Method and apparatus for optical signal transmission
View Patent ↗A method and apparatus for transmission of optical signals across an optical transmission link wherein duobinary signals or inverse-data signals are transmitted when the chromatic dispersion of the transmission link is above or below a dispersion threshold, respectively, to significantly improve optical signal transmission performance.
1. A method for transmitting optical signals across a transmission link comprising the steps of:
generating in an optical modulator, the optical signals based upon the chromatic dispersion of the transmission link, wherein the generated optical signals are duobinary signals if the chromatic dispersion of the transmission link is above a predetermined dispersion threshold D th , else inverse-data signals if the chromatic dispersion of the transmission link is below the predetermined dispersion threshold D th ; and
transmitting the generated optical signals across the transmission link,
wherein D th is determined according to the following relationship,
D
th
=
700
ps
nm
(
10
Gb
/
s
BR
)
2
,
and BR is the bit-rate of the transmitted optical signals.
2. A method for generating optical signals for transmission across a transmission link comprising the steps of:
driving an optical modulator to generate the optical signals based upon the chromatic dispersion of the transmission link, wherein the driving step farther includes the steps of;
controlling the bias of the modulator based on the chromatic dispersion of the transmission link, such that the modulator is biased at peak if the chromatic dispersion of the transmission link is below a predetermined dispersion threshold D th , else the modulator is biased at a null if the chromatic dispersion of the transmission link is above the predetermined dispersion threshold D th ; and
generating an inverse-data signal waveform if the modulator is biased at the peak, else generating a duobinary signal waveform if the modulator is biased at the null,
wherein D th is determined according to the following relationship,
D
th
=
700
ps
nm
(
10
Gb
/
s
BR
)
2
,
and BR is the bit-rate of the transmitted optical signals.
3. A method for generating optical signals for transmission across transmission link comprising:
driving a dual output modulator to generate duobinary signals at a first output port and inverse-data signals at a second output port; and
controlling an optical switch coupled to the modulator based upon the chromatic dispersion of the transmission link to select between transmitting the duobinary signals from the first output port across the transmission link and transmitting the inverse-data signals from the second output port across the transmission link.
4. An apparatus for transmitting optical signals across a transmission link comprising:
an optical modulator for generating optical signals based upon the chromatic dispersion of the transmission link; and
a bias control apparatus for controlling the bias of the modulator based upon the chromatic dispersion of the transmission link,
such that the waveform of the generated optical signals has a duobinary signal waveform if the chromatic dispersion of the transmission link is above a predetermined dispersion threshold D th , else has an inverse-data signal waveform if the chromatic dispersion of the transmission link is below the predetermined dispersion threshold D th ,
wherein D th is determined according to the following relationship,
D
th
=
700
ps
nm
(
10
Gb
/
s
BR
)
2
,
and BR is the bit-rate of the transmitted optical signals.
5. The apparatus of claim 4 wherein the bias control apparatus includes:
a control unit for generating a bias control signal based on the chromatic dispersion of the transmission link; and
a bias control coupled to the control unit and the modulator such that based on the bias control signal generated by the control unit, the bias control apparatus sets the bias of the modulator to null if the chromatic dispersion of the transmission link is above a predetermined dispersion threshold D th , else to peak if the chromatic dispersion of the transmission link is below the predetermined dispersion threshold D th .
6. An apparatus for transmitting optical signals across a transmission link comprising:
an optical modulator for generating duobinary signals at a data output port and inverse-data signals at an inverse-data output port;
an optical switch coupled to the data and inverse-data output ports of the modulator for selecting between transmission of the duobinary signals from the data output port and transmission of the inverse-data signals from the inverse-data output port; and
a controller for controlling the optical switch based upon the chromatic dispersion of the transmission link.
7. An apparatus for transmitting optical signals across a transmission link comprising:
means for generating optical signals based upon the chromatic dispersion of the transmission link, wherein the generated optical signals are optical duobinary signals if the chromatic dispersion of the transmission link is above a predetermined dispersion threshold D th , else optical inverse-data signals if the chromatic dispersion of the transmission link is below the predetermined dispersion threshold D th ; and
means for transmitting the generated optical signals across the transmission link
wherein D th is determined according to the following relationship,
D
th
=
700
ps
nm
(
10
Gb
/
s
BR
)
2
,
and BR is the bit-rate of the transmitted optical signals.