Optical waveguides – With optical coupler – Particular coupling function
Reexamination Certificate
1997-12-03
2001-03-06
Bovernick, Rodney (Department: 2874)
Optical waveguides
With optical coupler
Particular coupling function
C385S024000
Reexamination Certificate
active
06198859
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a dispersion compensating device using a dispersion compensating fiber module for compensating dispersion which is generated in a transmission line of optical fiber communication system.
Description of the Related Art
In the optical fiber communication system, the researches concerning speeding up of transmission rate and improvement of transmission characteristic are advanced in order to enlarge both transmission capacity and transmission distance. The optical fiber which is used as the transmission line of the optical fiber communication system has characteristic of wavelength dispersion that different wavelength of the signal light effects different propagation speed in answer to respective wave-length of signal light. In particular, a waveform distortion of an optical pulse caused by the wavelength dispersion maybe large, when the transmission speed is high speed for example, more than 1 Gb/s. Thus, the characteristic of transmission extremely deteriorates. A method is known for compensating for waveform distortion that results in a dispersion compensating fiber to be arranged. Such dispersion compensating fiber has the same dispersion quantity as the dispersion value corresponding to the transmission line, and has an inverse sign. Such dispersion compensating fiber is provided for the reception side.
However, the standard characteristic of the dispersion compensating fiber is that a dispersion value is −100 ps
m/km, and a loss factor is 0.8 dB/km. Consequently, when the transmission line becomes long, it is necessary to increase the length of the dispersion compensating fiber corresponding thereto. Because of these increased lengths, costs can become very high. For example, when the optical fiber whose dispersion value is +20 ps
m/km of 100 km is used, total dispersion quantity becomes 2000 ps
m, thereby the dispersion compensating fiber of 20 km is necessary to compensate thereof. Further, when the transmission line is 300 km, the dispersion compensating fiber of 60 km is required.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention for resolving the above-mentioned problem to provide a dispersion compensating device using a dispersion compensating fiber module which is capable of compensating the distortion of the optical pulse waveform caused by wavelength distortion using a low-priced constitution.
In accordance with one aspect of the present invention, for achieving the above-mentioned objectives, there is provided a dispersion compensating device which comprises a three port optical circulator having an input port, an intermediate port, and an output port in which a signal light inputted from the input port is transmitted to the intermediate port, then the signal light is transmitted from the intermediate port to the output port; a dispersion compensating fiber module with a first end section combined with the intermediate port of the optical circulator for compensating dispersion of the signal light by propagating the signal light therethrough; and a reflection means provided for a second end section of the dispersion compensating fiber module for reflecting the signal light by means of a totally internal, highly reflective surface thereof.
Preferably, the dispersion compensating fiber module comprises a dispersion compensating fiber whose first end face is combined with the intermediate port of the optical circulator while a second inside end face is formed by a totally internal, highly reflective surface.
Preferably, length of the dispersion compensating fiber is of one-half the length corresponding to necessary dispersion compensating quantity.
Preferably, the dispersion compensating fiber has a dispersion value of −95 ps
m/km, and a loss factor of 0.8 dB/km.
Preferably, the optical circulator has a passing loss of 1.2 dB.
Preferably, the second inside end face of the dispersion compensating fiber is coated with dielectric multilayer whose reflectance ratio is approximately 99.5%.
In accordance with another aspect of the present invention, there is provided a dispersion compensating method which comprises the steps of inputting a signal light to an input port of a optical circulator, transmitting the signal light to an intermediate port of the optical circulator, inputting the signal light to a dispersion compensating fiber which is combined with the intermediate port of the optical circulator, propagating the signal light through the dispersion compensating fiber for compensating dispersion of the signal light, reflecting the signal light into the dispersion compensating fiber by means of a totally internal, highly reflective surface so as to return to the intermediate port, and transmitting the signal light from the intermediate port to the output port.
The above and further objects and novel features of the invention will be more fully understood from the following detailed description when the same is read in connection with the accompanying drawings. It should be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limit of the invention.
REFERENCES:
patent: 4953939 (1990-09-01), Epworth
patent: 5037180 (1991-08-01), Stone
patent: 5404413 (1995-04-01), Delavaux et al.
patent: 5608562 (1997-03-01), Delavaux et al.
patent: 406276160A (1994-09-01), None
patent: 6-276160 (1994-09-01), None
patent: 8-204258 (1996-08-01), None
patent: 8-316912 (1996-11-01), None
patent: 8-288904 (1996-11-01), None
Japanese Office Action, dated Aug. 24, 1999, with English language translation of Japanese Examiner's comments.
Bovernick Rodney
McGuire Woods LLP
NEC Corporation
Stahl Michael J.
LandOfFree
Dispersion compensating device using dispersion compensating... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dispersion compensating device using dispersion compensating..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dispersion compensating device using dispersion compensating... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2475932