Dual-stage optical isolator core and optical isolator

An optical isolator, comprising:

• an input waveguide, a lens, an optical isolator core, and an output waveguide that are successively arranged along the forward direction of the optical path;
• wherein,
• the optical isolator core comprises:
• a first birefringent crystal, a first Faraday rotator, a second birefringent crystal, a second Faraday rotator, and a third birefringent crystal that are successively arranged along the forward optical path;
• the first birefringent crystal, the first Faraday rotator, the second birefringent crystal, the second Faraday rotator and the third birefringent crystal are all parallel plate structures;
• the input waveguide is configured to import divergent beam along the forward direction of the optical path and output it to the lens, the lens is configured to convert the divergent beam into convergent beam and output it to the first birefringent crystal in the optical isolator core;
• wherein in the case that forward light is incident on the first birefringent crystal, the first birefringent crystal is configured to separate the forward light into first crystal forward o light and first crystal forward e light whose polarization directions are perpendicular to each other, and then output them to the first Faraday rotator;
• the first crystal forward o light generates a first displacement of the first crystal forward o light and the first crystal forward e light generates a first displacement of the first crystal forward e light respectively;
• the first Faraday rotator is configured to rotate the polarization direction of the first crystal forward o-light and the first crystal forward e-light by an angle of α1 in the first rotation direction, and then output them to the second birefringent crystal, where α1=45°;
• the second birefringent crystal is configured to cause the first crystal forward o-light to generate a second displacement of the first crystal forward o-light, and the first crystal forward e-light to generate a second displacement of the first crystal forward e-light, and then output them to the second Faraday rotator;
• the second Faraday rotator is configured to rotate the polarization direction of the first crystal forward o-light and the first crystal forward e-light by an angle of α2 in the second rotation direction, and then output them to the third birefringent crystal, where α2=45°;
• the third birefringent crystal is configured to cause the first crystal forward o-light to generate a third displacement of the first crystal forward o-light, and the first crystal forward e-light to generate a third displacement of the first crystal forward e-light;
• wherein a sum of the first displacement of the first crystal forward o light, the second displacement of the first crystal forward o light, and the third displacement of the first crystal forward o light is equal to a sum of the first displacement of the first crystal forward e light, the second displacement of the first crystal forward e light, and the third displacement of the first crystal forward e light, and the first crystal forward o light and the first crystal forward e light are coincident with each other in response to exiting from the third birefringent crystal;
• and the third birefringent crystal in the optical isolator core is configured to output the recombined beam of the first crystal forward o-light and the first crystal forward e-light to the output waveguide, and the output waveguide is configured to export the recombined beam;
• wherein in the case that backward light entering backward along the forward optical path is incident on the third birefringent crystal, the third birefringent crystal is configured to separate the backward light into a third crystal backward o light and a third crystal backward e light whose polarization directions are perpendicular to each other, and then output them to the second Faraday rotator, such that the third crystal backward o light and the third crystal backward e light respectively generate a third displacement of the third crystal backward o light and a third displacement of the third crystal backward e light;
• the second Faraday rotator is configured to rotate the polarization directions of the third crystal backward o light and the third crystal backward e light by an angle of α2 in the second rotation direction, and then output them to the second birefringent crystal;
• the second birefringent crystal is configured to cause the third crystal backward o light to generate a second displacement of the third crystal backward o light, and the third crystal backward e light to generate a second displacement of the third crystal backward e light, and then output them to the first Faraday rotator;
• the first Faraday rotator is configured to rotate the polarization directions of the third crystal backward o light and the third crystal backward e light by an angle of α1 in the first rotation direction, and then output them to the first birefringent crystal;
• the first birefringent crystal is configured to cause the third crystal backward o light to generate a first displacement of the third crystal backward o light, and the third crystal backward e light to generate a first displacement of the third crystal backward e light;
• wherein a sum of the first displacement of the third crystal backward o light, the second displacement of the third crystal backward o light, and the third displacement of the third crystal backward o light causes the third crystal backward o light to deviate from the forward optical path, and a sum of the first displacement of the third crystal backward e light, the second displacement of the third crystal backward e light, and the third displacement of the third crystal backward e light causes the third crystal backward e light to deviate from the forward optical path, to prevent backward light from coupling into the input waveguide after passing through the lens.

