excellent optical and electrical properties as well as outstanding physical characteristics. However, their synthesis processes involve hazardous and highly acidic chemicals, which drove the researchers to adopt their precursors— ternary nanolaminate carbides (MAX phases) nanomaterials with a simpler and more exquisite fabrication process. This paper presents a passively Q-switched erbium-doped fibre laser (EDFL) with the utilisation of a MAX phases nanomaterial, vanadium aluminium carbide (V4AlC3) as SA. The V4AlC3 SA was fabricated through the solution casting technique with polyvinyl alcohol as the host polymer. The V4AlC3 SA was then integrated into a passively Q-switched EDFL configuration. The performance of V4AlC3 SA as a Q-switcher was determined with the assistance of an optical spectrum analyser (OSA), mixed domain oscilloscope (MDO), and optical power meter (OPM). The maximum pulse repetition rate and minimum pulse width were 54.37 kHz and 6.43 ms, respectively. The minimum repetition interval was 18.33 ms and the duty cycle was 0.326. The highest attained output power was 2.5 mW. Through calculation, the maximum pulse energy and peak power were identified as 45.246 nJ and 6.602 mW. The extensively gigantic pulses in nanosecond duration at 1560.16 nm was accomplished by the V4AlC3 SA, thus proving its stability which also signifies good applications especially those acquiring stable high power and energy.

Molybdenum gallium carbide saturable absorber as Q-switcher in an erbium-doped fibre laser

In this research work, molybdenum gallium carbide (Mo2Ga2C)—fabricated as a thin film via solution casting technique—was first introduced as a saturable absorber (SA) to regulate the intracavity losses in a Q-switched fibre laser. The fabricated Mo2Ga2C SA had undergone both optical and physical interpretations prior to its employment as a Q-switcher in an erbium-doped fibre laser (EDFL) ring cavity configuration, sandwiched in between the end-facets of the optical fibre ferrules. The Q-switched wavelength was observed at 1532.07 nm and the Q-switching parameters were determined, accordingly. The temporal parameters of Q-switched EDFL, which include the maximum pulse repetition rate, minimum repetition period and minimum pulse duration were indicated as 107.60 kHz, 9.29 μs, and 5.52 μs, correspondingly. The maximum output power, peak power and pulse energy of the Mo2Ga2C-PVA SA as the Q-switcher were 7.3 mW, 11.47 mW and 67.38 nJ, in accordance with a slope efficiency of 7.39 % and signal-to-noise (SNR) ratio of 57.6 dB.

10 Hz Stable Mode-locked Er-Fiber Laser

Abstract: In this paper, a stable output at the reduction repetition rate from 80 MHz mode-locked Er-doped fiber laser (EDFL) was demonstrated by adjusting the operating point for external LiNbO3 Mach-Zehnder‎ electro-optic intensity modulator to suppress harmonic mode-locked pulses. More than 70% of the laser beam was launched into the external pigtail Mach-Zehnder intensity modulator using single mode fiber with collimating lens and fiber (ferrule connector) FC adapter. The optimum values of Mach-Zehnder modulator bias voltages V0 and Vπ (half wave voltage) which resulted in maximum and minimum laser output power to leave the modulator were found at 6.5 and 0.29 V, respectively. The best modulation was achieved for the RF modulating signal with an opening time of about 8 ns. For driving voltage equal to Vπ, a clean mode-locked pulse train was generated with a pulse shape and energy similar to the input pulse, albeit with a low repetition rate. The minimum repetition rate reached as low as 10 Hz, resulting in pulse energy and peak power of 0.32 nJ and 1.5 kW, respectively. Second-harmonic generation of the low repetition rate pulse train was also produced by using a PPLN crystal. This opens up the potential for using this laser in single photon detection experiments and as a seed laser for many applications. Keywords: Er-fiber laser, Passively mode-locked fiber laser, Nonlinear polarization rotation, Mach-Zehnder modulator, Fast electro-optic modulator. PACS: Fiber lasers, 42.55.Wd, Mode locking, 42.60.Fc.

