Optical transceiver and optical coherent receiving system

A coherent optical communications system, comprising a first optical transceiver and a second optical transceiver, wherein:

• the first optical transceiver comprises a first laser, a first electro-optic modulator, and a first optical receiver, the second optical transceiver comprises a second laser, a second electro-optic modulator, and a second optical receiver, the first optical receiver comprises a first mixer, a first optical-to-electrical converter, a first analog-to-digital converter, and a first digital signal processor, and the second optical receiver comprises a second mixer, a second optical-to-electrical converter, a second analog-to-digital converter, and a second digital signal processor;
• the first laser is configured to:
• transmit a part of emitted laser light to the second mixer as first local oscillator light by using a first polarization-maintaining optical waveguide;
• and
• transmit another part of the emitted laser light to the first electro-optic modulator, wherein a polarization state of the first local oscillator light remains unchanged when being transmitted in the first polarization-maintaining optical waveguide;
• the first electro-optic modulator is configured to:
• load first data onto laser light received from the first laser to obtain a first optical signal;
• and
• transmit the first optical signal to the second mixer by using a first single-mode optical waveguide;
• the second mixer is configured to mix the first local oscillator light with the first optical signal to obtain a mixed optical signal;
• the second optical-to-electrical converter is configured to convert the mixed optical signal mixed by the second mixer into a first analog electrical signal;
• the second analog-to-digital converter is configured to perform analog-to-digital conversion on the first analog electrical signal to obtain a first digital electrical signal;
• and
• the second digital signal processor is configured to process the first digital electrical signal to obtain the first data;
• the second laser is configured to:
• transmit a part of emitted laser light to the first mixer in the first optical transceiver as second local oscillator light by using a second polarization-maintaining optical waveguide;
• and
• transmit another part of the emitted laser light to the second electro-optic modulator;
• the second electro-optic modulator is configured to:
• load second data onto the laser light received from the second laser to obtain a second optical signal;
• and
• transmit the second optical signal to the first mixer in the first optical transceiver by using a second single-mode optical waveguide;
• the first mixer is configured to mix the second local oscillator light with the second optical signal to obtain a mixed optical signal;
• the first optical-to-electrical converter is configured to convert the mixed optical signal mixed by the first mixer into a second analog electrical signal;
• the first analog-to-digital converter is configured to perform analog-to-digital conversion on the second analog electrical signal to obtain a second digital electrical signal;
• and
• the first digital signal processor is configured to process the second digital electrical signal to obtain the second data.