Patent ID: 11923909
Assignee: BEIJING ZHONGKE GUOGUANG QUANTUM TECHNOLOGY CO., LTD.
Field: Telecommunications (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 4:
5. The self-coherent receiver based on polarization-independent delay interferometers according to claim 1, wherein the first polarization-independent delay interferometer comprises a first polarization beam splitter, a first 45° polarization-rotation structure, a second 45° polarization-rotation structure, a ninth polarization beam splitter, a fifth long-arm optical fiber, and a first 90° polarization-rotation structure;
the first polarization beam splitter is configured to split the first signal light component to generate a first polarized signal light component and a second polarized signal light component;
the first 45° polarization-rotation structure and the second 45° polarization-rotation structure are respectively configured to rotate a polarization state of each of the first polarized signal light component and the second polarized signal light component by 45° correspondingly;
the ninth polarization beam splitter is configured to transmit a horizontal polarization component of the first polarized signal light component to the fifth long-arm optical fiber and reflect a vertical polarization component of the first polarized signal light component, wherein after passing through the fifth long-arm optical fiber, the horizontal polarization component of the first polarized signal light component is polarization-rotated by the first 90° polarization-rotation structure by 90°, and the polarization-rotated horizontal polarization component of the first polarized signal light component and the reflected vertical polarization component of the first polarized signal light component are polarization-combined to generate a first polarization interference optical signal; and the ninth polarization beam splitter is further configured to reflect a horizontal polarization component of the second polarized signal light component and transmit a vertical polarization component of the second polarized signal light component to the fifth long-arm optical fiber, wherein, after passing through the fifth long-arm optical fiber, the vertical polarization component of the second polarized signal light component is polarization-rotated by the first 90° polarization-rotation structure by 90°, and the reflected horizontal polarization component of the second polarized signal light component and the polarization-rotated vertical polarization component of the second polarized signal light component are polarization-combined to generate a second polarization interference optical signal;
the first 45° polarization-rotation structure and the second 45° polarization-rotation structure are further respectively configured to rotate a polarization state of each of the second polarization interference optical signal and the first polarization interference optical signal by 45° correspondingly;
the first polarization beam splitter is further configured to combine the horizontal polarization component of the first polarization interference optical signal and the horizontal polarization component of the second polarization interference optical signal to generate the first interference optical signal; and the first polarization beam splitter is further configured to combine the vertical polarization component of the first polarization interference optical signal and the vertical polarization component of the second polarization interference optical signal to generate the second interference optical signal;
the second polarization-independent delay interferometer comprises a third polarization beam splitter, a third 45° polarization-rotation structure, a fourth 45° polarization-rotation structure, a tenth polarization beam splitter, a sixth long-arm optical fiber, a second 90° polarization-rotation structure and a third phase shifter;
the third polarization beam splitter is configured to split the second signal light component to generate a third polarized signal light component and a fourth polarized signal light component;
the third 45° polarization-rotation structure and the fourth 45° polarization-rotation structure are respectively configured to rotate a polarization state of each of the third polarized signal light component and the fourth polarized signal light component by 45° correspondingly;
the tenth polarization beam splitter is configured to transmit a horizontal polarization component of the third polarized signal light component to the sixth long-arm optical fiber and reflect a vertical polarization component of the third polarized signal light component, wherein, after passing through the sixth long-arm optical fiber, the horizontal polarization component of the third polarized signal light component is polarization-rotated by the second 90° polarization-rotation structure by 90°, and the polarization-rotated horizontal polarization component of the third polarized signal light component and the reflected vertical polarization component of the third polarized signal light component are polarization combined to generate a third polarization interference optical signal; and the tenth polarization beam splitter is further configured to reflect a horizontal polarization component of the fourth polarized signal light component, and transmit a vertical polarization component of the fourth polarized signal light component to the sixth long-arm optical fiber, wherein after passing through the sixth long-arm optical fiber, the vertical polarization component of the fourth polarized signal light component is polarization-rotated by the second 90° polarization-rotation structure by 90°, and the reflected horizontal polarization component of the fourth polarized signal light component and the polarization-rotated vertical polarization component of the fourth polarized signal light component are polarization combined to generate a fourth polarization interference optical signal;
the third phase shifter is configured to adjust a phase of an optical signal passing the sixth long-arm optical fiber, so that a phase difference between the optical signal passing the sixth long-arm optical fiber and an optical signal reflected by the tenth polarization beam splitter is π/2;
the third 45° polarization-rotation structure and the fourth 45° polarization-rotation structure are further respectively configured to rotate a polarization state of each of the fourth polarization interference optical signal and the third polarization interference optical signal by 45° correspondingly;
the third polarization beam splitter is further configured to combine a horizontal polarization component of the third polarization interference optical signal and a horizontal polarization component of the fourth polarization interference optical signal to generate the third interference optical signal; and the third polarization beam splitter is further configured to combine a vertical polarization component of the third polarization interference optical signal and a vertical polarization component of the fourth polarization interference optical signal to generate the fourth interference optical signal.