Optics: measuring and testing – For optical fiber or waveguide inspection
Reexamination Certificate
2000-05-12
2003-12-09
Nguyen, Tu T. (Department: 2877)
Optics: measuring and testing
For optical fiber or waveguide inspection
Reexamination Certificate
active
06661503
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a transmitter module, a receiver module, etc. employed to compose a light transmission system at a high yield, and inspecting each of those modules for a character of its low bit error rate (BER: a bit error rate of a signal output from a receiver to the number of random patterns of a signal entered to a transmitter or a disagreement rate of a signal pattern output from the receiver to a signal pattern entered to the transmitter) quickly and accurately with respect to a propagated optical power, as well as a system and a method for inspecting those manufactured modules easily, quickly, and accurately. More particularly, the present invention relates to inspection of optic transmission modules employed for composing a light transmission system for such characters as minimum received power sensitivity, dependency of an optical power by rate, propagation penalty, etc., that is, techniques for measuring, inspecting, and testing fast light/electrical signals.
2. Description of Related Art
To measure a character of a bit error rate (BER), which is the first related art technique, an error rate measuring instrument is used in accordance to the object propagation velocity. In this case, the number of errors is counted and the error rate is calculated within a predetermined time of a received signal light both when the transmitter and the receiver are directly connected to each other and when they are connected to each other via a long distance fiber line. It is premised here that both transmitter and receiver are not disturbed by any interference light. Usually, it takes about ten minutes per BER curve to measure a BER character of about 10
−3
to 10
−12
. In addition, because such a BER curve must be measured according to the fluctuation of the ambient temperature and the fluctuation of the power supply of the transmission/receiver module, it takes about a few hours to inspect each object module.
Furthermore, because it takes a few hours to several tens of hours to measure a BER character whose order is as low as 10
−13
and 10
−14
, it is confirmed that no error occurs in bit error measurements at an optical power, which is a few dBm higher than an optical power when the BER character of 10
−10
is obtained with addition of an interference light employed as one-point data.
The second related art technique is a sinusoidal wave interference method, which is disclosed in the document (Margin Measurements in Optical Amplifier Systems: IE3 PHOTONICS TECHNOLOGY LETTER, VOL.5, NO.3, MARCH 1993). According to this method, both amplitude and BER of a sinusoidal wave signal are used for extrapolating the BER, so that the extrapolation comes to be possible for up to about 10
−20
.
The third related art technique is a method for measuring a bit error rate with addition of a noise, thereby calculating and estimating a bit error rate when no degradation is recognized, as disclosed in Japanese Published Unexamined Patent Application No.6-252959. In this method, a relative phase of a demodulated output is identified both before and after a noise is added, thereby calculating the BER.
In recent years, however, it has been demanded to measure a lower bit error rate of 10
−12
or under, since information communication systems are getting faster and faster in operation and larger and larger in capacity so as to meet the requirement of a higher reliability of fast optical communication systems.
The first related art technique, however, has been confronted with problems that it takes a long time to a non-actual extent, as well as a predetermined accuracy cannot be guaranteed for the result.
The second related art technique has also been confronted with problems that a predetermined accuracy cannot be guaranteed in inspection, since a sinusoidal wave signal must be changed in amplitude and modified, thus difficult to be controlled. In addition, it would take more than a thousand year to confirm an extrapolation accuracy and a relative error in the conventional measurement in real time on the level of 10
−20
.
The third related art technique has also been confronted with a problem that a predetermined accuracy cannot be guaranteed in inspection, since the identification process is too complicated.
SUMMARY OF THE INVENTION
Under the circumstances, it is an object of the present invention to provide a method for manufacturing optic transmission modules, which can assure a high reliability for each of those optic transmission modules in quick and accurate inspection of the character of its low bit error rate (BER) so as to be employed satisfactorily for an optical communication system (a light transmission system) required to cope with information communication systems that are getting faster and faster in operation and larger and larger in capacity, thereby solving the above related art problems, as well as a system and a method for inspecting the character of such a bit error rate (BER).
It is another object of the present invention to provide a method for manufacturing high quality optic transmission modules at a high yield by quick and accurate inspection each of those optic transmission modules with respect to the character of its low bit error rate (BER) so as to be employed satisfactorily for an optical communication system (light transmission system) required to cope with information communication systems that are getting faster and faster in operation and larger and larger in capacity.
In order to achieve the above objects, the method of the present invention for manufacturing optic transmission modules comprises the processes of;
(A) manufacturing an optic transmission module employed for a light transmission system; and
(B) inspecting the optic transmission module manufactured in the manufacturing process for a character of its bit error rate with use of a bit error rate specific inspection system; wherein
the bit error rate specific inspection system includes;
signal light transmitting means for generating a light signal according to an electrical signal pattern;
interference light transmitting means for generating an interference light according to a disturbance signal having a rectangular pulse waveform;
a light coupler for mixing the signal light received from the signal light transmitting means optionally with the interference light received from the interference light transmitting means;
optical means for changing the optical power of the mixed light received from the light coupler;
receiving means for converting the mixed light received from the optical means to an electrical signal so as to be identified and regenerated; and
calculating means for measuring a bit error rate of the mixed signal regenerated by the receiving means corresponding to the optical power of the mixed light changed by the optical means, thereby calculating a character of a bit error rate of a signal light to its optical power according to this measured bit error rate corresponded to the change of the optical power of the mixed light, then generating a character of a bit error rate when no interference light is detected on the basis of a theoretical character of a bit error rate according to this calculated character of the bit error rate of the signal light to its optical power so as to be inspected.
Furthermore, in order to achieve the above objects, the method of the present invention for:manufacturing optic transmission modules comprises the processes of;
(A) manufacturing an optic transmission module employed for a light transmission system; and
(B) inspecting a character of a bit error rate of the optic transmission module manufactured in the manufacturing process with use of a bit error rate specific inspection system; wherein
the bit error rate specific inspection system includes;
signal light transmitting means for generating a light signal according to an electrical signal pattern;
interference light transmitting means for generating an interference
Aoyama Kazuo
Baba Naohiko
Kawamoto Kazumi
Minato Takashi
Murata Atsushi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Nguyen Tu T.
LandOfFree
Method for manufacturing optic transmission modules and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing optic transmission modules and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing optic transmission modules and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3139395