Monitoring of optical radiation in semiconductor devices

An optical amplifier, comprising:

• an optical gain region which is adapted to output amplified optical radiation responsive to a current injected into the section;
• a waveguide having a first refractive index, coupled to receive the amplified optical radiation, and comprising a curved section having a predetermined radius of curvature, which is adapted to leak a predetermined fraction of the amplified optical radiation to a region adjoining the waveguide which has a second refractive index different from the first refractive index;
• and
• a photodetector which receives at least some of the leaked optical radiation and which generates a monitoring signal responsive thereto, indicative of a performance characteristic of the optical gain region.

A method for monitoring optical radiation, comprising:

• inputting the optical radiation into a waveguide having a first refractive index;
• forming the waveguide as a curved waveguide having a predetermined radius of curvature so that a predetermined fraction of the optical radiation leaks from the waveguide to a region adjoining the waveguide which has a second refractive index different from the first refractive index;
• and
• measuring the leaked optical radiation so as to monitor a characteristic of the radiation in the waveguide.

A method for amplifying optical radiation, comprising:

• injecting current into an optical gain region so as to engender amplification of the optical radiation in the region;
• coupling the amplified optical radiation into a waveguide having a first refractive index;
• forming the waveguide as a curved waveguide having a predetermined radius of curvature so that a predetermined fraction of the amplified optical radiation leaks from the waveguide to a region adjoining the waveguide which has a second refractive index different from the first refractive index;
• and
• generating a monitoring signal, indicative of a performance characteristic of the optical gain region, responsive to the leaked optical radiation.