An optical isolator, comprising:

• an input waveguide, an optical isolator core, a lens, and an output waveguide that are successively arranged along the forward direction of the optical path;
• the optical isolator core comprises:
• a first birefringent crystal, a first Faraday rotator, a second birefringent crystal, a second Faraday rotator, and a third birefringent crystal that are successively arranged along the forward optical path;
• the first birefringent crystal, the first Faraday rotator, the second birefringent crystal, the second Faraday rotator and the third birefringent crystal are all parallel plate structures;
• the input waveguide is configured to import divergent beam along the forward direction of the optical path and output it to the first birefringent crystal;
• wherein in the case that forward light is incident on the first birefringent crystal, the first birefringent crystal is configured to separate the forward light into first crystal forward o light and first crystal forward e light whose polarization directions are perpendicular to each other, and then output them to the first Faraday rotator;
• the first crystal forward o light generates a first displacement of the first crystal forward o light and the first crystal forward e light generates a first displacement of the first crystal forward e light respectively;
• the first Faraday rotator is configured to rotate the polarization direction of the first crystal forward o-light and the first crystal forward e-light by an angle of α1 in the first rotation direction, and then output them to the second birefringent crystal, where α1=45°;
• the second birefringent crystal is configured to cause the first crystal forward o-light to generate a second displacement of the first crystal forward o-light, and the first crystal forward e-light to generate a second displacement of the first crystal forward e-light, and then output them to the second Faraday rotator;
• the second Faraday rotator is configured to rotate the polarization direction of the first crystal forward o-light and the first crystal forward e-light by an angle of α2 in the second rotation direction, and then output them to the third birefringent crystal, where α2=45°;
• the third birefringent crystal is configured to cause the first crystal forward o-light to generate a third displacement of the first crystal forward o-light, and the first crystal forward e-light to generate a third displacement of the first crystal forward e-light;
• wherein a sum of the first displacement of the first crystal forward o light, the second displacement of the first crystal forward o light, and the third displacement of the first crystal forward o light is equal to a sum of the first displacement of the first crystal forward e light, the second displacement of the first crystal forward e light, and the third displacement of the first crystal forward e light, and the first crystal forward o light and the first crystal forward e light are coincident with each other in response to exiting from the third birefringent crystal;
• the third birefringent crystal in the optical isolator core is configured to output the recombined beam of the first crystal forward o-light and the first crystal forward e-light to the lens, the lens is configured to convert the recombined divergent beam into convergent beam and output it to the output waveguide, and the output waveguide is configured to export the convergent beam;
• wherein in the case that backward light entering backward along the forward optical path is incident on the third birefringent crystal, the third birefringent crystal is configured to separate the backward light into a third crystal backward o light and a third crystal backward e light whose polarization directions are perpendicular to each other, and then output them to the second Faraday rotator, such that the third crystal backward o light and the third crystal backward e light respectively generate a third displacement of the third crystal backward o light and a third displacement of the third crystal backward e light;
• the second Faraday rotator is configured to rotate the polarization directions of the third crystal backward o light and the third crystal backward e light by an angle of α2 in the second rotation direction, and then output them to the second birefringent crystal;
• the second birefringent crystal is configured to cause the third crystal backward o light to generate a second displacement of the third crystal backward o light, and the third crystal backward e light to generate a second displacement of the third crystal backward e light, and then output them to the first Faraday rotator;
• the first Faraday rotator is configured to rotate the polarization directions of the third crystal backward o light and the third crystal backward e light by an angle of α1 in the first rotation direction, and then output them to the first birefringent crystal;
• the first birefringent crystal is configured to cause the third crystal backward o light to generate a first displacement of the third crystal backward o light, and the third crystal backward e light to generate a first displacement of the third crystal backward e light;
• wherein a sum of the first displacement of the third crystal backward o light, the second displacement of the third crystal backward o light, and the third displacement of the third crystal backward o light causes the third crystal backward o light to deviate from the forward optical path, and a sum of the first displacement of the third crystal backward e light, the second displacement of the third crystal backward e light, and the third displacement of the third crystal backward e light causes the third crystal backward e light to deviate from the forward optical path, to prevent backward light from coupling into the input waveguide.