Patent ID: 8755422
Filing Date: 2014-06-17
Classification: G02B,H01S

Abstract:
1. A surface emitting laser comprising: a substrate; a lower multilayer mirror and an upper multilayer mirror of a periodic structure of a high refractive index layer and a low refractive index layer formed on the substrate; a first-conductivity-type contact layer and a second-conductivity-type contact layer formed between the lower multilayer mirror and the upper multilayer mirror; an active layer formed between the first-conductivity-type contact layer and the second-conductivity-type contact layer; a current confinement layer formed between the second-conductivity-type contact layer and the active layer and including a current injection portion and a current confinement portion surrounding the current injection portion; a first composition gradient layer and a second composition gradient layer formed facing each other across the current confinement layer, the first composition gradient layer being arranged on the second-conductivity-type contact layer side and the second composition gradient layer being arranged on the active layer side; a second-conductivity-type cladding layer formed between the second composition gradient layer and the active layer; a first-conductivity-type side electrode formed on the first-conductivity-type contact layer; and a second-conductivity-type side electrode formed on the second-conductivity-type contact layer, wherein the first composition gradient layer and the second composition gradient layer are formed such that bandgap energy of each of the layers is monotonically decreased from the current confinement layer to an adjacent layer and approach bandgap energy of the adjacent layer in a growth direction, the second-conductivity-type cladding layer includes material for reducing mobility of carrier, and carrier concentration of the second composition gradient layer is equal to or more than four times that of the carrier concentration of the current injection portion of the current confinement layer, the carrier concentration of the second composition gradient layer is equal to or more than 4×10 layers from the first-conductivity-type contact layer to the second-conductivity-type contact layer except for the active layer are formed of a material chosen from AlGaAs-based, GaInAs-based, AlGaInAs-based, and InP-based semiconductor materials.