Method and apparatus for predistortion

Claim 2

A predistortion apparatus for a nonlinear optical transmission system including a laser and an optional link having a main signal path and a distortion signal path which are applied to the laser to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: a coupler dividing an RF input signal into the main path and the distortion path; a distortion generator located in the distortion path, operative to provide a distortion signal from said RF input signal; a first adjustment network coupled to said distortion generator operative to correct the amplitude of the distortion signal by modulating the laser with the RF input signal over the optical link; and a second adjustment network coupled to said distortion generator in parallel with the first adjustment network to adjust the phase of the distortion signal to substantially match phase distortion generated by modulating the laser with the RF input.

Claim 3

A predistortion apparatus as set forth in claim 1 wherein said second adjustment network includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 4

A predistortion apparatus as set forth in claim 2 wherein said second adjustment network includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 5

A predistortion apparatus as set forth in claim 3 wherein said first adjustment network includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.

Claim 6

A predistortion apparatus as set forth in claim 1 wherein said first adjustment network includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 7

A predistortion apparatus for a nonlinear optical transmission system including a laser diode and an optical link having a main signal path and a distortion signal path which are applied to the laser diode to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: means for dividing an RF input signal into the main path and the distortion path; means, located in the distortion path, for generating a distortion signal from said RF input signal; first means coupled to said distortion signal generating means for correcting the distortion signal to substantially match the distortion generated by modulating the laser diode with the RF input signal; and second means coupled to said distortion signal generating means in parallel with said first means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal over the optical link.

Claim 8

A predistortion apparatus for a nonlinear optical transmission system including a laser diode and an optical link having a main signal path and a distortion signal path which are applied to the laser diode to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: means for dividing an RF input signal into the main path and the distortion path; means, located in the distortion path, for generating a distortion signal from said RF input signal; first means coupled to said distortion signal generating means for correcting the distortion signal to substantially match the distortion generated by modulating the laser diode with the RF input signal; and second means coupled to said distortion signal generating means in parallel with said first means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal over the optical link.

Claim 9

A predistortion apparatus as set forth in claim 6 wherein said first correcting means includes: means for adjusting the amplitude of the distortion signal.

Claim 10

A predistortion apparatus as set forth in claim 7 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 11

A predistortion apparatus as set forth in claim 8 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.

Claim 12

A predistortion apparatus as set forth in claim 6 wherein said second correcting means includes: means for adjusting the phase of the distortion signal.

Claim 13

A predistortion apparatus as set forth in claim 10 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 14

A predistortion apparatus as set forth in claim 11 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 15

A predistortion apparatus as set forth in claim 6 wherein said first correcting means includes: means for adjusting the phase of the distortion signal.

Claim 16

A predistortion apparatus as set forth in claim 13 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 17

A predistortion apparatus as set forth in claim 14 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 18

A predistortion apparatus as set forth in claim 6 wherein said second correcting means includes: means for adjusting the amplitude of the distortion signal.

Claim 19

A predistortion apparatus as set forth in claim 16 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 20

A predistortion apparatus as set forth in claim 17 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.

Claim 21

A predistortion apparatus for a nonlinear optical transmission system including a laser diode and an optical link with an optical amplifier, the system having a main signal path and a distortion signal path which are applied to the laser diode to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: means for dividing an RF input signal into the main path and the distortion path; means, located in the distortion path, for generating a distortion signal from said RF input signal; first means coupled to said distortion signal generating means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal through the optical amplifier; and second means coupled to said distortion signal generating means in parallel with said first means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal over the optical link.

Claim 22

A predistortion apparatus for a nonlinear optical transmission system including a laser diode and an optical link with an optical amplifier, the system having a main signal path and a distortion signal path which are applied to the laser diode to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: means for dividing an RF input signal into the main path and the distortion path; means, located in the distortion path, for generating a distortion signal from said RF input signal; first means coupled to said distortion signal generating means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal through the optical amplifier; and second means coupled to said distortion signal generating means in parallel with said first means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal over the optical link.

Claim 23

A predistortion apparatus as set forth in claim 19 wherein said first correcting means includes: means for adjusting the amplitude of the distortion signal.

Claim 24

A predistortion apparatus as set forth in claim 20 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 25

A predistortion apparatus as set forth in claim 21 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.

Claim 26

A predistortion apparatus as set forth in claim 19 wherein said second correcting means includes: means for adjusting the phase of the distortion signal.

Claim 27

A predistortion apparatus as set forth in claim 23 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 28

A predistortion apparatus as set forth in claim 24 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 29

A predistortion apparatus as set forth in claim 19 wherein said first correcting means includes: means for adjusting the phase of the distortion signal.

Claim 30

A predistortion apparatus as set forth in claim 26 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 31

A predistortion apparatus as set forth in claim 27 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 32

A predistortion apparatus as set forth in claim 19 herein said second correcting means includes: means for adjusting the amplitude of the distortion signal.

Claim 33

A predistortion apparatus as set forth in claim 29 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 34

A predistortion apparatus as set forth in claim 30 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.

Claim 35

A predistortion apparatus for a nonlinear optical transmission system including a laser diode and an optical link with an optical amplifier, the system having a main signal path and a distortion signal path which are applied to the laser diode to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: means for dividing an RF input signal into the main path and the distortion path; means, located in the distortion path, for generating a distortion signal from said RF input signal; first means coupled to said distortion signal generating means for correcting the distortion signal to substantially match the distortion generated by modulating the laser diode with the RF input signal; and second means coupled to said distortion signal generating means in parallel with said first means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal through the optical amplifier.

Claim 36

A predistortion apparatus for a nonlinear optical transmission system including a laser diode and an optical link with an optical amplifier, the system having a main signal path and a distortion signal path which are applied to the laser diode to modulate the optical intensity of its output and provide a modulated optical signal, said circuit comprising: means for dividing an RF input signal into the main path and the distortion path; means, located in the distortion path, for generating a distortion signal from said RF input signal; first means coupled to said distortion signal generating means for correcting the distortion signal to substantially match the distortion generated by modulating the laser diode with the RF input signal; and second means coupled to said distortion signal generating means in parallel with said first means for correcting the distortion signal to substantially match the distortion generated by transmitting the modulated optical signal through the optical amplifier.

Claim 37

A predistortion apparatus as set forth in claim 32 wherein said first correcting means includes: means for adjusting the amplitude of the distortion signal.

Claim 38

A predistortion apparatus as set forth in claim 33 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 39

A predistortion apparatus as set forth in claim 34 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.

Claim 40

A predistortion apparatus as set forth in claim 32 wherein said second correcting means includes: means for adjusting the phase of the distortion signal.

Claim 41

A predistortion apparatus as set forth in claim 36 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 42

A predistortion apparatus as set forth in claim 37 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 43

A predistortion apparatus as set forth in claim 32 wherein said first correcting means includes: means for adjusting the phase of the distortion signal.

Claim 44

A predistortion apparatus as set forth in claim 39 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal as a function of frequency.

Claim 45

A predistortion apparatus as set forth in claim 40 wherein said phase adjusting means includes: means for adjusting the phase of the distortion signal without substantially adjusting the amplitude of the distortion signal.

Claim 46

A predistortion apparatus as set forth in claim 32 wherein said second correcting means includes: means for adjusting the amplitude of the distortion signal.

Claim 47

A predistortion apparatus as set forth in claim 42 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal as a function of frequency.

Claim 48

A predistortion apparatus as set forth in claim 43 wherein said amplitude adjusting means includes: means for adjusting the amplitude of the distortion signal without substantially adjusting the phase of the distortion signal.