Optical semiconductor chip

An optical semiconductor chip, comprising:

• a laser light source having an optical waveguide structure, the structure having a first type semiconductor base layer, an active layer and a second type semiconductor layer arranged in this order;
• an electrode pad receiving a modulation signal;
• a modulation electrode being formed on the second type semiconductor layer;
• and
• a meander wiring connecting the electrode pad and the modulation electrode and providing inductance in series with respect to a depletion layer capacitance of the optical waveguide,
• wherein a portion under the meander wiring and the electrode pad is composed of a material having a dielectric constant lower than a dielectric constant of the semiconductor base layer;
• and
• a thickness of the material is set such that a height of the meander wiring and the electrode pad is higher than a top surface of the optical waveguide.