Surface emitting laser, surface-emitting-laser array, and image forming apparatus

摘要

The present invention provides a surface emitting laser that provides a sufficient optical output and is suitable as a light source intended for electrophotographic apparatuses, and a surface-emitting-laser array and an image forming apparatus each including the surface emitting laser. The surface emitting laser includes a first stepped structure on a front surface of a front mirror. In the first stepped structure, a difference L between an optical path length in a first area and an optical path length in a second area satisfies the following expression:
(¼+N)λ<|L|<(¾+N)λ
where N is an integer.

主权项

1. A surface emitting laser configured to oscillate at a wavelength λ, comprising:
a substrate; a multilayer structure provided on the substrate and in which layers including a rear mirror, an active layer, and a front minor are stacked; a first stepped structure provided over a front surface of the front mirror and including a first portion extending in a first area defined in a central part of an emission area and a second portion extending in a second area defined on the outer side of the first area within the emission area, the first and second portions having different heights; and a second stepped structure provided between the first stepped structure and the front mirror, and including a third portion extending in a third area defined in the central part of the emission area and a fourth portion extending in a fourth area defined on the outer side of the third area, wherein, in terms of an optical path length from a plane defined on the outside of the surface emitting laser and extending perpendicular to a stacking direction of the multilayer structure to the front surface of the front mirror, a difference L between the optical path length in the first area and the optical path length in the second area satisfies the following expression:
(¼+N)λ<|L|<(¾+N)λ where N is an integer, wherein a refractive index of a material forming the second stepped structure is different from a refractive index of a material forming the first stepped structure, and wherein a reflectance of a structure, including the front minor, the first stepped structure and the second stepped structure, is higher in a portion corresponding to the third area than in a portion corresponding to the fourth area.