Source performance metrics for EUV mask inspection

Rules are derived to obtain specifications on radiance, power, lifetime, and cleanliness of the source for an actinic patterned mask inspection system. We focus on the physical processes and technological aspects governing the requirements of radiation sources for reticle inspection. We discuss differences and similarities to scanner with respect to magnification, system etendue, and image recording. Source radiance requirements are estimated from a perspective of targeted throughput and defect detection sensitivity. The derivations consider the influence of photon shot noise on signal detection and conservation laws of light etendue and radiant flux. We describe the scaling laws for required radiance with targeted sensitivity index, optical contrast, field size, and system throughput. In addition, we address the limits on the required brightness and minimum repetition rate set by mask damage threshold. Finally, system and source cleanliness requirements and criticality of the source availability and lifetime are discussed. The analysis can be applied to other microscopy-based metrology and inspection applications.

The use of User-centered Design Canvas for Rapid Prototyping

This paper presents the use of User-Centered Design Canvas to help students design the user experience (UX) on the designated Collaborative Projects. The Collaborative Project itself has been conducted by students with multi-discipline backgrounds. The User-Centered design itself was widely used as an approach to software development in order to achieve better alignment between the user experience and the business goal. Adopting Business Model Canvas, the User-Centered Design Canvas was introduced as an acceleration tool for rapid prototyping and ensures the effectiveness and efficient manner for the sake of user satisfaction. As the results from the questionnaire, more than 78% of users express the benefits of the current adaptation of User-Centered Design Canvas. Also from the Log Metric Analysis, users2 have completed a designated task under 5 minutes with minimum repetition. This indicates that the use of proposed adaptation is easy to use and shows the effectiveness of the User-Centered Design Canvas for rapid prototyping.

Performance evaluation of natural esters and dielectric correlation assessment using artificial neural network (ANN)

The performance of correlation between the dielectric parameters of Baobab Oil (BAO) and Mongongo Oil (MGO) is evaluated using Artificial Neural Network (ANN). The BAO and MGO naturally own high Unsaturated Fatty Acids (UFAs) and are highly biodegradable. The temperature studies and dielectric studies are carried out and found that the Natural Esters (NEs) show a reliable performance over mineral oil-based Transformer Oil (TO). Further the endurance test, Partial Discharge Inception Voltage (PDIV) repetition rate and drop after 30 days, dielectric measurements are done as per the standards of IEC (International Electrotechnical Commission) and ASTM (American Society for Testing and Materials). The NEs show stable performance under PDIV and show minimum repetition rate when compared to the TO. The C[Formula: see text]H[Formula: see text] or Kerosene (KER) and NEs mixture prove that the NE-based transformer fluids show lesser tendency to hydro peroxidation. The C[Formula: see text]H[Formula: see text] acts as a thinning agent and reduces the ageing rate of the NEs, and this leads to slower rate of water saturation. This in turn increases the thermal conductivity of the oil and nearly a 30-days thermal ageing of the oil samples at 90[Formula: see text]C shows better strength of liquid insulation. The performance of association between the dielectric properties like breakdown voltage and water content, dissipation factor and thermal conductivity prove that the NEs show consistent performance and is a better substitute for the mineral oil-based TO.

Highly efficient head-only magnetic field insert gradient coil for achieving simultaneous high gradient amplitude and slew rate at 3.0T (MAGNUS) for brain microstructure imaging.

To develop a highly efficient magnetic field gradient coil for head imaging that achieves 200 mT/m and 500 T/m/s on each axis using a standard 1 MVA gradient driver in clinical whole-body 3.0T MR magnet. A 42-cm inner diameter head-gradient used the available 89- to 91-cm warm bore space in a whole-body 3.0T magnet by increasing the radial separation between the primary and the shield coil windings to 18.6 cm. This required the removal of the standard whole-body gradient and radiofrequency coils. To achieve a coil efficiency ~4× that of whole-body gradients, a double-layer primary coil design with asymmetric x-y axes, and symmetric z-axis was used. The use of all-hollow conductor with direct fluid cooling of the gradient coil enabled ≥50 kW of total heat dissipation. This design achieved a coil efficiency of 0.32 mT/m/A, allowing 200 mT/m and 500 T/m/s for a 620 A/1500 V driver. The gradient coil yielded substantially reduced echo spacing, and minimum repetition time and echo time. In high b = 10,000 s/mm2 diffusion, echo time(TE) < 50 ms was achieved (>50% reduction compared with whole-body gradients). The gradient coil passed the American College of Radiology tests for gradient linearity and distortion, and met acoustic requirements for nonsignificant risk operation. Ultra-high gradient coil performance was achieved for head imaging without substantial increases in gradient driver power in a whole-body 3.0T magnet after removing the standard gradient coil. As such, any clinical whole-body 3.0T MR system could be upgraded with 3-4× improvement in gradient performance for brain imaging.

