Optical module

1. An optical module, comprising:

a photoelectric converter;

a first demodulation circuit; and

a second demodulation circuit at least partially separate from the first demodulation circuit,

wherein:

the first demodulation circuit and the second demodulation circuit are electrically connected to the photoelectric converter;

the photoelectric converter is configured to convert a received optical signal into an electrical signal; and

the first demodulation circuit is configured to demodulate the electrical signal to generate a first electrical signal at a first frequency, and the second demodulation circuit is configured to demodulate the electrical signal to generate a second electrical signal at a second frequency higher than the second frequency.

2. The optical module of claim 1 , wherein the first electric signal carries high speed communication service data and the second electric signal carries low speed communication control information.

3. The optical module of claim 2 , wherein the second electric signal carries the low speed communication control information for performing an Auxiliary Management and Control Channel (AMCC) function.

4. The optical module of claim 2 , wherein the first electric signal carries the high speed communication service data at higher than 1 gigabits per second and the second electric signal carries the low speed communication control information at a lower than 1 megabits per second.

5. The optical module of claim 2 , wherein the first electric signal carries the high speed communication service data in a digital form and the second electric signal carries the low speed communication control information in an analog form.

6. The optical module of claim 3 , wherein the first electric signal carries the high speed communication service data and the second electric signal carries the low speed communication control information in a digital form.

7. The optical module of claim 1 , wherein the first frequency is higher than 1 GHz and the second frequency is lower than 1 MHz.

8. The optical module of claim 1 , wherein:

the electric signal converted by the photoelectric converter comprises a current signal;

the first demodulation circuit comprises a transimpedance amplifier circuit; and

the transimpedance amplifier circuit is electrically connected to the photoelectric converter, and is configured to convert the current signal from the photoelectric converter into a voltage signal.

9. The optical module of claim 8 , wherein the transimpedance amplifier circuit comprises a multi-stage current-to-voltage amplifying unit.

10. The optical module of claim 9 , wherein the multi-stage current-to-voltage amplifying unit comprises at least one differential amplifier.

11. The optical module of claim 8 , wherein the first demodulation circuit further comprises a limiting amplifier electrically connected to the transimpedance amplifier circuit, and configured to convert the voltage signal from the transimpedance amplifier circuit to a limiting amplified voltage signal.

12. The optical module of claim 11 , wherein the limiting amplifier comprises a plurality of cascading amplifiers.

13. The optical module of claim 12 , wherein the limiting amplifier further comprises an offset correction circuit.

14. The optical module of claim 1 , wherein:

the electric signal converted by the photoelectric converter comprises a current signal;

the first demodulation circuit comprises a transimpedance amplifier electrically connected to the photoelectric converter for converting the current signal into a voltage signal; and

a high-pass filter connected to the transimpedance amplifier and configured to perform high-pass filtering of the voltage signal to filter out signal at the second frequency.

15. The optical module of claim 1 , wherein:

the electric signal converted by the photoelectric converter comprises a current signal;

the second demodulation circuit comprises a current-to-voltage conversion circuit and electrically connected to the photoelectric converter for converting the current signal into a voltage signal.

16. The optical module of claim 15 , wherein the second demodulation circuit further comprises an alternative-current (A.C.) coupling circuit configured to block a direct-current (D.C.) component in the voltage signal and allow an A.C. component to pass through.

17. The optical module of claim 15 , wherein the second demodulation circuit further comprises a low-pass amplifier electrically connected to the current-to-voltage conversion circuit and configured to filter out signal at the first frequency and produce an amplified electrical voltage signal.

18. The optical module of claim 17 , wherein the second demodulation circuit further comprises:

a low-pass filter electrically connected to the low-pass amplifier and configured to filter out A.C. components of the amplified electrical voltage signal and allow a D.C. component to pass through; and

a comparator electrically connected to the low-pass amplifier and the low-pass filter, and configured to compare the amplified electrical voltage signal and the D.C. component to generate a quasi-binary electrical signal.

19. The optical module of claim 1 , wherein the second demodulation circuit comprises:

the electric signal converted by the photoelectric converter comprises a current signal;

a current mirroring circuit electrically connected to the photoelectric converter and configured to receive the current signal and perform low-pass filtering to remove signal at the first frequency to output a mirror current signal; and

a sample-and-hold circuit electrically connected to the current mirroring circuit for converting the mirror current signal into a voltage signal.

20. The optical module of claim 19 , wherein the second demodulation circuit further comprises an operational amplifier electrically connected to the sample-and-hold circuit.