EDFA and Optical Fiber Repositioning in an Optical Fiber Communication Network

This study shows an easy and effective design of an optical fiber communication system, which demonstrates EDFA's ideal position in the whole system. In recent years, erbium-doped fiber amplifiers (EDFAs) have been more attentive with the development of high-speed and long-distance data transmission systems. In our research, EDFA's forward pump capacity is maintained at 100mW, and our three configurations modify and analyze the location of EDFA. First configuration is meant to place EDFA before optical fiber in the entire system. The second arrangement has been intended such that EDFA will precede optical fiber. EDFA is inserted in the third configuration between the optical fiber length. For the three setups, the BER, Q factor and output power level were observed, with the setup one having minimal BER, setup two with the greatest power, and setup three with the maximum Q factor. This paper discusses the causes behind these results and designers may construct an optical fiber communication system in the most efficient and reliable fashion by taking those results into consideration. The simulation was performed in Opti-System software. Keywords: EDFA, BER, Q factor, Analyzer, Optical fibre

Microdrilled tapers to enhance optical fiber lasers for sensing

In this work, an experimental analysis of the performance of different types of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror is presented. These artificially-controlled backscattering fiber reflectors are used in short linear cavity fiber lasers. In particular, laser emission and sensor application features are analyzed when employing optical tapered fibers, micro-drilled optical fibers and 50 μm-waist or 100 μm-waist micro-drilled tapered fibers (MDTF). Single-wavelength laser with an output power level of about 8.2 dBm and an optical signal-to-noise ratio of 45 dB were measured when employing a 50 μm-waist micro-drilled tapered optical fiber. The achieved temperature sensitivities were similar to those of FBGs; however, the strain sensitivity improved more than one order of magnitude in comparison with FBG sensors, attaining slope sensitivities as good as 18.1 pm/με when using a 50 μm-waist MDTF as distributed reflector.

GaN Based HEMT Power Amplifier Design with 44.5dBm Output Power Operating at 5-7GHz

The next-generation wireless communication systems including satellite, radar, and mobile communications need application-specific power amplifiers that can operate at very high frequencies and high power with the overall minimum power consumption from the system. To meet such stringent requirements there is a rising interest in amplifier designs based on GaN transistors. This paper presents an improved design of a high power amplifier based on GaN HEMT transistor operating at the frequency band 5GHz – 7GHz with optimized output power level. The presented design is based on a 12 Watt Discrete Power GaN on SiC HEMT from TriQuint. In this manuscript, we have considered the stability of the amplifier for the whole operating frequency band, its input and output matching impedance, gain, and maximum output power. The design of the Radio Frequency (RF) power amplifier and its overall performance are carried out using an advanced design system (ADS). The simulation results of the device stability and the output power level achieved provides a good comparison with the parameters and specifications of the device used. For better correlations in the simulation results and measurements, the accuracy of passive element designs are also considered. The simulation and experiment results show that the designed high power amplifier has achieved an output power level of 44.5 dBm at 1 dB compression point.

Zigzag Multirod Laser Beam Merging Approach for Brighter TEM00-Mode Solar Laser Emission from a Megawatt Solar Furnace

An alternative multirod solar laser end-side-pumping concept, based on the megawatt solar furnace in France, is proposed to significantly improve the TEM00-mode solar laser output power level and its beam brightness through a novel zigzag beam merging technique. A solar flux homogenizer was used to deliver nearly the same pump power to multiple core-doped Nd:YAG laser rods within a water-cooled pump cavity through a fused silica window. Compared to the previous multibeam solar laser station concepts for the same solar furnace, the present approach can allow the production of high-power TEM00-mode solar laser beams with high beam brightness. An average of 1.06 W TEM00-mode laser power was numerically extracted from each of 1657 rods, resulting in a total of 1.8 kW. More importantly, by mounting 399 rods at a 30° angle of inclination and employing the beam merging technique, a maximum of 5.2 kW total TEM00-mode laser power was numerically extracted from 37 laser beams, averaging 141 W from each merged beam. The highest solar laser beam brightness figure of merit achieved was 148 W, corresponding to an improvement of 23 times in relation to the previous experimental record.

Hybrid Raman-Erbium Random Fiber Laser with a Half Open Cavity Assisted by Artificially Controlled Backscattering Fiber Reflectors

A hybrid Raman-erbium random fiber laser (RFL) with a half-open cavity assisted by chirped artificially controlled backscattering fiber reflectors (ACBFRs) is presented. A combination of 2.4 km of dispersion compensating fiber (DCF) with two highly erbium-doped fiber (EDF) pieces of 5 m length was used as gain medium. A single random laser emission line centered at 1553.8 nm with an output power level of -6.5 dBm and an optical signal to noise ratio (OSNR) of 47 dB was obtained when pumped at 37.5 dBm. A full width at half maximum (FHWM) of 1 nm and a 100% confidence level (CL) output power instability as low as 0.08 dB were measured. The utilization of the new laser cavity as a temperature and strain sensor is also experimentally studied.

