Semiconductor laser device

A semiconductor laser device comprising:

• a semiconductor substrate;
• and
• a plurality of semiconductor layers including a first clad layer, a first optical guide layer, an active layer, a second optical guide layer and a second clad layer, the plurality of semiconductor layers being laminated on the substrate in this order,
• wherein a refrative index of the first optical guide layer is higher than a refractive index of the second optical guide layer.

A semiconductor laser device comprising:

• a semiconductor substrate;
• a lower semiconductor layer formed on the substrate, the lower semiconductor layer having a first refractive index;
• an active layer formed on the lower semiconductor layer;
• and
• an upper semiconductor layer formed on the active layer, the upper semiconductor layer having a second refractive index,
• wherein the semiconductor layer that has the higher refractive index is thicker than the other semiconductor layer.

A semiconductor laser device comprising:

• a semiconductor substrate;
• a first clad layer formed on the substrate and made of AlX1Ga1−X1As;
• a first optical guide layer formed on the first clad layer and made of AlY1Ga1−Y1As;
• an active layer formed on the first optical guide layer;
• a second optical guide layer formed on the active layer and made of AlY2Ga1−Y2As;
• and
• a second clad layer formed on the second optical guide layer and made of AlX2Ga1−X2As;
• an insulation layer on one surface of at least one of the layers,
• wherein one of the following relations exists among aluminum-mixing ratios, X1, Y2, Y1 and Y2:
• Y1<Y2<X1<X2, and Y2<Y1<X2<X1.

A semiconductor laser device comprising:

• a semiconductor substrate;
• a first clad layer formed on the substrate and made of AlX1Ga1−X1As;
• a first optical guide layer formed on the first clad layer and made of AlY1Ga1−Y1As;
• an active layer formed on the first optical guide layer;
• a second optical guide layer formed on the active layer and made of AlY2Ga1−Y2As;
• a second clad layer formed on the second optical guide layer and made of AlX2Ga1−X2As;
• and
• an insulation layer located on one surface of at least one of the layers,
• wherein the aluminum-mixing ratio YI continuously varies between the aluminum-mixing ratio in the active layer and the aluminum-mixing ratio X1 in the first clad layer,
• wherein the aluminum-mixing ratio Y2 continuously varies between the aluminum-mixing ratio in the active layer and the aluminum-mixing ratio X2 in the second clad layer, and
• wherein X1≠X2.

A semiconductor laser device comprising:

• a semiconductor substrate;
• a lower semiconductor layer formed on the substrate;
• an active layer formed on the lower semiconductor layer;
• an upper semiconductor layer formed on the active layer;
• and
• an insulation layer located on one surface of at least one of the layers,
• wherein one of the lower semiconductor layer and the upper semiconductor layer has a higher refractive index than the other semiconductor layer, and
• wherein a density peak of a light generated in the active layer appears in the one of the lower semiconductor layer and the upper semiconductor layer.

A semiconductor laser device comprising:

• a semiconductor substrate;
• a lower semiconductor layer formed on the substrate;
• an active layer formed on the lower semiconductor layer;
• an upper semiconductor layer formed on the active layer;
• and
• an insulation film formed to cover at least one side of the active layer,
• wherein one of the lower semiconductor layer and the upper semiconductor layer has a higher refractive index than the other, and
• wherein the semiconductor layer that has the higher refractive index is thicker than the other semiconductor layer.

A semiconductor laser device comprising:

• a semiconductor substrate;
• a lower semiconductor layer formed on the substrate;
• an active layer formed on the lower semiconductor layer;
• an upper semiconductor layer formed on the active layer;
• an insulation film formed to cover sides of the layers;
• and
• end surfaces defining a longitudinal dimension of the laser device and a resonant cavity of laser light generated in the active layer, wherein:
• the active layer uniformly extends between the sides covered by the insulation film and between the end surfaces, a refractive index of the active layer being uniform in an area thereof,
• one of the lower semiconductor layer and the upper semiconductor layer has a higher refractive index than the other, and
• the semiconductor layer that has the higher refractive index is thicker than the other semiconductor layer.

A semiconductor laser device comprising:

• a semiconductor substrate;
• and
• a plurality of semiconductor layers including a first clad layer, a first optical guide layer, an active layer, a second optical guide layer and a second clad layer, the plurality of semiconductor layers being laminated on the substrate in this order, wherein:
• a refractive index of one of the layers located on a first surface of the active layer is different from a refractive index of one of the layers located on a second surface of the active layer, the layer having a higher refractive index being thicker than the layer having a lower refractive index.