RETRACTED ARTICLE: Automatic detection of lung cancer from biomedical data set using discrete AdaBoost optimized ensemble learning generalized neural networks

Today, most of the people are affected by lung cancer, mainly because of the genetic changes of the tissues in the lungs. Other factors such as smoking, alcohol, and exposure to dangerous gases can also be considered the contributory causes of lung cancer. Due to the serious consequences of lung cancer, the medical associations have been striving to diagnose cancer in its early stage of growth by applying the computer-aided diagnosis process. Although the CAD system at healthcare centers is able to diagnose lung cancer during its early stage of growth, the accuracy of cancer detection is difficult to achieve, mainly because of the overfitting of lung cancer features and the dimensionality of the feature set. Thus, this paper introduces the effective and optimized neural computing and soft computing techniques to minimize the difficulties and issues in the feature set. Initially, lung biomedical data were collected from the ELVIRA Biomedical Data Set Repository. The noise present in the data was eliminated by applying the bin smoothing normalization process. The minimum repetition and Wolf heuristic features were subsequently selected to minimize the dimensionality and complexity of the features. The selected lung features were analyzed using discrete AdaBoost optimized ensemble learning generalized neural networks, which successfully analyzed the biomedical lung data and classified the normal and abnormal features with great effectiveness. The efficiency of the system was then evaluated using MATLAB experimental setup in terms of error rate, precision, recall, G-mean, F-measure, and prediction rate.

Volumetric MRI thermometry using a three-dimensional stack-of-stars echo-planar imaging pulse sequence.

To measure temperature over a large brain volume with fine spatiotemporal resolution. A three-dimensional stack-of-stars echo-planar imaging sequence combining echo-planar imaging and radial sampling with golden angle spacing was implemented at 3T for proton resonance frequency-shift temperature imaging. The sequence acquires a 188x188x43 image matrix with 1.5x1.5x2.75 mm3 spatial resolution. Temperature maps were reconstructed using sensitivity encoding (SENSE) image reconstruction followed by the image domain hybrid method, and using the k-space hybrid method. In vivo temperature maps were acquired without heating to measure temperature precision in the brain, and in a phantom during high-intensity focused ultrasound sonication. In vivo temperature standard deviation was less than 1°C at dynamic scan times down to 0.75 s. For a given frame rate, scanning at a minimum repetition time (TR) with minimum acceleration yielded the lowest standard deviation. With frame rates around 3 s, the scan was tolerant to a small number of receive coils, and temperature standard deviation was 48% higher than a standard two-dimensional Fourier transform temperature mapping scan, but provided whole-brain coverage. Phantom temperature maps with no visible aliasing were produced for dynamic scan times as short as 0.38 s. k-Space hybrid reconstructions were more tolerant to acceleration. Three-dimensional stack-of-stars echo-planar imaging temperature mapping provides volumetric brain coverage and fine spatiotemporal resolution. Magn Reson Med 79:2003-2013, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

An exploration of task based fMRI in neonates using echo-shifting to allow acquisition at longer TE without loss of temporal efficiency

Optimal contrast to noise ratio of the BOLD signal in neonatal and foetal fMRI has been hard to achieve because of the much longer T2⁎ values in developing brain tissue in comparison to those in the mature adult brain. The conventional approach of optimizing fMRI sequences would suggest matching the echo time (TE) and the T2⁎ of the neonatal and foetal brain. However, the use of a long echo time would typically increase the minimum repetition time (TR) resulting in inefficient sampling.Here we apply the concept of echo shifting to task based neonatal fMRI in order to achieve an improved contrast to noise ratio and efficient data sampling at the same time. Echo shifted EPI (es-EPI) is a modification of a standard 2D-EPI sequence which enables echo times longer than the time between consecutive excitations (TE>TS=TRNS, where NS is the number of acquired slices and TS the inter-slice repetition time). The proposed method was tested on neonatal subjects using a passive sensori-motor task paradigm. Dual echo EPI datasets with an identical readout structure to es-EPI were also acquired and used as control data to assess BOLD activation.From the results of the latter analysis, an average increase of 78±41% in contrast to noise ratio was observable when comparing late to short echoes. Furthermore, es-EPI allowed the acquisition of data with an identical contrast to the late echo, but more efficiently since a higher number of slices could be acquired in the same amount of time.

