Optics: measuring and testing – By light interference – Spectroscopy
Reexamination Certificate
2000-08-10
2002-12-03
Turner, Samuel A. (Department: 2877)
Optics: measuring and testing
By light interference
Spectroscopy
Reexamination Certificate
active
06490042
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
This invention relates to a wave meter for measuring the wavelength of an optical signal multiplexed in WDM (Wavelength Division Multiplexing), etc.,
2. Description of the Related Art
In recent years, developments in the information communication field typified by the Internet, portable telephones, etc., have been remarkable, and the amount of information on a transmission line has been dramatically increased accordingly. An optical fiber can be named as one of the transmission lines supporting the information communication field as the core therefor. Optical fiber cables are already laid in the ground and on the seal bottom and are actually used. However, to cope with a rapid increase in the communication traffic, means for enabling high-speed and large-capacity transmission using the already existing optical fiber cables is demanded in addition to installation of additional optical fiber cables. WDM technology is one of the means.
The WDM is a system using the property of light having one wavelength not interfering with light having a different wavelength to transmit a plurality of optical signals different in wavelength at the same time, thereby using one optical fiber in a multiplexing manner. In a conventional system using a single wavelength, a transmission capacity of 2.5 to 10 Gbps is a limit; however, the WDM can provide a transmission capacity at a terabit level by performing 128 multiplexing of signal transmitted at 10 Gbps, for example.
To put the transmission using the WDM, which will be hereinafter called WDM transmission, to use, a machine for evaluating the transmission characteristic at the WDM transmission time with high precision is required. Then, a wave meter called an optical spectrum analyzer for measuring and analyzing the spectra of a plurality of optical signals is developed as such a machine.
Hitherto, such a wave meter has not been provided with a function of monitoring the communication state during the WDM transmission and issuing a warning if an abnormal state is detected. However, if the wavelength of an optical signal, etc., varies beyond the range in the specifications in the WDM transmission, the signal quality in the reception section is degraded remarkably. Thus, it is necessary to monitor multiplexed optical signal in the WDM transmission with a plurality of optical signals multiplexed.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a wave meter for monitoring optical signals multiplexed in WDM transmission, etc.
According to a first aspect of the invention, there is provided a wave meter for measuring transmitted signal light comprising a plurality of optical signals multiplexed by a predetermined system (for example, WDM), the wave meter comprising:
reference setting means (for example, CPU
6
in
FIG. 1
; step S
2
in
FIG. 4
) for setting a measurement reference of the signal light based on the predetermined system;
variation amount setting means (for example, CPU
6
in
FIG. 1
; step S
1
in
FIG. 4
) for setting an allowable variation amount of the signal light at the transmission time;
measurement means (for example, CPU
6
in
FIG. 1
; step S
3
in
FIG. 4
) for continuously measuring the transmitted signal light; and
determination means (for example, CPU
6
in
FIG. 1
; step S
4
in
FIG. 4
) for determining whether or not the measurement result of the signal light provided by the measurement means is within the range of the allowable variation amount set by the variation amount setting means relative to the measurement reference set by the reference setting means, characterized in that
if the determination means does not determine that the signal light is within the range of the allowable variation amount relative to the measurement reference, an anomaly of the signal light is detected.
According to the first aspect of the invention, in the wave meter for measuring transmitted signal light comprising a plurality of optical signals multiplexed by a predetermined system, the reference setting means sets a measurement reference of the signal light based on the predetermined system, the variation amount setting means sets an allowable variation amount of the signal light at the transmission time, the measurement means continuously measures the transmitted signal light, the determination means determines whether or not the measurement result of the signal light provided by the measurement means is within the range of the allowable variation amount set by the variation amount setting means relative to the measurement reference set by the reference setting means, and if the determination means does not determine that the signal light is within the range of the allowable variation amount relative to the measurement reference, an anomaly of the signal light is detected.
Whether or not the signal light continuously measured by the measurement means is within the range of the allowable variation amount relative to the measurement reference is determined, so that a wave meter for checking whether or not transmission is executed within the range in the specifications of the predetermined system can be provided, for example.
According to a second aspect of the invention, in the wave meter of the first aspect, the reference setting means may set the measurement reference of each of the optical signals multiplexed into the signal light,
the variation amount setting means may set the allowable variable amount of each of the optical signals multiplexed into the signal light,
the measurement means may continuously measure the transmitted signal light and determines each of the optical signals multiplexed into the signal light, and
the determination means may determine whether or not each optical signal determined by the measurement means is within the range of each corresponding allowable variation amount set by the variation amount setting means relative to each corresponding measurement reference set by the reference setting means.
According to the second aspect of the invention, in addition to the advantage of the first aspect of the invention, each of the optical signals multiplexed is monitored, so that more detailed monitor can be executed for determining an optical signal in which an anomaly occurs, for example, and a message indicating the fact can be displayed. In this case, various actions can be taken; for example, the abnormal optical signal is removed, only the normal optical signals are multiplexed, and the transmission is continued.
According to a third aspect of the invention, in the wave meter of the second aspect, the reference setting means may set the power amount (power) of each optical signal as the measurement reference of each of the optical signals multiplexed into the signal light, and
the variation amount setting means may set the allowable variation amount of the power amount of each of the optical signals multiplexed into the signal light.
According to a fourth aspect of the invention, in the wave meter of the second aspect, the reference setting means may set the wavelength of each optical signal as the measurement reference of each of the optical signals multiplexed into the signal light, and
the variation amount setting means may set the allowable variation amount of the wavelength of each of the optical signals multiplexed into the signal light.
In the third or fourth aspect of the invention, the measurement reference and the allowable variation amount are the power amount or the wavelength of each optical signal. Thus, it is made possible to set the measurement reference and the allowable variation amount using a waveform graph of optical signal with the power amount on the vertical axis and the wavelength on the horizontal axis, for example.
Further, according to a fifth aspect of the invention, in the wave meter of first to fourth aspects, the reference setting means may set the measurement reference of the signal light based on measurement reference light (for example, monitor reference wave) of signal light based on the p
Sasaki Shiori
Unno Yasushi
Ando Electric Co. Ltd.
Connolly Patrick
Fish & Richardson P.C.
Turner Samuel A.
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