Synchronization of pulsed and continuous-wave IMPATT oscillators in the millimeter wavelength range. Part 1. Generator designs and a generalized model of their external signal synchronization

Advances in the development of ultrahigh-frequency semiconductor electronics open wide opportunities for developing optimal schemes and designs of microwave power sources in the millimeter wavelength range providing high stability of the frequency and electromagnetic oscillation phase. Synchronized diode generators used in transmit/receive module for active phased array antennas, coherent low-power radar stations, etc. show great promise. The mode of external synchronization of semiconductor generators allows effectively implementing the task of creating output stages of the transmitters with high gain factor, low frequency noise and an output power level corresponding to the maximum power mode. This article presents the first of two parts of the study, which summarizes the results achieved so far in the development of synchronized oscillators based on impact ionization avalanche transit-time (IMPATT) diodes. The first part presents the electrodynamic designs of the oscillators, which are synchronized with an external source of microwave oscillations and contain a resonant oscillating system with a silicon IMPATT diode. The silicon two-drift IMPATT diode was chosen as an active element due to the fact that its use allows reaching significant levels of pulsed microwave power – an order of magnitude higher than those of the most well-known HEMT and pHEMT transistors in the millimeter wavelength range. It is shown that to reduce losses, the oscillating system should be made in the form of a radial resonator with a diode casing, which has distributed parameters. This eliminates the use of additional reactive inhomogeneities in the initial cross-section of the waveguide section of the generator. Due to the low quality factor of the resonant casing of the diode, the generalized quality factor of the microwave circuit takes the minimum value required to implement a stable generator synchronization process in the millimeter wavelength range. The second part of the work will be devoted to synchronized pulse generators with an output power of 20–150 W.

Synchronization of pulsed and continuous-wave IMPATT oscillators in the millimeter wavelength range. Part 2. Stabilizing microwave parameters of synchronized generators

This is the second part of the two-part article, which summarizes the state-of-the-art results in the development of synchronized oscillators based on IMPATT (IMPact ionization Avalanche Transit-Time) diodes. The first part of the paper presented the electrodynamic design of oscillators, which contain a resonant oscillatory system with silicon IMPATT diodes and are synchronized by an external source of microwave oscillations. The second part of the paper considers the methods for stabilizing the parameters of IMPATT oscillators, which make it possible to create coherent power sources in the millimeter wavelength range. The specifics of pulse generators lies in the change in frequency within the microwave pulse relative to the change in temperature, which leads to a change in the impedance of the diode and thus to a phase change with respect to the synchronizing signal. Phase modulation is reduced or completely eliminated (which is necessary to ensure the coherence of the microwave transmitter) by using current compensation, i.e., by using the control current pulse with a special shape. The study demonstrates the expediency of introducing additional heating of the semiconductor structure of the IMPATT diode, which allows the initial temperature of the IMPATT diode in the region of the leading edge of each pulse to remain virtually constant and independent of the ambient temperature. Using these methods on silicon double-drift IMPATT diodes allowed creating synchronized oscillators with high frequency stability and an output power level from 20 to 150 W, which have a high degree of coherence in the synchronization mode with an external signal. The paper also presents the designs and parameters of coherent microwave power sources in the short-wave part of the millimeter wavelength range using the nonlinear properties of the IMPATT diodes in the radio-pulse conversion mode. This mode makes it possible to provide the output power level of the signal at the n-th harmonic Pout ≈1/n, which significantly exceeds the achieved characteristics of the frequency multipliers with charge accumulation, where Pout ≈ 1/n2. The output power of such devices is achieved at the level of 50–20 mW in the 75–180 GHz frequency range with a frequency multiplication factor of 1–15.

Investigation of the electron-wave interaction process in the two-gap photonic crystal cavities of a low-voltage two barrel x-band multi-beam klystron.

This paper presents the results of comparing data from three-dimensional electromagnetic modeling of two designs of double-gap photonic crystal resonators of a two-barrel multi-beam klystron operating in the X-band at an accelerating voltage of 3.6 kV. These resonators are designed to operate on the main π-type oscillation with an output power level of about 2 kW. They are characterized by different profiles of the beam-let tubes. Each of the beam-let tubes in these structures contains 19 beam channels arranged in linear rows. The results of optimization of the complex of electronic and electro-dynamic parameters are presented. The optimal parameters and designs of resonant systems are found, which make it possible to significantly reduce the degree of inhomogeneity of the effective characteristic resistance in the interaction space.

Autonomous Energy Harvester Based on Textile-Based Enzymatic Biofuel Cell for On-Demand Usage

This paper presents an autonomous energy harvester based on a textile-based enzymatic biofuel cell, enabling an efficient power management and on-demand usage. The proposed biofuel cell works by an enzymatic reaction with glucose in sweat absorbed by the specially designed textile for sustainable and efficient energy harvesting. The output power of the textile-based biofuel cell has been optimized by changing electrode size and stacking electrodes and corresponding fluidic channels suitable for following power management circuit. The output power level of single electrode is estimated less than 0.5 μW and thus a two-staged power management circuit using intermediate supercapacitor has been presented. As a solution to produce a higher power level, multiple stacks of biofuel cell electrodes have been proposed and thus the textile-based biofuel cell employing serially connected 5 stacks produces a maximal power of 13 μW with an output voltage of 0.88 V when load resistance is 40 kΩ. A buck-boost converter employing a crystal oscillator directly triggered by DC output voltage of the biofuel cell makes it possible to obtain output voltage of the DC–DC converter is 6.75 V. The efficiency of the DC–DC converter is estimated as approximately 50% when the output power of the biofuel cell is tens microwatts. In addition, LT-spice modeling and simulation has been presented to estimate power consumption of each element of the proposed DC–DC converter circuit and the predicted output voltage has good agreement with measurement result.