A novel approach for mining cyclically repeated patterns with multiple minimum supports

Periodic patterns and cyclic patterns have been used to discover recurring patterns in sequence databases. Toroslu (2003) proposed cyclically repeated pattern (CRP) mining, in which a new parameter called repetition support is considered in the mining process. In a data sequence, the occurrence of a subsequence must satisfy a single user-specified minimum repetition support. However, in real-life applications, items may occur at various frequencies in a database. The rare item problem may occur when all items are set to a single minimum repetition support. To solve this problem, we included the concept of multiple minimum supports to enable users to specify the multiple minimum item repetition support (MIR) according to the natures of items. In this paper, we first redefined CRPs based on the MIR and original form of the sequence minimum support. A new algorithm, rep-PrefixSpan, was developed for discovering a complete set of CRPs in sequence databases. The experimental results indicate that the proposed approach exhibits performance superior to that of conventional CRP mining. The proposed method can be applied in many application domains including customer purchase behavior, web logging, and stock analyses.

Harvesting techniques for non-industrial SRF biomass plantations on farmland

&lt;p&gt;The goal of this study was to compare the technical and economic performance of terrain chipping and roadside chipping, applied to short rotation biomass plantations. The null hypothesis was that no significant difference are in the performance of the two work systems, when applied to short rotation coppices. Those systems especially designed for non-industrial SRF plantations, were used for conventional logging operations. The difference on the above mentioned systems consisted especially in the chipping location: chipping was performed directly to the field (containers reach the chipper in the field) or at the field’s edge (roadside chipping). Both systems were tested on two of the most common SRF poplar clones in Italy, namely: AF2 and Monviso. Plots were allocated randomly to the two treatment levels ( roadside or field chipping) than blocked for two main clone types ( AF2 and Monviso ) so that each of the 4 treatments level and clone types has a minimum repetition plot of 6 times (total of 24 replications). The Plot were identified with paint markings at the stump so each plot area could be identified at the ground. Net weight of each charge was obtained by a certified weighbridge, so each plot has its own productivity in terms of weight and time consumption. Results were encouraging: harvesting cost varied from 16.3 to 23.2 􀀔 tonne-1, and was lower for terrain chipping and for the most productive clone (Monviso). Despite its higher cost, roadside chipping was preferred for its better terrain capability and for the superior storage quality of uncomminuted biomass. Both systems were suboptimal in their current configurations. They could offer a better performance, subject to minor improvements.&lt;/p&gt;

Harvesting techniques for non-industrial SRF biomass plantations on farmland

The goal of this study was to compare the technical and economic performance of terrain chipping and roadside chipping, applied to short rotation biomass plantations. The null hypothesis was that no significant difference are in the performance of the two work systems, when applied to short rotation coppices. Those systems especially designed for non-industrial SRF plantations, were used for conventional logging operations. The difference on the above mentioned systems consisted especially in the chipping location: chipping was performed directly to the field (containers reach the chipper in the field) or at the field’s edge (roadside chipping). Both systems were tested on two of the most common SRF poplar clones in Italy, namely: AF2 and Monviso. Plots were allocated randomly to the two treatment levels ( roadside or field chipping) than blocked for two main clone types ( AF2 and Monviso ) so that each of the 4 treatments level and clone types has a minimum repetition plot of 6 times (total of 24 replications). The Plot were identified with paint markings at the stump so each plot area could be identified at the ground. Net weight of each charge was obtained by a certified weighbridge, so each plot has its own productivity in terms of weight and time consumption. Results were encouraging: harvesting cost varied from 16.3 to 23.2 􀀔 tonne-1, and was lower for terrain chipping and for the most productive clone (Monviso). Despite its higher cost, roadside chipping was preferred for its better terrain capability and for the superior storage quality of uncomminuted biomass. Both systems were suboptimal in their current configurations. They could offer a better performance, subject to minor improvements.

