Ultra-wide range optical wavelength converter by direct signal translation from integrated coherent receiver to dual-polarization IQ modulator
A method of wavelength conversion without polarization tracking is provided. A system is also provided that converts an input signal into an output signal of a different wavelength that contains all of the amplitude, phase, and polarization information of the original signal. The method includes separating, using a polarization-diversity optical mixer, an input optical signal of a first wavelength into a plurality of electrical signals containing amplitudes and phases while maintaining the polarization information of the input signal, converting each of the amplitudes and phases into individual photo-currents using a photo-diode, converting each of the output photo-currents into voltages using an amplifier, modulating the multitude of voltages to a second wavelength using a modulator, where the separated electrical signals are up-converted to generate an output optical signal that maintains the same amplitude, phase, and polarization information as was contained in the input signal.
1. A wavelength converter, comprising:
a signal down-converter configured to down-convert an optical signal of a first wavelength into a plurality of amplitudes and phases and which includes a polarization-diverse optical mixer configured to separate an incoming input signal into a plurality of split portions of amplitudes and phases while maintaining polarization information, a photo-diode configured to convert each amplitude or phase into a photo-current, and an amplifier configured to convert each photo-current into a voltage,
wherein the down-converter generates down-converted signals (I X ′, Q X ′, I Y ′, Q Y ′) with relation to an original signal (I X , Q X , I Y , Q Y ) with a local oscillator (LO) laser tuned to an incoming signal wavelength λ1 as:
I
X
′
+
iQ
X
′
=
(
(
I
X
+
iQ
X
)
cos
ϕ
+
(
I
Y
+
iQ
Y
)
sin
ϕ
)
ⅇ
ⅈ
(
ω
λ
1
-
ω
LO
)
t
I
Y
′
+
iQ
Y
′
=
(
-
(
I
X
+
iQ
X
)
sin
ϕ
+
(
I
Y
+
iQ
Y
)
cos
ϕ
)
ⅇ
ⅈ
(
ω
λ
1
-
ω
LO
)
t
where ω is frequency, i is the imaginary number, φ is an angle of difference between a signal's orientation of polarization and an integrated coherent receiver (ICR) and polarities of an optical modulator bias are maintained to ensure signal phases are either both fixed or flipped in X or Y polarization to ensure correct wavelength conversion; and
a signal up-converter configured to modulate split portions of amplitudes and phases optical signal of the first wavelength to a second wavelength and then combine the down-converted modulated optical signal into an output optical signal of a second wavelength while maintaining the polarization information of the original signal and which includes a modulator that is configured to modulate the amplitudes and phases to the second wavelength.
2. The wavelength converter as described in claim 1 , wherein a first light emitting device is included which sends light into the signal down-converter at the same wavelength as an original optical signal.
3. The wavelength converter as described in claim 2 , wherein the first light emitting device is split off from an optical source of a transponder sitting at a local node.
4. The wavelength converter as described in claim 2 , wherein the first light emitting device is a local oscillator laser.
5. The wavelength converter as described in claim 1 , wherein the photo-diode is a balanced photo-diode.
6. The wavelength converter as described in claim 1 , wherein the amplifier is a trans-impedance amplifiers.
7. The wavelength converter as described in claim 1 , wherein the modulator is a dual-polarized dual-nested Mach-Zehnder modulator.
8. The wavelength converter as described in claim 1 , further comprising a signal combiner includes a second light emitting device that sends light into modulators at the same wavelength as the output optical signal.
9. The wavelength converter as described in claim 8 , wherein the second light emitting device is a laser.
10. A method of wavelength conversion, comprising:
separating, using a polarization-diversity optical mixer, an input optical signal of a first wavelength into a plurality of amplitudes and phases while maintaining the polarization information of the input signal;
generating down-converted signals (I X ′, Q X ′, I Y ′, Q Y ′) with relation to an original signal (I X , Q X , I Y , Q Y ) with a local oscillator LO laser tuned to an incoming signal wavelength λ1 as:
I
X
′
+
iQ
X
′
=
(
(
I
X
+
iQ
X
)
cos
ϕ
+
(
I
Y
+
iQ
Y
)
sin
ϕ
)
ⅇ
ⅈ
(
ω
λ
1
-
ω
LO
)
t
I
Y
′
+
iQ
Y
′
=
(
-
(
I
X
+
iQ
X
)
sin
ϕ
+
(
I
Y
+
iQ
Y
)
cos
ϕ
)
ⅇ
ⅈ
(
ω
λ
1
-
ω
LO
)
t
where ω is frequency, i is the imaginary number, φ is an angle of difference between a signal's orientation of polarization and an integrated coherent receiver (ICR) and polarities of an optical modulator bias are maintained to ensure signal phases are either both fixed or flipped in X or Y polarization to ensure correct wavelength conversion; and
converting each of the amplitudes and phases into individual photo-currents using a photo-diode;
converting output photo-currents into voltages using an amplifier;
modulating voltages to a second wavelength using a modulator; and
recombining a plurality of amplitudes and phases to generate an output optical signal that maintains a polarization information of the input signal.
11. The method according to claim 10 , wherein a first light emitting device sends light into the polarization-diversity optical mixer at the same wavelength that an original optical signal is sent.
12. The method according to claim 11 , wherein the light emitting device down-converts the contents of the input signal to a baseband electrical signal.
13. The method according to claim 10 , wherein the photo-diode is a balanced photo-diode.
14. The method according to claim 10 , wherein the amplifier is a trans-impedance amplifier.
15. The method according to claim 10 , wherein the modulator is a dual-polarized dual-nested Mach-Zehnder modulator.
16. The method according to claim 10 , wherein a second light emitting device sends light at a wavelength of the output optical signal into a plurality of modulators.
17. The method according to claim 10 , wherein the second light emitting device is a laser.