Guided wave optical frequency shifter

A frequency shifter for receiving an optical carrier signal having a carrier frequency and providing a sideband output that is shifted in frequency from the carrier frequency, comprising:

• waveguide means comprising an optical waveguide formed in an electro-optically active material for guiding an optical signal in the electro-optically active material;
• and
• means for forming a rotating half wave retardation waveplate in said waveguide means to shift the frequency of the signal to provide a sideband having a frequency shift dependant upon the rotation rate of said waveplate;
• a first quarter wave retardation plate formed in said waveguide means proximate a first end thereof;
• and
• a second quarter wave retardation plate formed in said waveguide means proximate a second end thereof, said first and second quarter wave retardation plates adjusting the polarization of optical signals input thereto to provide circularly polarized optical signals for input to said rotating half wave retardation waveplate.

A frequency shifter for shifting the frequency of an optical carrier from a carrier frequency to a sideband frequency, comprising:

• a substrate formed of an electro-optically active material;
• an optical waveguide formed in said substrate;
• a first electrode attached to a surface of said substrate, said first electrode covering a length of said optical waveguide;
• a second electrode attached to the surface of said substrate proximate said first electrode;
• a third electrode attached to said substrate;
• means for applying a first voltage between said first electrode an said second electrode to form a first electric field through said optical waveguide;
• and
• means for applying a second voltage between said second electrode and said third electrode to form a second electric field through said optical waveguide and perpendicular to said first electric field, the first and second voltages having a phase difference of 90 degrees so that the resultant of said first and second electric fields is a rotating electric field vector in said length of optical waveguide.

A frequency shifter for shifting the frequency of an optical carrier signal from a carrier frequency to a sideband frequency, comprising:

• an optical waveguide formed in an electro-optically active material;
• means for introducing an single made optical carrier signal into said optical waveguide;
• and
• means for inducing a rotating birefringence in said optical waveguide, said rotating birefringence shifting the frequency of said carrier signal by an amount dependent upon the rotation rate of said rotating birefringence.

A method for shifting the frequency of an optical carrier signal from a carrier frequency to a sideband frequency, comprising the steps of:

• forming an optical waveguide in an electro-optically active material;
• introducing an optical signal comprising a single mode of electromagnetic energy at the carrier frequency into the optical waveguide;
• and
• forming a rotating waveplate in a length of the optical waveguide.

A method for shifting the frequency of an optical carrier signal from a carrier frequency to a sideband frequency, comprising the steps of:

• forming an optical waveguide in an electro-optically active material;
• forming a rotating half waveplate in a length of the optical waveguide to cause halfwave retardation in the carrier signal by the steps of;
• depositing a first electrode on the substrate over a length of the optical waveguide;
• depositing a second electrode on the substrate spaced apart from the first electrode on a first side thereof;
• depositing a third electrode on the substrate spaced apart from the first electrode on a second side thereof;
• applying a first voltage to the first electrode to form a first electric field through the optical waveguide;
• applying a second voltagel between the second electrode and the third electrode to form a second electric field to the optical waveguide perpendicular to the first electric field with the same magnitude as the first electric field, the first and second voltages having a phase difference of 90.degree. so that the resultant field rotates relative to the optical waveguide;
• and
• forming a quarter waveplate in the optical waveguide to circularly polarize the optical carrier signal input to the half waveplate.

A method for shifting the frequency of an optical carrier signal from a carrier frequency to a sideband frequency, comprising the steps of:

• forming an optical waveguide in an electro-optically active material;
• introducing a single mode optical carrier signal into the optical waveguide;
• and
• inducing a rotating birefringence in said optical waveguide to shift the carrier signal to a sideband frequency that is dependent upon the rotation rate of the birefringence.

A method for forming an optical frequency shifter, comprising the steps of:

• forming an optical waveguide in an electro-optically active substrate;
• forming a first electrode on a surface of the substrate adjacent a length of the optical waveguide;
• forming a second electrode on the surface of the substrate spaced apart from and generally parallel to the length of the optical waveguide;
• forming a third electrode on the surface of the substrate spaced apart from and generally parallel to the length of the optical waveguide;
• applying a first voltage to the first electrode to form a first electric field through the optical waveguide;
• and
• applying a second voltage to the second and third electrodes 90 degrees out of phase with the first voltage to form a second electric field perpendicular to the first electric field so that the resultant electric field applied to the optical waveguide rotates at a predetermined rate about the optical waveguide.

A method for forming an optical frequency shifter, comprising the steps of:

• forming an optical waveguide in an electro-optically active substrate;
• forming a first electrode on a surface of the substrate adjacent a length of the optical waveguide;
• forming a second electrode on the surface of the substrate spaced apart from and generally parallel to the length of the optical waveguide;
• forming a third electrode on the substrate spaced apart from and parallel to the optical waveguide;
• applying a first voltage to the first electrode to form a first electric field through the optical waveguide;
• 90.degree. out of phase with the first voltage to form a second electric field perpendicular to the first electric field so that the resultant electric field applied to the optical waveguide rotates at a predetermined rate about the optical waveguide;
• connecting the third electrode at ground potential so that the first electric field extends between the first and third electrodes and the second electric field extends between the second and third electrodes;
• forming a first quarter waveplate in the substrate adjacent a first end of the second electrode;
• and
• forming a second quarter waveplate in the substrate adjacent the other end of the second electrode to ensure that the optical signal incident upon the length of the optical waveguide under the second electrode is circularly polarized.

A method for shifting the frequency of an optical carrier signal having a carrier frequency to a sideband frequency comprising the steps of:

• forming a waveguide in an electro-optically active material for guiding an optical signal in the electro-optically active material;
• and
• forming a rotating half wave retardation waveplate in said waveguide means to shift the frequency of the signal to provide a sideband having a frequency shift dependant upon the rotation rate of said waveplate;
• forming a first quarter wave retardation plate formed in said waveguide means proximate a first end thereof;
• and
• forming a second quarter wave retardation plate formed in said waveguide means proximate a second end thereof, said first and second quarter wave retardation plates adjusting the polarization of optical signals input thereto to provide circularly polarized optical signals for input to said rotating half wave retardation waveplate.