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Volume 25, Issue 2
Displaying 1-16 of 16 articles from this issue
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Koichi SHIMODA1997 Volume 25 Issue 2 Pages 111
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
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Shoichi SUDO1997 Volume 25 Issue 2 Pages 112-113
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
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Minoru YOSHIDA1997 Volume 25 Issue 2 Pages 114-120
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe Er-doped fiber amplifier allows direct optical amplification with high pump to signal optical conversion efficiency. The amplifier for a 1.551.tm optical signal is compactly composed of an Er-doped fiber and other optical components. Amplification properties of the amplifier are mainly dependent on the Er doping concentration, the co-dopant, the fiber length, and the performance of the pumping power source. An optimized fiber, for use within the optical amplifier, has a gain of 40dB and a conversion efficiency of 85% from the incident pumping power to the amplified signal power. Amplification properties also depend on the characteristics of the optical signals. This paper explains techniques of structuring high-power Er-doped fiber amplifiers and recent high-power amplifiers.View full abstractDownload PDF (1376K) -
Takeshi IMAI, Masataka NAKAZAWA1997 Volume 25 Issue 2 Pages 121-125
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSAn erbium-doped fiber amplifier installed inside an optical fiber cable is reported. This optical cable amplifier is mechanically flexible as the result of using a flexible stainless steel tube and wire mesh as the amplifier cavity and outer cover, respectively. The amplifier is pumped with a 0.98μm laser diode to reduce both the electric driving power and the wavelength dependence of optical gain. Backward pumping is used to obtain a high optical output power. A gain of 27.5dB and a maximum optical output power of + 10dBm have been successfully realized. The wavelength dependence of the optical gain was 2.1dB between 1540nm and 1560nm. A two-channel optical cable amplifier with two EDFAs in the cable is also described. The noise figure of the amplifiers was approximately 6dB and the output power dependence on ambient temperature change was less than ±0.2dB between 20°C and 60°C.View full abstractDownload PDF (879K) -
Susumu KINOSHITA, Hiroshi ONAKA, Terumi CHIKAMA1997 Volume 25 Issue 2 Pages 126-130
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSWe review main subjects of wideband EDFAs and propose a novel wideband EDFA with a mid-attenuator for automatic level control operation. We confirm its expected performance in a 4-channel WDM experiment. Next, we explain that the ultra large capacity WDM transmission experiment. We obtained good BER characteristics for all channels by using pre-emphasis, wideband EDFAs and dispersion compensating fiber with a negative dispersion slope.View full abstractDownload PDF (1020K) -
Shinji YAMASHITA, Kazuo HOTATE1997 Volume 25 Issue 2 Pages 131-134
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSOptical fiber amplifiers offeres basically polarization-indenpendent gain. However, they have polarization fluctuation and polarization mode dispersion (PMD) due to birefringnence in fibers, and still have small polarization-dependent properties such as polarization hole burning (PHB) and polarization dependent loss (PDL). In this paper, these properties are reviewed. Compensation of these properties are also reviewed, with emphasis on the reflective fiber amplifier using Faraday rotator mirror (FRM).View full abstractDownload PDF (738K) -
Tetsuya MIYAZAKI1997 Volume 25 Issue 2 Pages 135-138
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA key point to develop the Nd-doped fiber amplifier (NDFA) at 1.06pm, the Al co-doping in the Nd-doped fiber, is introduced at first. After reviewing its basic amplification and noise characteristics, various possible application systems are discussed, such as fiber sensing, gravitational wave detection, free-space laser communication and laser radar, for both a booster amplifier and a preamplifier to improve the optical handling power in the transmitter and the sensitivity in the receiver. Finally, results of the fiber transmission and the tunable fiber ring laser source experiments, as examples of the application, are reported.The NDFA will offer a compact, high efficient, polarization independent and beam-distortion-free amplifier in stead of solid-state laser amplifiers at 1.06μm.View full abstractDownload PDF (643K) -
Yasutake OHISHI1997 Volume 25 Issue 2 Pages 139-146
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSFundamentals and status of development of PDFAs are described. An amplification mechanism model which expains PDFA perfromance is established. On the basis of the model efficient pump schemes are discussed in order to construct high performance amplifier modules. Performance of LD, Nd-YLF and MOPA-LD pumped PDFAs is presented. The gain efficiency of newly developed praseodymium-doped PbF2/InF3-doped fiber is described.View full abstractDownload PDF (1421K) -
Makoto YAMADA1997 Volume 25 Issue 2 Pages 147-152
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESS1.6μm band fiber amplifiers must be developed for future optical transmission line monitoring systems and ultra-wide band wavelength division multiplexing systems. The 1.6μm band Er3+-doped fiber amplifier (EDFA) and the Tm3+-doped fluoride fiber amplifier have been proposed as candidates. The former can be realized by shifting the amplification band of a 1.55μm band EDFA, by using a long Er3+-doped fiber. The latter employs the tail of the 1.8μm amplification band of Tm3+-doped fluoride fiber by the doping of terbium ions in the cladding. This paper reviews the amplification mechanisms and basic characteristics of 1.6μm band EDFAs and TDFAs.View full abstractDownload PDF (894K) -
