Waveguide-type broadband optical isolator
A waveguide-type broadband optical isolator according to the present invention, comprising: a reciprocal phase shifter which makes a phase difference 3π/2 between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with a fundamental operating wavelength λ, and a nonreciprocal phase shifter which provides a phase difference π/2 for forward propagating waves and a phase difference −π/2 for backward propagating waves.
1. A waveguide type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of 3π/2 between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves;
wherein:
said reciprocal phase shifter includes a tapered waveguide in a propagation direction of a light wave and also includes a tapered waveguide in a part of the other one of said first and second waveguides;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
β 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
2. A waveguide type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of (x +¾) ×2βbetween a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with “x” being an integer of zero or more in a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves,
wherein:
said reciprocal phase shifter includes a tapered waveguide in a propagation direction of a light wave and also includes a tapered waveguide in a part of the other one of said first and second waveguides;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
β 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
3. A waveguide-type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of 3π/2 between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves,
wherein:
said reciprocal phase shifter has a predetermined waveguide width which is not less than a waveguide width of said first waveguide or said second waveguide, and has a waveguide effective refractive index changed;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
β 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π,
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
4. A waveguide-type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of (x +¾) ×2π between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with “x” being an integer of zero or more in a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves,
wherein:
said reciprocal phase shifter has a predetermined waveguide width which is not less than a waveguide width of said first waveguide or said second waveguide, and has a waveguide effective refractive index changed;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
β 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π,
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
5. A waveguide-type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of 3π/2 between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves;
wherein:
directions of magnetic field applications to a magneto-optical material of said nonreciprocal phase shifter are opposite;
said reciprocal phase shifter has a predetermined waveguide width which is not less than a waveguide width of said first waveguide or said second waveguide, and has a waveguide effective refractive index changed;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
β 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π,
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
6. A waveguide type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of (x +¾) ×2π between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with “x” being an integer of zero or more in a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves,
wherein:
directions of magnetic field applications to a magneto-optical material of said nonreciprocal phase shifter are opposite;
said reciprocal phase shifter has a predetermined waveguide width which is not less than a waveguide width of said first waveguide or said second waveguide, and has a waveguide effective refractive index changed;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
β 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π,
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
7. A waveguide type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of 3π/2 between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves;
wherein:
directions of magnetic field applications to a magneto-optical material of said nonreciprocal phase shifter are opposite;
said reciprocal phase shifter includes a tapered waveguide in a propagation direction of a light wave and also includes a tapered waveguide in a part of the other one of said first and second waveguides;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
B 1 ×L 1 −β 2 ×L 2 =( x +¾)×2π,
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.
8. A waveguide-type broadband optical isolator, comprising:
a reciprocal phase shifter which makes a phase difference of (x +¾) ×2π between a first light wave propagating through a first waveguide and a second light wave propagating through a second waveguide, with “x” being an integer of zero or more in a fundamental operating wavelength λ; and
a nonreciprocal phase shifter which provides a phase difference of π/2 for forward propagating waves and a phase difference of −π/2 for backward propagating waves,
wherein:
directions of magnetic field applications to a magneto-optical material of said nonreciprocal phase shifter are opposite;
said reciprocal phase shifter includes a tapered waveguide in a propagation direction of a light wave and also includes a tapered waveguide in part of the other one of said first and second waveguides;
said first waveguide includes said reciprocal phase shifter;
said second waveguide has an adjustment section for adjusting a phase shift by said reciprocal phase shifter; and
said adjustment section has an optical path length L 2 and a waveguide propagation constant β 2 satisfying a formula
B 1 ×L 1−β 2 ×L 2 =( x + ¾)×2π,
wherein “L 0 ” is an optical path length between branching/coupling devices of said first waveguide which does not include said reciprocal phase shifter, “β 2 ” is a propagation constant, “L 1 ” is an optical path length of said reciprocal phase shifter, “β 1 ” is a propagation constant, and “x” is an integer of zero or more.