A vertical cavity surface-emitting laser comprising: a substrate having a main surface comprising a III-V group compound semiconductor; and a post structure including an active layer and a carrier confinement structure that are arranged in a direction along a first axis crossing the main surface of the substrate, wherein the post structure is mounted on the substrate, the carrier confinement structure includes a first region and a second region, the first region having a lower resistivity than the second region, the first region and the second region being arranged in a first reference plane (R1EF) crossing the direction along the first axis AX1), the first region has an edge, a first length (L1G), a second length (L2G), and a third length (L3G), the edge has a first portion (SDR1a) and a second portion (SDR1b), the first length (L1G) is a length of a first reference line segment (L1N), the first reference line segment (L1N) joining a first point and a second point on the edge, the first reference line segment (L1N) being longest one of a first set of line segments joining any two points on the edge and extending in a direction of the III-V group compound semiconductor, the second length (L2G) is a length of a second reference line segment (L2N), the second reference line segment (L2N) joining a point on the first portion (SDR1a) of the edge and a point on the first reference line segment (L1N), the second reference line segment (L2N) making a right angle with the first reference line segment (L1N), the third length (L3G) is a length of a third reference line segment (L3N), the third reference line segment (L3N) joining a point on the second portion (SDR1b) of the edge and a point on the first reference line segment (L1N), the third reference line segment (L3N) making a right angle with the first reference line segment (L1N), the first length (L1G) is greater than a sum of the second length (L2G) and the third length (L3G), the third length (L3G) is smaller than the second length (L2G) and is zero or more, the second reference line segment (L2N) and the third reference line segment (L3N) lie on a single straight line wherein the second reference line segment (L2N) extends to a midpoint of the first reference line segment (L1N), characterized in that, the single straight line coincides with a single axis of symmetry of the first region of the carrier confinement structure, the post structure has an edge, and the edge of the post structure shares the single axis of symmetry with the edge of the first region of the carrier confinement structure. a substrate having a main surface comprising a III-V group compound semiconductor; and a post structure including an active layer and a carrier confinement structure that are arranged in a direction along a first axis crossing the main surface of the substrate, wherein the post structure is mounted on the substrate, the carrier confinement structure includes a first region and a second region, the first region having a lower resistivity than the second region, the first region and the second region being arranged in a first reference plane (R1EF) crossing the direction along the first axis AX1), the first region has an edge, a first length (L1G), a second length (L2G), and a third length (L3G), the edge has a first portion (SDR1a) and a second portion (SDR1b), the first length (L1G) is a length of a first reference line segment (L1N), the first reference line segment (L1N) joining a first point and a second point on the edge, the first reference line segment (L1N) being longest one of a first set of line segments joining any two points on the edge and extending in a direction of the III-V group compound semiconductor, the second length (L2G) is a length of a second reference line segment (L2N), the second reference line segment (L2N) joining a point on the first portion (SDR1a) of the edge and a point on the first reference line segment (L1N), the second reference line segment (L2N) making a right angle with the first reference line segment (L1N), the third length (L3G) is a length of a third reference line segment (L3N), the third reference line segment (L3N) joining a point on the second portion (SDR1b) of the edge and a point on the first reference line segment (L1N), the third reference line segment (L3N) making a right angle with the first reference line segment (L1N), the first length (L1G) is greater than a sum of the second length (L2G) and the third length (L3G), the third length (L3G) is smaller than the second length (L2G) and is zero or more, the second reference line segment (L2N) and the third reference line segment (L3N) lie on a single straight line wherein the second reference line segment (L2N) extends to a midpoint of the first reference line segment (L1N), characterized in that, the single straight line coincides with a single axis of symmetry of the first region of the carrier confinement structure, the post structure has an edge, and the edge of the post structure shares the single axis of symmetry with the edge of the first region of the carrier confinement structure.