| 主权项 |
1. A surface emitting laser, comprising:
a substrate; a rear mirror on the substrate; an active layer on the rear mirror; a front mirror on the active layer; and a stepped structure on the front mirror, wherein the stepped structure includes a first portion in a first area defined in a central part of an emission area and a second portion in a second area defined on an outer side of the first area within the emission area, wherein the first portion and the second portion have different thicknesses, wherein the stepped structure includes a first structure comprising a first material having a refractive index n1 that is larger than a refractive index n0 of an environmental medium, wherein, when thicknesses of the first structure in the first area and in the second area are d11 and d12, respectively, the following holds:
|n1(d11−d12)|=λ/4×(2M−1) where M is an integer and λ is an oscillation wavelength of the surface emitting laser, and wherein, in terms of an optical path length from a plane, that is defined above the stepped structure and is extending parallel to the substrate, to an interface between the front mirror and the stepped structure, an optical path length L1 in the first area and an optical path length L2 in the second area satisfy the following expression with respect to an integer N that minimizes |L2−L1−Nλ|:
|L2−L1−Nλ|<(λ/4)×(1−n0/n1). |
