Active optical loop-back system

Details Active optical loop-back system Active optical loop-back system

1998-03-12

2001-06-12

Pascal, Leslie (Department: 2633)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S199200, C359S199200, C359S199200

Reexamination Certificate

active

06246497

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to optical communication systems. More particularly, this invention relates to a method and apparatus for looping-back an optical signal used in optical communications.
2. The Prior Art
Continuity of optical fiber transmission lines is often tested using an Optical Time Domain Reflectometer (OTDR), which sends an optical signal into an optical fiber and then senses any reflections off of discontinuities, such as breaks, returning on the optical fiber to the OTDR. Use of an OTDR interrupts the normal transmission of data and does not allow for diagnostic analysis of other aspects of an optical network during the OTDR tests. Furthermore, OTDRs are expensive pieces of test equipment. Therefore, cost limitations prevent the simultaneous use of OTDRs on many different transmission lines of an optical network. Furthermore, OTDR detection of signal discontinuities may be difficult due to normal attenuation of the OTDR signal in the case of long transmission lines. OTDR's also have the disadvantage of not being able to perform several important functions, including: testing transmission line integrity; performing round trip performance analysis; injecting and detecting errors; and, testing higher communications layers.
Loop-back, in which a signal is sent down one optical fiber and returned on another optical fiber, is a less costly method of detecting discontinuities than using OTDR's. However, conventional loop-back systems require the entire transmission line be dedicated to the loop-back process during a discontinuity test or a performance test. Furthermore, loop-back tests are limited in range due to the fact that the test beam may be significantly attenuated due to the added optical path length introduced in the loop-back process.
Nowhere does the prior art disclose a method or apparatus for employing loop-back in a discontinuity test that allows continued use of the transmission line for the transmission of data and that uses normal data for the discontinuity test and that regenerates the test beam.
SUMMARY OF THE INVENTION
The above-noted disadvantages of the prior art are overcome by the present invention, which in one aspect is an apparatus for looping-back an optical signal in an optical communications system that includes a transmitting station and a receiving station optically coupled to the transmitting station by a transmission fiber and reception fiber. Data is transmitted from the transmitting station to the receiving station through the transmission fiber and is also transmitted from the receiving station to the transmitting station through the reception fiber. The apparatus includes a beam splitter having an input port, an output port and a tap port, operationally coupled to the transmission line. The beam splitter is capable of diverting a preselected beam portion of an optical data beam being transmitted through the transmission fiber to the tap port. A tap fiber that is operationally coupled to the tap port allows the preselected beam portion to propagate therethrough. An optical analyzer, optically coupled to the tap fiber, regenerates the preselected portion, thereby creating a return beam. A return fiber, optically coupled to the optical analyzer, transmits the return beam. An optical switch, optically coupled the to reception fiber and to the return fiber, selectively optically couples the return fiber to the transmitting station through the reception fiber and selectively decouples the return fiber from the transmitting station. A switch controller, operationally coupled to the optical switch, causes the optical switch to optically couple the return fiber to the reception fiber.
In another aspect, the invention is a method of generating a loop-back test on an optical communications channel, including a transmission fiber and a reception fiber. A signal from a transmitting station is transmitted into the transmission fiber. a portion of a signal transmitted through the transmission fiber is tapped from the transmission fiber, thereby creating a tapped signal. The tapped signal is regenerated with an optical analyzer, thereby generating a regenerated signal. The regenerated signal is introduced into the reception fiber and the regenerated signal is received at the transmitting station.
An advantage of the invention is that it allows loop-back tests to be performed with actual data. A further advantage of the invention is that it allows analysis of data being looped-back. A further advantage of the invention is that it allows loop-back tests to be performed with minimal additional hardware expenditure.
These and other advantages will become apparent from the following description of the preferred embodiment taken in conjunction with the following drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure.


REFERENCES:
patent: 4313224 (1982-01-01), Wakabayashi et al.
patent: 4534064 (1985-08-01), Giacometti et al.
patent: 4829512 (1989-05-01), Nakai et al.
patent: 5274496 (1993-12-01), Fujiwara et al.
patent: 5282074 (1994-01-01), Miyazaki et al.
patent: 5296957 (1994-03-01), Takahashi et al.
patent: 5301050 (1994-04-01), Czerwiec et al.
patent: 5319482 (1994-06-01), Tsuchiya et al.
patent: 5335104 (1994-08-01), Johnson
patent: 5381257 (1995-01-01), Ferrar
patent: 5528404 (1996-06-01), MacKichan
patent: 5539558 (1996-07-01), Yonemura et al.
patent: 5557437 (1996-09-01), Sakai et al.
patent: 5615034 (1997-03-01), Hori
patent: 5677781 (1997-10-01), Mori et al.
patent: 6023359 (2000-02-01), Asahi

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