Optical module
The present disclosure provides an optical module comprising: a photoelectric conversion unit, a first demodulation circuit, and a second demodulation circuit; the first demodulation circuit and the second demodulation circuit are respectively connected to the photoelectric conversion unit; the photoelectric conversion unit is configured to convert the received optical signal into an electrical signal; the first demodulation circuit is configured to demodulate an electrical signal converted by the photoelectric conversion unit and generate a high-frequency electrical signal; the second demodulation circuit is configured to demodulate an electrical signal converted by the photoelectric conversion unit and generate a low-frequency electrical signal.
1. An optical module, comprising: a photoelectric conversion unit, a first demodulation circuit, and a second demodulation circuit separate from the first demodulation circuit; wherein
the first demodulation circuit and the second demodulation circuit are respectively connected to the photoelectric conversion unit;
the photoelectric conversion unit is configured to convert a received optical signal into an electrical signal, wherein the electrical signal comprises a high-frequency electrical signal and a low-frequency electrical signal;
the first demodulation circuit is configured to demodulate the electrical signal converted by the photoelectric conversion unit and generate a high-frequency electrical signal; and
the second demodulation circuit is configured to demodulate the electrical signal converted by the photoelectric conversion unit and generate a low-frequency electrical signal.
2. The optical module according to claim 1 , wherein the first demodulation circuit comprises a transimpedance amplifier circuit and wherein:
the transimpedance amplifier circuit is electrically connected to the photoelectric conversion unit, and is configured to convert a current signal output from the photoelectric conversion unit into a voltage signal comprising the high-frequency electrical signal.
3. The optical module according to claim 2 , wherein the transimpedance amplifier circuit comprises:
a current-to-voltage conversion amplifier electrically connected to the photoelectric conversion unit, wherein the current-to-voltage conversion amplifier is configured to convert the current signal output from the photoelectric conversion unit into an intermediate voltage signal.
4. The optical module according to claim 3 , wherein the transimpedance amplifier circuit further comprises:
a differential amplifier electrically connected to the current-to-voltage conversion amplifier, wherein the differential amplifier is configured to convert the intermediate voltage signal from the current-to-voltage conversion amplifier to a differential voltage output comprising the high-frequency electrical signal.
5. The optical module according to claim 2 , wherein the first demodulation circuit further comprises a limiting amplifier and wherein
the limiting amplifier is electrically connected to the transimpedance amplifier circuit, and is configured to convert the voltage signal from the transimpedance amplifier circuit to a limiting amplified voltage signal comprising the high-frequency electrical signal.
6. The optical module according to claim 5 , wherein the limiting amplifier comprises one or more cascading amplifiers to amplify the voltage signal from the transimpedance amplifier circuit to obtain the limiting amplifier voltage signal.
7. The optical module according to claim 6 , wherein the limiting amplifier further comprises power detector for connected to an intermediate output of the one or more cascading amplifiers.
8. The optical module according to claim 6 , wherein the limiting amplifier further comprises an offset correction circuit.
9. The optical module according to claim 1 , wherein the second demodulation circuit comprises a current-to-voltage conversion circuit and wherein:
the current-to-voltage conversion circuit electrically connects to the photoelectric conversion unit; and
the current-to-voltage conversion circuit is configured to convert a signal output from the photoelectric conversion unit into a voltage signal.
10. The optical module according to claim 9 , wherein the voltage signal comprises the high-frequency electrical signal and the low-frequency electrical signal.
11. The optical module according to claim 9 , 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.
12. The optical module according to claim 9 , wherein:
the second demodulation circuit further comprises a low-pass amplifier, wherein the low-pass amplifier electrically connects to the current-to-voltage conversion circuit, and is configured to filter out high-frequency signal and amplify a low-frequency signal to produce an amplified low-frequency electrical voltage signal.
13. The optical module according to claim 12 , wherein the amplified low-frequency electrical voltage signal comprises a direct-current (D.C.) component and the low-frequency electrical signal.
14. The optical module according to claim 12 , wherein:
the second demodulation circuit further comprises a low-pass filter comprising an input terminal and an output terminal, wherein the input terminal of the low-pass filter electrically connects to the low-pass amplifier and the low-pass filter is configured to filter out an A.C. component and allow a D.C. component passing through; and
the second demodulation circuit comprises a comparator comprising a first input terminal and a second input terminal, wherein:
the first input terminal of the comparator electrically connects to the low-pass amplifier and is configured to receive the amplified low-frequency electrical voltage signal,
the second input terminal of the comparator electrically connects to the output terminal of the low-pass filter, and
the comparator is configured to output a quasi-binary electrical signal.
15. The optical module according to claim 14 , wherein:
the amplified low-frequency electrical voltage signal comprises a direct current (D.C.) component and the low-frequency electrical signal;
electric signal at the output terminal of the low-pass filter comprises the D.C. component of the amplified low-frequency electrical voltage signal; and
the quasi-binary electrical signal comprises the low-frequency electrical signal.
16. The optical module according to claim 9 , wherein the current-to-voltage conversion circuit comprises a resistor.
17. The optical module according to claim 1 , wherein:
the second demodulation circuit comprises a first low-pass filter with a first cut-off frequency, a second low-pass filter with a second cut-off frequency, and a comparator, wherein:
an input terminal of the first low-pass filter electrically connects to the photoelectric conversion unit and is configured to receive the electrical signal from the photoelectric conversion unit and output a first signal;
an input terminal of the second low-pass filter electrically connects to the photoelectric conversion unit and is configured to receive the electrical signal from the photoelectric conversion unit and output a second signal; and
the comparator is configured to compare the first signal and the second signal.
18. The optical module according to claim 17 , wherein the first cut-off frequency is smaller than the second cut-off frequency.
19. The optical module according to claim 17 , wherein:
the first signal comprises a direct current (D.C.) component of the electrical signal;
the second signal comprises a low-frequency component of the electrical signal; and
output signal from the comparator comprises quasi-binary signal.
20. The optical module according to claim 1 , wherein:
a frequency of the high-frequency electrical signal is between 1 GHz and 10 GHz; and
a frequency of the low-frequency electrical signal is between 50 KHz and 1 MHz.
21. The optical module according to claim 1 , wherein the high-frequency electric signal from the first demodulation circuit comprises a differential electric signal wherein as the low-frequency electric signal from the second demodulation circuit comprises a non-differential electric signal.