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公开(公告)号：DE69601835D1
公开(公告)日：1999-04-29
申请号：DE69601835
申请日：1996-06-28
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
Abstract: An optical fiber amplifier comprising, in addition to an amplification medium for amplifying signal light, an excitation light source which generates excitation light to be launched into the amplification medium and photocoupling means for coupling the excitation light to the amplification medium, modulating means for amplitude-modulating the excitation light, sub-signal generating means for generating a sub-signal which is superimposed on the excitation light for amplitude modulation and a frequency filter for converting the frequency characteristic of the sub-signal to input it to the modulating means, for superimposing the sub-signal due to change in gain of the amplification medium for pulse modulation of the excitation light. High-frequency components of the sub-signal is previously emphasized through the frequency filter, and the excitation light is amplitude-modulated by the sub-signal with the emphasized high-frequency components, to superimpose the satisfactory, waveform distortion-free sub-signal on the signal light.
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公开(公告)号：FR2776440A1
公开(公告)日：1999-09-24
申请号：FR9903310
申请日：1999-03-17
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
IPC: H04B10/038 , H04B10/071 , H04B10/25 , H04B10/08 , H04B10/16
Abstract: The circuit enables reflection wavelengths and values to be monitored from a central system location using a by-pass surveillance circuit. The by-pass circuit (32) of a supervision light signal has a first optical coupler (32a) on a first optical transmission line (31a), a second optical coupler (32b) on a second optical transmission line (31b) along which the light signal is transmitted in a direction opposite to the first optical transmission line. A third optical transmission line is connected to an exit terminal of the first optical coupler and an exit terminal of the second optical coupler. A first reflection element which is provided on another exit terminal of the first coupler, producing a first reflection wavelength, and a second reflection element is provided on another exit terminal of the second optical coupler at a second reflection wavelength.
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公开(公告)号：FR2737827A1
公开(公告)日：1997-02-14
申请号：FR9609966
申请日：1996-08-07
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
IPC: H04J14/00 , H04B10/07 , H04B10/2507 , H04B10/27 , H04B10/29 , H04B10/293 , H04B10/564 , H04B10/572 , H04J14/02
Abstract: A wavelength division multiplexing transmission system includes a light transmitter (20, 20A), a light receiver (30), and an optical transmission path (40) for connecting the light transmitter and the light receiver. The wavelength division multiplexing transmission system also includes a feedback section (80) for connecting to the light receiver and the light transmitter. The light receiver has a power level detecting unit (36) which detects received light power levels of demultiplexed light signals to produce detected light power level signals. An encoding unit (37) encodes the detected light power level signals into an output light power level signal. The feedback section therefore transmits the output light power level signal as a transmission light power level signal from the light receiver to the light transmitter. The light transmitter includes a decoding circuit (27) for decoding the transmission light power level signal into input light power level signals as replicas of the detected light power level signals. A power control unit (24, 24A) is responsive to the input light power level signals to control light sources (22-1 to 22-m) to change controllable original light power levels of original light signals so that the demultiplexed light signals have the received light power levels each of which becomes a predetermined light power level.
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公开(公告)号：GB2299232A
公开(公告)日：1996-09-25
申请号：GB9606035
申请日：1996-03-22
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
Abstract: The optical regenerator receives an input signal 21 which is divided by coupler 11. One divided signal 21B acts as an input to an optical clock generator 12 whose output is used by optical discriminator 14 (basically an AND gate) to retime the other divided signal 21A. In order to compensate for propagation times, an adjustable delay 13 is inserted before or after clock generator 12 or before discriminator 14. Variable delay circuit may comprise a number of optical fibres of different lengths one of which is selected (fig 3, fig 6) or a single fibre wrapped around two semicircular blocks which may be separated to stretch the fibre (fig 7).
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公开(公告)号：DE69627959T2
公开(公告)日：2003-11-27
申请号：DE69627959
申请日：1996-10-29
Applicant: NEC CORP
Inventor： AOKI YASUHIRO , OGATA TAKAAKI , YONEYAMA KENICHI , MICHISHITA YUKIO , SATO YOSHIRO
Abstract: Optical surge preventing systems and methods for rare earth-doped optical fiber amplifiers are disclosed. The systems are so arranged as to cause any signal exist in a doped fiber section so as not to excite too much the rare earth elements in the doped fiber section. In one embodiment, a background signal light with such a wavelength as to cause induced emission in the doped fiber section is always coupled into the doped fiber section regardless of whether a message signal light exists or not. The background signal light may be generated by any suitable light source or a light spontaneously emitted from either end of the doped fiber section. In another embodiment, a dummy signal light is coupled into the doped fiber section if the level of the message signal light becomes less than a predetermined value. Coupling of the background signal light or the dummy signal light into the doped fiber section may be done from either of the message signal input and output sides.
