Surface emitting laser and image forming apparatus

A surface emitting laser comprising:

• a cavity including a first mirror and a second mirror, wherein, in each of the first and second mirrors, first layers with a first refractive index and second layers with a second refractive index higher than the first refractive index are alternately stacked;
• an active layer formed in the cavity;
• and
• a third mirror formed between the first mirror and the active layer, the third mirror having a structure in which third layers with a third refractive index lower than the second refractive index and fourth layers with a fourth refractive index higher than the third refractive index and the first refractive index are alternately stacked,
• wherein, when a first adjacent layer that is included in the first mirror and is closest to the third mirror is one of the first layers, a second adjacent layer that is included in the third mirror and is closest to the first mirror is one of the third layer;
• and
• wherein, when the first adjacent layer is one of the second layers, the second adjacent layer is one of the fourth layers.