Takeyuki KOBAYASHI, Keisuke SASAKI, Yasuhiro KOIKE1997 Volume 25 Issue 2 Pages 153-157
Published: February 15, 1997
Released on J-STAGE: July 30, 2010
JOURNAL FREE ACCESSIn quest of a high-power optical amplifier in the visible, we incorporated organic dyes into polymer optical fibers. Organic dyes were chosen as gain media based on the following features: a large emission cross section, which allows the achievement of high gains in a short length, and a broadband fluorescence spectrum that provides wide tunability. A Rhodamine B-doped POFA, 1 m in length and 0.3mm in core diameter, has exhibited more than 20dB gain at signal wavelengths from 560nm to 600nm when optically pumped at a wavelength of 532nm. Furthermore, we have obtained the optical amplification covering most of the spectral range from 560nm to 650nm. The spectral range in the visible can be continuously covered with the POFAs doped with several selected dyes. The broad spectral coverage demonstrates the versatility of the organic dye-doped POFA.View full abstractDownload PDF (798K) -
Motoki KAKUI, Tomonori KASHIWADA, Koji NAKAZATO, Masashi ONISHI, Masay ...1997 Volume 25 Issue 2 Pages 158-163
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSErbium-doped fiber amplifier (EDFA) featuring a spectrally flattened gain is considered to be one of the most important key devices for the wavelength-division multiplexing (WDM) transmission systems. For this purpose, we have developed hybrid EDFs composed of Al doped EDF and P/Al co-doped EDF and examined their characteristics comparing with the conventional EDFs and those with passive gain equalizers. As a result, hybrid EDFs have been shown to exhibit both a flat gain and high pumping efficiency, but their noise characteristics tends to be worse than conventional EDF configurations. Thus a midway isolator should be inserted. As a result of the design optimization, three-section hybrid EDF configuration has been proposed, and three types of EDFAs have been developed employing this configuration for use as in-line amplifiers or preamplifiers. All types exhibit the passband spanning about 15nm.View full abstractDownload PDF (1238K) -
Atsushi TOYOHARA, Hideki OKUNO, Masashi ITABASHI, Takefumi OGUMA, Jun ...1997 Volume 25 Issue 2 Pages 164-166
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThis paper discusses our EDFA module for multi-channel transmission systems. This EDFA module has flat gain characteristics in l5nm (from 1546 to 1561nm) and +20dBm signal output power. We improved gain flatness by optimizing EDF and using gain equalizers, which passively equalize gain variance of EDF.View full abstractDownload PDF (553K) -
Isamu OSHIMA, Yoshio TASHIRO, Akira FUJISAKI, Haruki OGOSHI1997 Volume 25 Issue 2 Pages 167-170
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESS1480nm band wavelength multiplexed semiconductor laser diode pump unit which has 600mW output power is developed. This pump unit applies to remote pumping system and high output power Er doped fiber amplifier. In remote pumping system, remotely pre-amplifier and remotely post-amplifier are demonstrated and 23.5dB of allowable optical transmission loss is improved. Raman gain is also discussed and 13.9dB Raman gain is obtained.2-stage Er doped fiber amplifier is constructed utilizing three pump units. Maximum output power is reached to +29.5dBm at 2nd stage Er doped fiber output end. Conversion efficiency of optical pump power to amplified optical signal power in Er doped fiber is 62.2%.View full abstractDownload PDF (640K) -
Yasushi FUJIMOTO, Masahiro NAKATSUKA1997 Volume 25 Issue 2 Pages 171-175
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA convenient method for quantum yield measurement is presented. An integrating sphere is arranged in a spectrometer system and thermopile energy calibration is employed. Although an absolute measurement is required for quantum yield, the thermopile energy calibration with the integrating sphere system is able to connect between absorbed and emitted energy from luminescent medium without absolute measurement for absorption and emission energies. In our new method, quantum yield is calculated from only four measured spectra and six voltages using the system and it can be measured over wide spectral range (0.25-2.5μm). The strict requirements for samples are reduced, e.g., polishing, scattering free, sample shape, the reproducibility is ±1.15% and the error is estimated ±6.84% over 400nm (±10.62% over 250nm).View full abstractDownload PDF (795K) -
Hiroshi TSUBAKIHARA, Takashi OKADA, Toyohiko ABE1997 Volume 25 Issue 2 Pages 176-178
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSWe investigate morphological changes produced by KrF excimer laser irradiation on polyimide surfaces, using different total fluences. Lower than 20 shots, very little roughness was introduced. With increasing shot numbers, however, surface structures were devided in two cases. Firstly, fibrous surface structure has been foned in crystallized polyimide. In second, spherical granular morphology has been foned in amorphous polyimide. The granular-size increasing with shot numbers should be explained by aggregation of laser-produced low molecular weight materials.View full abstractDownload PDF (730K) -
Kimihiro SHIBATA, Akira MATSUNAWA, Toshihiko OOIE, Sadao NAKAI1997 Volume 25 Issue 2 Pages 179-182
Published: February 15, 1997
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSDownload PDF (792K)
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