WE‐C‐116‐02: High Resolution C‐13 MRI with Hyperpolarized [C‐13,N‐15] Urea

Purpose: To demonstrate an increase spin‐spin relaxation time (T2) of hyperpolarized carbon‐13 urea by nitrogen‐15 labeling its amide groups, and to show how this enables background‐free perfusion MRI at 1 mm in‐plane resolution with SNR &gt; 300. Methods: In vivo hyperpolarized dual‐labeled [C13,N‐15]urea and singly‐labeled [C13]urea images were acquired dynamically in a rat using a using a steady state free precession (SSFP) and fast low angle shot (FLASH) acquisitions on a clinical 3T MRI scanner. Dynamic images were fit pixel‐wise to an exponential function to create effective decay constant maps. T2 measurements using Carr Purcell Meiboom Gill (CPMG) sequences on hyperpolarized samples were also performed. Results: Measured T2 values were 90±15 ms for [C13]urea and 24±4 s for [C13,N‐15]urea; the in vivo estimate of the T2 of [C13,N‐15]urea was 1.4 s. Concordant with analytic signal models, hyperpolarized imaging with [C‐13,N‐15] urea showed SNR improvements of 5.1±2.3 and 3.5±1.1 compared to [C13]urea imaged with FLASH and SSFP respectively. Exponential decay maps showed delineation of the renal cortex, medulla, and pelvis, with renal columns (medullary cortical extensions) visible. Conclusion: The large SNR gain achievable using [C13,N‐15]urea could be utilized for a corresponding resolution enhancement, which greatly improves the image quality when using this completely endogenous probe. This probes low toxicity could enable contrast angiography on patients with diminished renal function, even with large intravenous doses. Since clinical MRI scanners have longer minimum repetition time requirements due to safety and hardware constraints, the long T2 of [C13,N‐15]urea measured in this study facilitates SSFP or spin echo train imaging of hyperpolarized for clinical applications. The delineation of the renal structures suggests a possible application of renal function assessment.

A 1.5T MRI‐conditional 12‐lead electrocardiogram for MRI and intra‐MR intervention

High-fidelity 12-lead electrocardiogram (ECG) is important for physiological monitoring of patients during MR-guided intervention and cardiac MRI. Issues in obtaining noncorrupted ECGs inside MRI include a superimposed magneto-hydro-dynamic voltage, gradient switching-induced voltages, and radiofrequency heating. These problems increase with magnetic field. The aim of this study is to develop and clinically validate a 1.5T MRI-conditional 12-lead ECG system. The system was constructed with transmission lines to reduce radiofrequency induction and switching circuits to remove induced voltages. Adaptive filters, trained by 12-lead measurements outside MRI and in two orientations inside MRI, were used to remove the magneto-hydro-dynamic voltage. The system was tested on 10 (one exercising) volunteers and four arrhythmia patients. Switching circuits removed most imaging-induced voltages (residual noise <3% of the R-wave). Magneto-hydro-dynamic voltage removal provided intra-MRI ECGs that varied by <3.8% from those outside the MRI, preserving the true S-wave to T-wave segment. In premature ventricular contraction (PVC) patients, clean ECGs separated premature ventricular contraction and sinus rhythm beats. Measured heating was <1.5°C. The system reliably acquired multiphase (steady-state free precession) wall-motion-cine and phase-contrast-cine scans, including subjects in whom 4-lead gating failed. The system required a minimum repetition time of 4 ms to allow robust ECG processing. High-fidelity intra-MRI 12-lead ECG is possible.

Fast algorithms for finding a minimum repetition representation of strings and trees

A string with many repetitions can be represented compactly by replacing h-fold contiguous repetitions of a string r with (r)h. We present a compact representation, which we call a repetition representation (of a string) or RRS, by which a set of disjoint or nested tandem arrays can be compacted. In this paper, we study the problem of finding a minimum RRS or MRRS, where the size of an RRS is defined by the sum of the length of component letters and the description length of the component repetitions (⋅)h which is defined by wR(h) using a repetition weight function wR. We develop two dynamic programming-based algorithms to solve this problem: CMR, which works for any type of wR, and CMR-C, which is faster but can be applied to a constant wR only. CMR-C is an O(n2logn)-time O(nlogn)-space algorithm, which is more efficient in both time and space than CMR by a ((logn)/n)-factor, where n is the length of the given string. The problem of finding an MRRS for a string can be extended to that of finding a minimum repetition representation (of a tree) or MRRT for a given labeled ordered tree. For this problem, we present two algorithms, CMRT and CMRT-C, by using CMR and CMR-C, respectively, as a subroutine. As well as the theoretical analysis, we confirmed the efficiency of the proposed algorithms by experiments, which consist of the following three parts: First we demonstrated that CMR-C and CMRT-C are fast enough for large-scale data by using synthetic strings and trees, respectively. The size of an MRRS for a given string can be a measure of how compactly the string can be represented, meaning how well the string is structurally organized. This is also true of trees. To check such ability of MRRS-size, second we measured the size of an MRRS for chromosomes of nine different species. We found that all the chromosomes of the same species have a similar compression rate when realized by an MRRS. Run length encoding (RLE) was also shown to have species-specific compression rate, but species were separated more clearly by MRRS than by RLE. Third we examined the size of an MRRT for web pages of world-leading companies by using the tag trees, showing a consistency between the compression rate by an MRRT and visual web page structures.

