Optical modulators and photonic integrated systems

A carrier-injection-based optical modulator, the optical modulator comprising:

• at least two phase shifters;
• wherein each phase shifter includes
• a waveguide channel for transmitting optical signal,
• a P-type doped region and an N-type doped region located on opposite sides of the waveguide channel, and
• an undoped intrinsic region located between the P-type doped region and the N-type doped region in the waveguide channel;
• a blocking structure provided in the ends of the adjacent phase shifters facing each other to block carriers from diffusing from one phase shifter to another phase shifter along the waveguide propagation direction of the waveguide channel;
• and
• a tapered waveguide region provided on both end sides of the intrinsic region of the each phase shifter, wherein the blocking structure is formed in the tapered waveguide region.

A photonic integrated system comprising a carrier-injection-based optical modulator comprising:

• at least one phase shifter including
• a waveguide channel for transmitting optical signal,
• a P-type doped region and an N-type doped region located on opposite sides of the waveguide channel, and
• an undoped intrinsic region located between the P-type doped region and the N-type doped region in the waveguide channel;
• and
• a blocking structure provided at or close to at least one end of the intrinsic region for blocking the diffusion of carriers along the waveguide propagation direction of the waveguide channel, wherein
• the blocking structure comprises a PN junction.