100 Gbit/s OFDM optical signal generation
View Patent ↗A method includes modulating lightwaves to provide first and second OFDM signal sidebands at a first polarization direction and first and second OFDM signal sidebands at a second polarization direction, and combining sidebands that are oppositely positioned and joined from the first and second OFDM signal sidebands at each polarization direction to provide a polarization multiplexing OFDM signal.
1. An apparatus for generating a 100 Gbit/s orthogonal frequency division multiplexed (OFDM) signal, the apparatus comprising:
a laser that generates an unmodulated optical signal,
four data sources that generate base-band data streams one through four,
four electrical mixers that mix the four base-band data streams at a frequency, f, to generate four up-converted data streams,
at least one optical splitter that splits the unmodulated optical signal into four optical signals,
a first through fourth optical intensity modulator, each intensity modulator configured to modulate one of the four optical signals with one of the up-converted data streams, thereby generating a carrier suppressed optical signal with at least two sidebands,
a first optical interleaver configured to combine an upper sideband from the first intensity modulator with a lower sideband from the second intensity modulator to generate a first frequency division multiplexed (FDM) optical signal,
a second optical interleaver configured to combine an upper sideband from the third optical modulator with a lower sideband from the fourth intensity modulator to generate a second FDM optical signal, and
a polarization beam combiner (PBC) that combines one polarization of the first FDM optical signal with an orthogonal polarization of the second FDM optical signal, thereby generating a 100 Gbit/s OFDM signal.
2. The apparatus of claim 1 , wherein the OFDM signal has a bit rate of at least 100 Gbit/s.
3. The apparatus of claim 1 , wherein the sidebands comprise oppositely positioned single sidebands about an RF frequency f.
4. The apparatus of claim 1 , wherein the sidebands comprise a first oppositely positioned sideband pair centered about an RF frequency f 1 and a second oppositely positioned sideband pair centered about an RF frequency f 2 , frequency f 1 .
5. A method for generating a 100 Gbit/s orthogonal frequency division multiplexed (OFDM) signal, the method comprising the steps of:
generating, responsive to a laser, an unmodulated optical signal,
generating, responsive to four data sources, base-band data streams one through four,
mixing, responsive to four electrical mixers, the four base-band data streams at a frequency, f, to generate four up-converted data streams,
splitting, responsive to at least one optical splitter, the unmodulated optical signal into four optical signals,
modulating, responsive to a first through fourth optical intensity modulator, one of the four optical signals with one of the up-converted data streams, thereby generating a carrier suppressed optical signal with at least two sidebands,
combining, responsive to a first optical interleaver, an upper sideband from the first intensity modulator with a lower sideband from the second intensity modulator to generate a first frequency division multiplexed (FDM) optical signal,
combining, responsive to a second optical interleaver, an upper sideband from the third optical modulator with a lower sideband from the fourth intensity modulator to generate a second FDM optical signal, and
combining, responsive to a polarization beam combiner (PBC), one polarization of the first FDM optical signal with an orthogonal polarization of the second FDM optical signal, thereby generating a 100 Gbit/s OFDM signal.
6. The method of claim 5 , wherein the OFDM signal has a bit rate of at least 100 Gbit/s.
7. The method of claim 5 , wherein the sidebands comprise oppositely positioned single sidebands about an RF frequency.
8. The method of claim 5 , wherein the sidebands comprise a first oppositely positioned sideband pair centered about an RF frequency f 1 and a second oppositely positioned sideband pair centered about an RF frequency f 2 .
9. The method of claim 5 , wherein the sidebands are oppositely positioned and joined by filtering together for each polarization direction a sideband from the first sidebands with an oppositely positioned sideband from the second sidebands.