Electromagnetic wave frequency filter
First Claim
1. An electromagnetic wave frequency filter comprising:
- an input waveguide configured to receive electromagnetic waves of a plurality of frequencies inputted into a one end of said input waveguide;
an output waveguide disposed alongside said input waveguide; and
a resonator disposed between said input waveguide and said output waveguide, said resonator having a resonant frequency and resonating with an electromagnetic wave of a predetermined frequency matching the resonant frequency so as to transmit said electromagnetic wave from said input waveguide to said output waveguide, thereby allowing said electromagnetic wave to be emitted from a drop port of a one end of said output waveguide,whereinsaid input waveguide has an input-waveguide-side reflector for reflecting said electromagnetic wave of the resonant frequency on the opposite side of said one end of the input waveguide from the resonator,said output waveguide having an output-waveguide-side reflector for reflecting the electromagnetic wave of the predetermined frequency on the opposite side of said one end of the output waveguide,said electromagnetic wave frequency filter satisfying the following relation;
Qinb/(1 cos θ
1)<
<
Qv,
Qinb/(1 cos θ
1)=Qinr/(1 cos θ
2),
θ
1, θ
2≠
2Nπ
(N=0, 1, . . . ),where θ
1 is a phase shift amount of the electromagnetic wave reflected by said input-waveguide-side reflector and returned to near said resonator, θ
2 is a phase shift amount of the electromagnetic wave reflected by said output-waveguide-side reflector and returned to near said resonator, Qinb is a Q-factor between said resonator and said input waveguide, Qinr is a Q-factor between said resonator and said output waveguide, and Qv is a Q-factor between said resonator and free space.
2 Assignments
0 Petitions
Accused Products
Abstract
In this electromagnetic wave frequency filter, an electromagnetic wave of a predetermined frequency matching a resonant frequency of a resonator 41 is transmitted from an input waveguide 2 to an output waveguide 3 through the resonator 41, and is outputted from a drop port P31. This filter has an input-waveguide-side reflector 211 and an output-waveguide-side reflector 311, which reflect the electromagnetic wave of the predetermined frequency. The electromagnetic wave frequency filter satisfies the following relation:
Qinb/(1−cos θ1)<<Qv,
Qinb/(1−cos θ1)=Qinr/(1−cos θ2),
θ1, θ2≠2Nπ(N=0, 1, . . . ),
where θ1 is a phase shift amount of the electromagnetic wave reflected by the input-waveguide-side reflector 211, θ2 is a phase shift amount of the electromagnetic wave reflected by the output-waveguide-side reflector 311, Qinb is a Q-factor between the resonator 41 and the input waveguide 2, Qinr is a Q-factor between the resonator 41 and the output waveguide 31, and Qv is a Q-factor between the resonator 41 and free space.
-
Citations
16 Claims
-
1. An electromagnetic wave frequency filter comprising:
-
an input waveguide configured to receive electromagnetic waves of a plurality of frequencies inputted into a one end of said input waveguide; an output waveguide disposed alongside said input waveguide; and a resonator disposed between said input waveguide and said output waveguide, said resonator having a resonant frequency and resonating with an electromagnetic wave of a predetermined frequency matching the resonant frequency so as to transmit said electromagnetic wave from said input waveguide to said output waveguide, thereby allowing said electromagnetic wave to be emitted from a drop port of a one end of said output waveguide, wherein said input waveguide has an input-waveguide-side reflector for reflecting said electromagnetic wave of the resonant frequency on the opposite side of said one end of the input waveguide from the resonator, said output waveguide having an output-waveguide-side reflector for reflecting the electromagnetic wave of the predetermined frequency on the opposite side of said one end of the output waveguide, said electromagnetic wave frequency filter satisfying the following relation;
Qinb/(1 cos θ
1)<
<
Qv,
Qinb/(1 cos θ
1)=Qinr/(1 cos θ
2),
θ
1, θ
2≠
2Nπ
(N=0, 1, . . . ),where θ
1 is a phase shift amount of the electromagnetic wave reflected by said input-waveguide-side reflector and returned to near said resonator, θ
2 is a phase shift amount of the electromagnetic wave reflected by said output-waveguide-side reflector and returned to near said resonator, Qinb is a Q-factor between said resonator and said input waveguide, Qinr is a Q-factor between said resonator and said output waveguide, and Qv is a Q-factor between said resonator and free space.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
an amount of axis misalignment between the portion of the input waveguide formed in the first two-dimensional photonic crystal and the portion of the input waveguide formed in the second two-dimensional photonic crystal and an amount of axis misalignment between the portion of the output waveguide formed in the first two-dimensional photonic crystal and the portion of the output waveguide formed in the second two-dimensional photonic crystal being set equal to each other so as to make a reflection phase shift Δ
1 of the electromagnetic wave reflected by said input-waveguide-side reflector and a reflection phase shift Δ
2 of the electromagnetic wave reflected by said output-waveguide-side reflector equal to each other.