Comparison of the Outcome of Treatment of Chronic Osteomyelitis by Surgical Debridement with and without Local Antibiotic Delivery System: Experience from a Nigerian Teaching Hospital

Background: Chronic osteomyelitis is still common in the developing world and presents a continuing therapeutic challenge. Antibiotics cannot penetrate the dense fibrotic scar tissue that surrounds infected and avascular bone which perpetuates the infection. Surgical debridement/sequestrectomy is the cornerstone to treatment and aims to create a viable, vascularized base which promotes healing. Surgical debridement necessarily creates a dead space which must be dealt with to prevent re-infection. Local antibiotic delivery systems serve the dual purpose of obliterating dead space and creating a sterile local environment with high bactericidal concentrations. Aim: To determine the outcomes in patients with chronic osteomyelitis who received debridement/sequestrectomy alone, and those who received the procedure combined with a local antibiotic delivery system in the University of Calabar Teaching Hospital. Patients and Methods: A prospective descriptive analysis of patients managed surgically for chronic osteomyelitis from July 2007 to December, 2012. Patients’ biodata, aetiology, organisms, treatment options and outcomes were analysed. Results: Forty-four patients presented with the condition and accepted surgery. Male:Female ratio was 2.1:1, and mean age was 27.27 ± 17.48 years. The tibia was the most commonly affected bone (45.5%), Staphylococcus aureus was the commonest organism (56.8% of sinus cultures; 73% of marrow/sequestral cultures) and previous acute haematogenous osteomyelitis was the commonest mechanism. The use of a local antibiotic delivery system improved cure rates from 57.7% to 77.8%). Conclusion: Multiple surgical interventions increase the socioeconomic costs of treating this condition and have a direct impact on the economies of individuals especially in the developing world. Surgical interventions should aim at achieving maximum impact with minimum repetition of the processes. Adequate surgical debridement combined with a local antibiotic delivery system offer improved chances of obtaining cure in this therapeutically challenging disease.

The limiting possibilities of interference photolithography implemented in the visible region on thin films of glassy chalcogenide semiconductor

This paper presents the results of investigating the parameters (minimum repetition period of the elements and porosity) of structures obtained under the action of argon laser radiation on thin films of glassy chalcogenide semiconductor deposited on layers of x-ray-amorphous chromium. It is shown that thin films of a three-component glassy semiconductor exposed by radiation with wavelength 0.488 µm can be used in the method of interference photolithography to obtain structures with a minimum period of 260 nm and a minimum size of the structural element of 65 nm. It is established that the minimum size of a structural element can be reduced to 50 nm when the repetition period of the elements is increased to 600 nm by using the “two-mask” technology of interference photolithography.

THE DEFINITION OF THE EUROPEAN ALMOND CORE COLLECTION

THE DEFINITION OF THE EUROPEAN ALMOND CORE COLLECTION

SOA-based loop mirror for tunable pulse-width generation

We propose and experimentally demonstrate a system for the generation of pulses of tunable pulse-width as those required in high spectral efficiency optically routed networks. Pulse narrowing of 500 ps pulses by 90% is accomplished through a SOA based non-linear loop mirror. Optical switching through the SOA loop mirror is used to shape and carve these large pulses (e.g., 500 ps) generated by non-expensive low-frequency optoelectronic components to narrow pulses (e.g., 50 ps). We also calculate the minimum loop size and optimum repetition rate of the original pulse train for the generation of the shorter pulse-width pulse train.