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

Claim 2:
3. 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 second polarization beam splitter, a first long-arm optical fiber, a first short-arm optical fiber and a first reflection module;
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 second polarization beam splitter is configured to transmit a horizontal polarization component of the first polarized signal light component to the first long-arm optical fiber and reflect a vertical polarization component of the first polarized signal light component to the first short-arm optical fiber; and to reflect a horizontal polarization component of the second polarized signal light component to the first long-arm optical fiber and transmit a vertical polarization component of the second polarized signal light component to the first short-arm optical fiber;
the first reflection module is configured to respectively reflect the horizontal polarization component of the first polarized signal light component transmitted through the first long-arm optical fiber and the vertical polarization component of the first polarized signal light component transmitted through the first short-arm optical fiber, such that a polarization state of each of the horizontal polarization component of the first polarized signal light component transmitted through the first long-arm optical fiber and the vertical polarization component of the first polarized signal light component transmitted through the first short-arm optical fiber is rotated by 90°; and the first reflection module is configured to respectively reflect the horizontal polarization component of the second polarized signal light component transmitted through the first long-arm optical fiber and the vertical polarization component of the second polarized signal light component transmitted through the first short-arm optical fiber, such that a polarization state of each of the horizontal polarization component of the second polarized signal light component transmitted through the first long-arm optical fiber and the vertical polarization component of the second polarized signal light component transmitted through the first short-arm optical fiber is rotated by 90°;
the second polarization beam splitter is further configured to perform a polarization interference on the reflected horizontal polarization component and the reflected vertical polarization component of the first polarized signal light component to generate a first polarization interference optical signal; and to perform a polarization interference on the reflected horizontal polarization component and the reflected vertical polarization component of the second polarized signal light component, 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 a horizontal polarization component of the first polarization interference optical signal and a horizontal polarization component of the second polarization interference optical signal to generate the first interference optical signal; and to combine a vertical polarization component of the first polarization interference optical signal and a 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 fourth polarization beam splitter, a second long-arm optical fiber, a second short-arm optical fiber, a first phase shifter and a second reflection module;
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 fourth polarization beam splitter is configured to transmit a horizontal polarization component of the third polarized signal light component to the second long-arm optical fiber, and reflect a vertical polarization component of the third polarized signal light component to the second short-arm optical fiber; and the fourth polarization beam splitter is configured to reflect a horizontal polarization component of the fourth polarized signal light component to the second long-arm optical fiber, and transmit a vertical polarization component of the fourth polarized signal light component to the second short-arm optical fiber;
the second reflection module is configured to respectively reflect the horizontal polarization component of the third polarized signal light component transmitted through the second long-arm optical fiber and the vertical polarization component of the third polarized signal light component transmitted through the second short-arm optical fiber, such that a polarization state of each of the horizontal polarization component of the third polarized signal light component transmitted through the second long-arm optical fiber and the vertical polarization component of the third polarized signal light component transmitted through the second short-arm optical fiber is rotated by 90°; and the second reflection module is configured to respectively reflect the horizontal polarization component of the fourth polarized signal light component transmitted through the second long-arm optical fiber and the vertical polarization component of the fourth polarized signal light component transmitted through the second short-arm optical fiber, such that a polarization state of each of the horizontal polarization component of the fourth polarized signal light component transmitted through the second long-arm optical fiber and the vertical polarization component of the fourth polarized signal light component transmitted through the second short-arm optical fiber is rotated by 90°;
the first phase shifter is configured to adjust a phase of an optical signal passing the second short-arm optical fiber, so that a phase difference between the optical signal passing the second short-arm optical fiber and an optical signal passing the second long-arm optical fiber is π/2;
the fourth polarization beam splitter is further configured to perform a polarization interference on the reflected horizontal polarization component and the reflected vertical polarization component of the third polarized signal light component, to generate a third polarization interference optical signal, and the fourth polarization beam splitter is further configured to perform a polarization interference on the reflected horizontal polarization component and the reflected vertical polarization component of the fourth polarized signal light component, to generate a fourth polarization interference optical signal;
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.