-
-
4. The electromagnetic wave frequency filter as set forth in claim 3, wherein a period of the refractive-index periodic structure of at least one of said first two-dimensional photonic crystal and said second two-dimensional photonic crystal near a boundary between the first photonic crystal and the second photonic crystal is changed in stages so that the input waveguide extends smoothly and continuously near the boundary.
-
5. The electromagnetic wave frequency filter as set forth in claim 3, wherein relative positions of said first photonic crystal and said second photonic crystal in an arranging direction of said input waveguide and said output waveguide are set so that the axis misalignment of said input waveguide is not generated between said first photonic crystal and said second photonic crystal,
the distance between the resonator and the input-waveguide-side reflector being set so that a relation cos θ -
1=cos θ
2 is satisfied.
-
1=cos θ
-
6. The electromagnetic wave frequency filter as set forth in claim 3, wherein relative positions of said first photonic crystal and said second photonic crystal in an arranging direction of said input waveguide and said output waveguide are set so that the axis misalignment of the input waveguide is not generated between said first photonic crystal and said second photonic crystal,
said output-waveguide-side reflector having a phase compensator for matching Δ -
2 to Δ
1.
-
2 to Δ
-
7. The electromagnetic wave frequency filter as set forth in claim 1, wherein said electromagnetic wave frequency filter has an in-plane heterostructure in which at least a first photonic crystal having a refractive-index periodic structure in a two-dimensional plane and a second photonic crystal having a refractive-index periodic structure whose period is different from that of the refractive-index periodic structure of the first photonic crystal are placed side by side in the same plane,
said input waveguide being formed by creating a linear defect in the refractive-index periodic structures of the first and second photonic crystals along the entire length thereof in an arranging direction of these photonic crystals, said resonator being formed by creating a pot-like defect in said first photonic crystal, said output waveguide being formed by creating a linear defect in the refractive-index periodic structure of said first photonic crystal, said output-waveguide-side reflector being constituted by an opposite end of said output waveguide. -
8. The electromagnetic wave frequency filter as set forth in claim 7, wherein said first photonic crystal and said second photonic crystal each are a two-dimensional photonic crystal,
a distance d1 between said resonator and said input-waveguide-side reflector in a direction along said input waveguide and a distance d2 between said resonator and said output-waveguide-side reflector in a direction along said output waveguide being set so that a relation cos θ -
1=cos θ
2 is satisfied.
-
1=cos θ
-
9. The electromagnetic wave frequency filter as set forth in claim 8, wherein the refractive-index periodic structure of said first photonic crystal is varied so that electromagnetic field distribution near the opposite end of said output waveguide does not change abruptly.
-
10. The electromagnetic wave frequency filter as set forth in claim 1, wherein
Qinb, Qinr, cos θ -
1, and cos θ
2 satisfy the following relations;
Qinb=Qinr
cos θ
1=cos θ
2.
-
1, and cos θ
-
11. The electromagnetic wave frequency filter as set forth in claim 1, further comprising
a control means for changing an output of the drop port by varying a refractive index near at least one of said input-waveguide-side reflector and said output-waveguide-side reflector. -
12. The electromagnetic wave frequency filter as set forth in claim 2, further comprising
a control means for changing an output of the drop port by varying a period of the refractive-index periodic structure near at least one of said input-waveguide-side reflector and said output-waveguide-side reflector. -
13. The electromagnetic wave frequency filter as set forth in claim 1, further comprising
a control means for changing an output of the drop port by varying a refractive index near said output-waveguide-side reflector. -
14. The electromagnetic wave frequency filter as set forth in claim 1, wherein
Qinb and Qinr are different from each other, said electromagnetic wave frequency filter further comprising a control means for changing an output of the drop port by varying a refractive index near said output-waveguide-side reflector. -
15. The electromagnetic wave frequency filter as set forth in claim 1, further comprising
a control means for changing an output of the drop port by varying a refractive index near said input-waveguide-side reflector, said output-waveguide-side reflector, and said reflector each. -
16. The electromagnetic wave frequency filter as set forth in claim 7, further comprising
a control means for changing an output of the drop port by varying a period of the refractive-index periodic structure near at least one of said input-waveguide-side reflector and said output-waveguide-side reflector.
Specification