Semiconductor laser device having integral optical output modulator

In a semiconductor laser device:

• a semiconductor laser portion;
• said semiconductor laser portion including
• a semiconductor substrate of a first conductivity type, a first ohmic electrode connected to a surface of said substrate and
• at least one semiconductor laser having a double hetero structure formed on the top surface of said semiconductor substrate of the first conductiveity type;
• and
• at least one vertical field effect transistor portion formed on said semiconductor laser portion for modulating the optical output of said semiconductor laser portion;
• said vertical field effect transistor portion including
• a first semiconductor layer of a second conductivity type which is opposite to said first conductivity type, formed on the top surface of said semiconductor laser portion;
• a second semiconductor layer of the first conductivity type formed on the top surface of said first semiconductor layer;
• and
• a third semiconductor layer of the second conductivity type formed on the top surface of said second semiconductor layer, wherein a striped groove deep enough to reach at least the first semiconductor layer from the top surface of said third semiconductor layer is formed in said first, second and third semiconductor layers;
• a second ohmic electrode connected to a surface of said third semiconductor layer;
• said field effect transistor portion further comprising
• an insulating film formed on the top surface of said striped groove, and
• a gate electrode formed on the top surface of said insulating film.