Semiconductor laser device

A semiconductor laser device, comprising a laser section and a modulator section which are formed on a same semiconductor substrate;

• wherein the laser section has:
• a first mesa stripe which is provided as a mesa formed on the semiconductor substrate and extending in a direction of an optical axis of laser light to be emitted by the laser section, and which includes an active layer;
• semi-insulative burying layers which are placed to abut on both side surfaces of the first mesa stripe and are formed on the semiconductor substrate;
• n-type burying layers formed on respective surfaces of the semi-insulative burying layers;
• and a p-type cladding layer which covers surfaces of the n-type burying layers and the first mesa stripe;
• wherein the modulator section has:
• a second mesa stripe which is provided as a mesa formed on the semiconductor substrate and extending in the direction of the optical axis, and which includes an absorption layer;
• semi-insulative burying layers which are placed to abut on both side surfaces of the second mesa stripe and are formed on the semiconductor substrate;
• and a p-type cladding layer which covers surfaces of the semi-insulative burying layers and the second mesa stripe;
• and
• wherein the separation section has:
• a third mesa stripe which is provided as a mesa formed on the semiconductor substrate and extending in the direction of the optical axis, and which includes an absorption layer;
• semi-insulative burying layers which are placed to abut on both side surfaces of the third mesa stripe and are formed on the semiconductor substrate;
• n-type burying layers which are formed on respective surfaces of the semi-insulative burying layers but are placed only in regions thereon adjacent to the third mesa stripe;
• and a p-type cladding layer which covers surfaces of the semi-insulative burying layers, the n-type burying layers and the third mesa stripe.