| 摘要 |
PROBLEM TO BE SOLVED: To increase the degree of freedom in the element design of a single longitudinal mode oscillation semiconductor laser by forming a structure having periodically varying refractive index or a structure having periodically varying laser gain in a light confinement region or a current constriction region. SOLUTION: A light confinement region 52 having a diffraction grating structure 54 is formed on the side face 51 of an active layer 50. Leakage of light 55 from the side face 51 of the active layer 50 is varied drastically by periodic modulation of refractive index caused by the diffraction grating structure 54. Consequently, single mode oscillation is effected. The active layer 50 is independent from the diffraction grating structure 54. More specifically, no periodic conductivity modulation region exist on the current path in a semiconductor laser. Consequently, carriers required for laser emission can be injected effectively into the active layer 50. In other words, a gain coupling part required for single mode oscillation design can be designed independently and the degree of freedom of design is increased.
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