Semiconductor laser element

A semiconductor laser element comprising:

• a substrate having a projection at an upper face thereof;
• a first semiconductor layer disposed above the substrate;
• a light emission layer disposed above the first semiconductor layer;
• a second semiconductor layer disposed above the light emission layer;
• and
• a low refractive index part having a refractive index lower than that of the first semiconductor layer, wherein
• the second semiconductor layer has a ridge part for guiding laser light generated in the light emission layer,
• a width of the ridge part cyclically changes in accordance with a position in a waveguiding direction of the ridge part,
• an angle between a side face of the ridge part and the waveguiding direction is larger than a limit angle defined by an effective refractive index on each of an inner side of the ridge part and an outer side of the ridge part, and
• the low refractive index part is disposed between an active layer of the light emission layer and the projection of the substrate, and on the outer side of the side face at least where the width of the ridge part is small.