Method and apparatus for adding/droping optical signals in a semiconductor substrate

An apparatus, comprising:

• first and second 3 dB optical couplers disposed in a semiconductor substrate, the first 3 dB optical coupler optically coupled to receive a first optical beam and split the first optical beam into second and third optical beams having an approximately π/2 phase difference, the second optical coupler optically coupled to receive the second and third optical beams and output a fourth optical beam;
• and
• first and second tunable Bragg gratings disposed in the semiconductor substrate having respective optical paths through which the second and third optical beams are optically coupled to propagate between the first and second 3 dB optical couplers, the first and second tunable Bragg gratings each including a plurality of silicon and polysilicon interfaces along the respective optical paths such that there are a plurality of perturbations of a refractive index of the semiconductor substrate along the respective optical paths, the plurality of silicon and polysilicon interfaces oriented substantially perpendicular to the semiconductor substrate, the first and second tunable Bragg gratings optically coupled to reflect back to the first 3 dB optical coupler a portion of the second and third optical beams having a tunable wavelength.

An apparatus, comprising:

• first and second 3 dB optical couplers disposed in a semiconductor substrate, the first 3 dB optical coupler optically coupled to receive a first optical beam and split the first optical beam into second and third optical beams having an approximately π/2 phase difference, the second optical coupler optically coupled to receive the second and third optical beams and output a fourth optical beam;
• and
• first and second tunable Bragg gratings disposed in the semiconductor substrate having respective optical paths through which the second and third optical beams are optically coupled to propagate between the first and second 3 dB optical couplers, the first and second tunable Bragg gratings each including a plurality of charge modulated regions along the respective optical paths to establish a plurality of perturbations of a refractive index of the semiconductor substrate along the respective optical paths, the first and second tunable Bragg gratings optically coupled to reflect back to the first 3 dB optical coupler a portion of the second and third optical beams having a tunable wavelength.

An apparatus, comprising:

• a first 3 dB optical coupler disposed in a semiconductor substrate, the first 3 dB optical coupler optically coupled to receive a first optical beam and split the first optical beam into second and third optical beams having an approximately π/2 phase difference;
• and
• first and second tunable Bragg gratings disposed in the semiconductor substrate having respective optical paths through which the second and third optical beams are optically coupled to propagate from the first 3 dB optical couplers to the first and second tunable Bragg gratings, the first and second tunable Bragg gratings each including a plurality of silicon and polysilicon interfaces along the respective optical paths such that there are a plurality of perturbations of a refractive index of the semiconductor substrate along the respective optical paths, the plurality of silicon and polysilicon interfaces oriented substantially perpendicular to the semiconductor substrate, the first and second tunable Bragg gratings optically coupled to reflect back to the first 3 dB optical coupler portions of the second and third optical beams having a tunable wavelength, wherein the first 3 dB optical coupler is optically coupled to combine the portions of the second and third optical beams having the tunable wavelength into a fourth optical beam having the tunable wavelength.

An apparatus, comprising:

• a first 3 dB optical couplers disposed in a semiconductor substrate, the first 3 dB optical coupler optically coupled to receive a first optical beam and split the first optical beam into second and third optical beams having an approximately π/2 phase difference;
• and
• first and second tunable Bragg gratings disposed in the semiconductor substrate having respective optical paths through which the second and third optical beams are optically coupled to propagate from the first 3 dB optical couplers to the first and second tunable Bragg gratings, the first and second tunable Bragg gratings each including a plurality of charge modulated regions along the respective optical paths to establish a plurality of perturbations of a refractive index of the semiconductor substrate along the respective optical paths, the first and second tunable Bragg gratings optically coupled to reflect back to the first 3 dB optical coupler portions of the second and third optical beams having a tunable wavelength, wherein the first 3 dB optical coupler is optically coupled to combine the portions of the second and third optical beams having the tunable wavelength into a fourth optical beam having the tunable wavelength.