Patent ID: 11949461
Assignee: BEIJING ZHONGKE GUOGUANG QUANTUM TECHNOLOGY CO., LTD.
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 6:
7. The integrated self-coherent receiving optical chip based on round-trip delay interferometers according to claim 1, wherein the non-reciprocal polarization rotation modules comprise a second notch groove, a third half-wave plate, a fourth half-wave plate and a first Faraday rotation plate, and
wherein the second notch groove is configured to transversely run through the first optical waveguide, the second optical waveguide, the third optical waveguide, and the fourth optical waveguide;
the third half-wave plate is aligned with one end of the first Faraday rotation plate and attached to the first Faraday rotation plate at a first side of the first Faraday rotation plate; and the fourth half-wave plate is aligned with a second end of the first Faraday rotation plate and attached to the first Faraday rotation plate at the first side of the first Faraday rotation plate, and is placed in the second notch groove;
the first Faraday rotation plate is configured to transversely run through the first optical waveguide, the second optical waveguide, the third optical waveguide, and the fourth optical waveguide;
the third half-wave plate is configured to transversely run through the first optical waveguide and the second optical waveguide;
the fourth half-wave plate is configured to transversely run through the third optical waveguide and the fourth optical waveguide;
a first reflective film is coated on the first side of the first Faraday rotation plate where the third half-wave plate is attached to, and at a gap between the third half-wave plate and the fourth half-wave plate;
an angle between a main axis of the third half-wave plate and a horizontal direction, and an angle between a main axis of the fourth half-wave plate and the horizontal direction are both 22.5°, and a polarization rotation angle of a first Faraday rotation optical waveguide is 45°;
the first round-trip delay interferometer comprises a second beam splitter, a nineteenth optical waveguide, and a twentieth optical waveguide;
the second round-trip delay interferometer comprises a third beam splitter, a twenty-first optical waveguide, a first phase shifter and a twenty-second optical waveguide,
the nineteenth optical waveguide, the twentieth optical waveguide, the twenty-first optical waveguide and the twenty-second optical waveguide are all connected to a second side of the first Faraday rotation optical waveguide at a part corresponding to the first reflective film;
a length difference between the nineteenth optical waveguide and the twentieth optical waveguide is equal to half of an arm length difference of the first round-trip delay interferometer; a length difference between the twenty-first optical waveguide and the twenty-second optical waveguide is equal to half of an arm length difference of the second round-trip delay interferometer;
the second beam splitter is configured to split the first signal light component to generate a first component and a second component with a same amplitude;
the third beam splitter is configured to split the second signal light component to generate a third component and a fourth component with a same amplitude;
the first reflective film and the first Faraday rotation optical waveguide are together configured to rotate polarization states of the first component, the second component, the third component and the fourth component respectively by 90° and reflect the first component, the second component, the third component and the fourth component;
the first phase shifter is configured to increase the third component by π/2 phase;
the second beam splitter is further configured to interfere the reflected first component and the reflected second component to generate the first interference optical signal and the second interference optical signal; and
the third beam splitter is further configured to interfere the reflected third component and the reflected fourth component to generate the third interference optical signal and the fourth interference optical signal.