Optical chip, external cavity laser, laser module and laser sensing system

The embodiment of the invention discloses an optical chip, an external cavity laser, a laser module and a laser sensing system, relates to the field of lasers, and solves the problem of low self-injection locking optical power of a micro-ring external cavity reflected back to a gain chip in an integrated micro-ring external cavity narrow linewidth laser. The optical chip comprises a substrate and a waveguide layer arranged on the substrate. The waveguide layer forms a first optical waveguide, a bidirectional power beam splitting element with a first port, a second port and a third port, a second optical waveguide, a reflecting element and a micro-ring optical waveguide. A first end of the first optical waveguide is coupled or connected with an end face of a gain chip in the laser, and a second end of the first optical waveguide is connected with a first port of the bidirectional power beam splitting element. The micro-ring optical waveguide is located on one side of the first optical waveguide. One end of the second optical waveguide is connected with a second port of the bidirectional power beam splitting element. The other end of the second optical waveguide extends to the other side, away from the first optical waveguide, of the micro-ring optical waveguide and is connected with the reflecting element. The first optical waveguide and the second optical waveguide are coupled with the micro-ring optical waveguide.