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Patent Agency Ranking
公开(公告)号：DE69627959D1
公开(公告)日：2003-06-12
申请号：DE69627959
申请日：1996-10-29
Applicant: NEC CORP
Inventor： AOKI YASUHIRO , OGATA TAKAAKI , YONEYAMA KENICHI , MICHISHITA YUKIO , SATO YOSHIRO
Abstract: Optical surge preventing systems and methods for rare earth-doped optical fiber amplifiers are disclosed. The systems are so arranged as to cause any signal exist in a doped fiber section so as not to excite too much the rare earth elements in the doped fiber section. In one embodiment, a background signal light with such a wavelength as to cause induced emission in the doped fiber section is always coupled into the doped fiber section regardless of whether a message signal light exists or not. The background signal light may be generated by any suitable light source or a light spontaneously emitted from either end of the doped fiber section. In another embodiment, a dummy signal light is coupled into the doped fiber section if the level of the message signal light becomes less than a predetermined value. Coupling of the background signal light or the dummy signal light into the doped fiber section may be done from either of the message signal input and output sides.
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公开(公告)号：DE69601835T2
公开(公告)日：1999-10-21
申请号：DE69601835
申请日：1996-06-28
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
Abstract: An optical fiber amplifier comprising, in addition to an amplification medium for amplifying signal light, an excitation light source which generates excitation light to be launched into the amplification medium and photocoupling means for coupling the excitation light to the amplification medium, modulating means for amplitude-modulating the excitation light, sub-signal generating means for generating a sub-signal which is superimposed on the excitation light for amplitude modulation and a frequency filter for converting the frequency characteristic of the sub-signal to input it to the modulating means, for superimposing the sub-signal due to change in gain of the amplification medium for pulse modulation of the excitation light. High-frequency components of the sub-signal is previously emphasized through the frequency filter, and the excitation light is amplitude-modulated by the sub-signal with the emphasized high-frequency components, to superimpose the satisfactory, waveform distortion-free sub-signal on the signal light.
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公开(公告)号：GB2299232B
公开(公告)日：1999-06-09
申请号：GB9606035
申请日：1996-03-22
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
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公开(公告)号：FR2756688A1
公开(公告)日：1998-06-05
申请号：FR9715305
申请日：1997-12-04
Applicant: NEC CORP
Inventor： YOSHIDA MASANORI , YONEYAMA KENICHI , TAURA TOHRU
IPC: H03L7/08 , H04B10/00 , H04B10/07 , H04B10/508 , H04B10/54 , H04B10/588 , H04L7/033 , H04B10/152
Abstract: The circuit includes a reference oscillator (103) for generating a reference signal which is offset by a multiple of the clock frequency. There is also a voltage controlled oscillator (110) for generating a clock signal. An optical system creates a difference component for the frequency difference between the operational frequency and the reference. A detector produces an electrical signal representing the difference frequency. A multiplier (107) creates a component for the frequency difference between the output signal of the reference oscillator, and the output of the voltage controlled oscillator. A phase detector compares the phase of the optical signal detector output with the multiplier output, to enable a control mechanism to supply a control voltage to the voltage controlled oscillator.
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公开(公告)号：FR2740282A1
公开(公告)日：1997-04-25
申请号：FR9612697
申请日：1996-10-18
Applicant: NEC CORP
Inventor： YONEYAMA KENICHI
IPC: H04B10/00 , H04B10/07 , H04B10/077 , H04B10/079 , H04B10/2507 , H04B10/27 , H04B10/29 , H04B10/54 , H04B10/548 , H04B10/564 , H04J14/02 , H04B10/12
Abstract: The method involves using a pair of transmission devices with ascending and descending optical fibres linking them together. Each transmission device includes a final transmission section (1a) comprising a number of light sources which can transmit signals with different wavelengths. An optical multiplexer (7,14) multiplexes the different wavelength signals. A reception section (2a) is provided at the remote end of the optical fibre. An optical divider (9) separates out the multiplexed light signals and an optical receiver (11) receives the separated signals which have different wavelengths. The distribution of optical power for the ascending and descending light signals are measured.
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