Off quadrature biasing of mach zehnder modulator for improved OSNR performance
View Patent ↗An integrated optical modulator device. The device can include a driver module coupled to an optical modulator. The optical modulator is characterized by a raised cosine transfer function. This optical modulator can be coupled to a light source and a bias control module, which is configured to apply an off-quadrature bias to the optical modulator. This bias can be accomplished by applying an inverse of the modulator transfer function to the optical modulator in order to minimize a noise variance. This compression function can result in an optimized increased top eye opening for a signal associated with the optical modulator. Furthermore, the optical modulator can be coupled to an EDFA (Erbium Doped Fiber Amplifier) that is coupled to a filter coupled an O/E (Optical-to-Electrical) receiver.
1. A hybrid communication module comprising:
a silicon substrate having a first region and a second region;
a communication bus configured between the first region and the second region;
a silicon photonic device overlaying the first region of the substrate, the silicon photonic device comprising an optical modulator and a light source, the optical modulator being characterized by a raised sine transfer function, the optical modulator including an input coupled to a bias control signal; and
an electrical silicon device overlaying the second region of the substrate, the electrical silicon device comprising a bias control circuit coupled to the optical modulator via the communication bus, the bias control circuit being configured to generate the bias signal for minimizing a noise variance that is proportional to 2√{square root over (nΔP ASE )}, wherein nΔ is a signal level n and P ASE is an Amplified Spontaneous Emission Power.
2. The module of claim 1 wherein bias control circuit is configured to apply a compression function to the optical modulator to apply an off-quadrature bias.
3. The module of claim 1 wherein the silicon photonic device further comprises an Erbium Dope Fiber Amplifier.
4. The module of claim 1 wherein the electrical silicon device further comprises an electrical interface.
5. The module of claim 1 wherein the silicon photonic device further comprises an optical interface.
6. The module of claim 1 the bias control circuit is configured to apply a compression function to cause a signal associated with the optical modulator to exhibit an expanded top eye opening region and a compressed bottom eye opening region.
7. The module of claim 1 wherein the silicon photonic device further comprises an optical-to electrical receiver.
8. The module of claim 1 wherein the electrical silicon device further comprises a driver circuit coupled to the optical modulator via the communication bus.
9. The module of claim 8 wherein the driver circuit comprises a different input, single-ended output, variable gain, linear driver.
10. The module of claim 1 wherein the silicon photonic device further comprises a first variable optical attenuator.
11. The module of claim 10 wherein the silicon photonic device further comprises a second variable optical attenuator.
12. The module of claim 11 wherein the photonic device further comprises a tunable optical filter coupled to the second variable optical attenuator.
13. The module of claim 1 wherein the optical modulator comprises a Mach Zehnder Modulator.
14. A multi-chip communication module, the module comprising:
a printed circuit board (PCB) having a first region and a second region;
a communication bus positioned between the first region and the second region;
a silicon photonic device overlaying the first region of the PCB, the silicon photonic device comprising a Mach Zehnder Modulator (MZM) and a light source, the MZM being configured to a pulse amplitude modulation (PAM) signal, the MZM including an input coupled to a bias control signal; and
an electrical silicon device overlaying the second region of the PCB, the electrical silicon device comprising a bias control circuit coupled to the MZM via the communication bus, the bias control circuit being configured to generate the bias signal for minimizing a noise variance that is proportional to 2√{square root over (nΔP ASE )}, wherein nΔ is a signal level n and P ASE is an Amplified Spontaneous Emission Power.
15. The module of claim 14 wherein the communication bus comprises a plurality of PBC traces.
16. The module of claim 14 wherein the PAM signal is characterized by a top eye opening region and a bottom eye opening region.
17. The module of claim 14 wherein the MZM is characterized by a raised cosine transfer function.
18. The module of claim 14 wherein the bias control circuit is configured to apply a DC compression function to the MZM.
19. The module of claim 18 wherein the DC compression function comprises an inverse raised sine function.
20. A hybrid communication module comprising:
a silicon substrate having a first region and a second region;
a silicon photonic device overlaying the first region of the substrate, the silicon photonic device comprising an optical modulator, the optical modulator being characterized by a raised sine transfer function, the optical modulator including an input coupled to a bias control signal; and
an electrical silicon device overlaying the second region of the substrate, the electrical silicon device comprising a bias control circuit coupled to the optical modulator, the bias control circuit being configured apply a DC compression function to the optical modulator to bias the optical modulator off-quadrature for minimizing a noise variance that is proportional to 2√{square root over (nΔP ASE )}, wherein nΔ is a signal level n and P ASE is an Amplified Spontaneous Emission Power.