Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
2000-04-03
2001-11-27
Pascel, Leslie (Department: 2733)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200
Reexamination Certificate
active
06323976
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light source for frequency division multiplexed communications for use in optical communications.
2. Background Art
Among conventional light source devices having a plurality of semiconductor lasers which output light of different frequencies, one known method for stabilizing the optical frequencies of the semiconductors is to provide a plurality of semiconductor lasers having different output frequencies and a plurality of Fabry-Perot etalon resonators corresponding to these semiconductor lasers, then using the optical frequency discrimination capabilities of Fabry-Perot etalon resonators to control the drive currents of the semiconductor lasers by feedback of the outputs of the corresponding Fabry-Perot etalon resonators.
However, such conventional light source devices for frequency division multiplexed optical communications as described above use a separate Fabry-Perot etalon resonator for each optical frequency to be stabilized, as a result of which the devices can become massive and the production costs can rise.
SUMMARY OF THE INVENTION
The present invention has been made in view of this background art, and has the object of offering a light source device for frequency multiplexed optical communications which can be made more compact and at a reduced cost.
The present invention comprises a plurality of light sources for outputting light having optical frequencies which oscillate at mutually different modulation frequencies centered about mutually different optical frequencies; a plurality of splitting means corresponding to the respective light sources, each splitting means being provided for splitting output light from a corresponding light source into two parts, and outputting one part to an output end; multiplexing-splitting means for multiplexing the other parts of the light outputted by the plurality of splitting means, and splitting the multiplexed light into two outputs; transmitting means for transmitting the respective components of light in the first output of the multiplexing-splitting means at specified transmission rates corresponding to the optical frequencies of the components of light; first light receiving means for detecting the output light transmitted by the transmitting means; second light receiving means for detecting the second output of the multiplexing-splitting means; a plurality of transmission rate change detecting means corresponding to the respective light sources, each transmission rate change detecting means being provided for detecting an amount of change in transmission rate of the transmitting means at the optical frequency of a corresponding light source, from the frequency component at the modulation frequency of the corresponding light source in the output signal of the first light receiving means and the frequency component at the modulation frequency of the corresponding light source in the output signal of the second light receiving means; and control means for controlling the plurality of light sources by feedback such as to maximize the outputs of the plurality of transmission rate change detecting means.
Additionally, the present invention comprises a plurality of light sources for outputting light having optical frequencies which oscillate at mutually different modulation frequencies centered about mutually different optical frequencies; a plurality of splitting means corresponding to the respective light sources, each splitting means being provided for splitting output light from a corresponding light source into two parts, and outputting one part to an output end; multiplexing means for multiplexing the other parts of the light outputted by the plurality of splitting means; transmitting means for transmitting the respective components of light in the output of the multiplexing means at specified transmission rates corresponding to the optical frequencies of the components of light; light receiving means for detecting the output light transmitted by the transmitting means; and a plurality of control means corresponding to the respective light sources, each control means being provided for phase-detecting the frequency component at the modulation frequency of a corresponding light source in the output signal from the light receiving means with a signal of the modulation frequency as a reference signal, and controlling the corresponding light source by feedback such that the output of the phase detection is held at zero.
The present invention enables the size and cost of devices to be reduced by enabling the central frequencies of light outputted by a plurality of light sources to be fixed at respectively different or identical optical frequencies, using the frequency discriminating properties of a single Fabry-Perot etalon resonator, by modulating the optical frequencies of light outputted from a plurality of light sources by respectively different modulation frequencies.
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Ando Electric Co. Ltd.
Darby & Darby
Pascel Leslie
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