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Amplifier Gain (amplifier + gain)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

An overview on S-band erbium-doped fiber amplifiers

LASER PHYSICS LETTERS, Issue 1 2007
S. W. Harun
Abstract An erbium-doped fiber amplifier (EDFA) for S-band signal amplification is designed by using a depressed cladding erbium-doped fiber (DC-EDF). The fiber's characteristics are described in terms of the effects of the fiber spooling diameter on the amplifier's performance. In this experiment, the spooling diameter required for optimum amplifier gain was around 5,7 cm. By using a typical two-stage configuration (with a 27 m long DC-EDF and a 260 mW pump laser power), the maximum small signal gain obtained was about 32 dB. Yet, by employing a double pass amplifier configuration with a shorter DC-EDF length and a lower pump laser power (15 m and 135 mW, respectively), a similar maximum small signal gain of approximately 30 dB was achieved. This improvement in gain characteristics however, incurred an increased noise figure penalty of about 1 dB in comparison to single-pass amplifier configurations. In order to reduce the amplifier's noise figure while maintaining its high gain, a partial double-pass S-band EDFA configuration was introduced. This configuration provides a high 26.9 dB gain and an improved noise figure comparable to a single pass configuration. Gain clamping in S-band EDFAs are also demonstrated by utilizing a fiber Bragg grating to form an oscillating laser at around 1530 nm. This technique enables good gain clamping with a gain variation of less than 1 dB. (© 2007 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Experimental investigation into femtosecond fiber ring laser with passive mode locking

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2009
Xiaoping Xie
Abstract A passively mode-locked Er3+ -doped fiber ring laser is experimentally investigated, with the emphasis on its practical design by considering the effects of ring cavity length, pumping light power, and optical amplification on the femtosecond optical pulses obtained. It is shown that the designed fiber ring laser can operate at the center wavelength of 1550 nm to produce a train of periodic optical pulses with full width at half maximum (FWHM) of 270 fs, repetition frequency of 20 MHz, and average output optical power of 146 ,W. The resulting femtosecond optical pulses are then amplified by using three kinds of Er3+ -doped optical fibers with different lengths and Er3+ -doped concentrations, respectively, while employing the same pumping laser. In the experiments, both the FWHM of amplified optical pulses and the amplifier gain are measured under different conditions. The optimization of optical pulse width is also carried out in terms of pumping light power. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 63,67, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23985 [source]

Stability analysis of the constant temperature anemometer with frequency depended amplifier gain

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003
ajn M.Sc.
In this paper we are concerned with the stability and the dynamic response of the constant temperature anemometer. The amplifier of the presented hot,wire anemometer has one pole with high time constant, which affect the presented amplifier to behave in the anemometer working frequency bandwidth with the frequency depended gain. For precise description of the anemometer dynamical response the used transfer function of the amplifier is first order of zeros and third order of poles. The hot,wire response to the sine-wave voltage perturbation was calculated and measured. The root curves of the transfer function were presented. [source]

FORCE RIPPLE COMPENSATION OF LINEAR SYNCHRONOUS MOTORS

ASIAN JOURNAL OF CONTROL, Issue 1 2005
Christof Röhrig
ABSTRACT Linear synchronous motors are finding expanded use in high-performance applications where high speed and high accuracy is essential. The main problem in improving the tracking performance of linear synchronous motors is the presence of force ripple caused by mismatched current waveforms and unbalanced motor phases or amplifier gains. This paper presents a method to optimize the waveform of the phase currents in order to generate smooth force. The optimized current waveforms produces minimal copper losses and maximize motor efficiency. The waveforms are implemented in a waveform generator of the motion controller and approximated with Fourier series. The optimization method consist of three stages. In every stage, different harmonics of the force ripple are reduced. A comparison of the tracking performance with optimized waveforms and with sinusoidal waveforms shows the effectiveness of the proposed method. [source]