US 7,321,707 B2
Electromagnetic wave frequency filter
Susumu Noda, Uji (Japan); Takashi Asano, Kyoto (Japan); Bong-Shik Song, Kyoto (Japan); and Hitomichi Takano, Hirakata (Japan)
Assigned to Japan Science and Technology Agency, Kawaguchi-shi (Japan); and Matsushita Electric Works, Ltd., Osaka (Japan)
Appl. No. 10/569,922
PCT Filed Aug. 26, 2004, PCT No. PCT/JP2004/012287
§ 371(c)(1), (2), (4) Date Feb. 28, 2006,
PCT Pub. No. WO2005/022221, PCT Pub. Date Mar. 10, 2005.
Claims priority of application No. 2003-307266 (JP), filed on Aug. 29, 2003.
Prior Publication US 2006/0269188 A1, Nov. 30, 2006
Int. Cl. G02B 6/26 (2006.01)
U.S. Cl. 385—50  [385/14; 385/129] 16 Claims
OG exemplary drawing
 
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 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 said input-waveguide-side reflector and returned to near said resonator, θ2 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.