Abstract: A bandpass filter includes a combination of a BAW filter and a patterned planar filter with stubs. The BAW filter is composed of a plurality of piezoelectric resonators to give a specific frequency bandpass, while the planer filter is configured to attenuate frequencies near and outside the bandpass. The resonators are connected in a ladder configuration between a first signal transmission path and a ground. The planar filter includes a strip line formed on a dielectric layer to define a second signal transmission path. The BAW filter and the planar filter are formed on a common substrate with the first and second transmission paths connected to each other. The BAW filter, in combination with the patterned planar filter added with the stub, can improve a deep near-band rejection inherent to the BAW filter, exhibiting an excellent out-of-band rejection over certain adjacent frequency ranges outside of the bandpass, and therefore give a sharp and wide bandpass.

Abstract: A bandpass filter includes a combination of a BAW filter and a patterned planar filter with stubs. The BAW filter is composed of a plurality of piezoelectric resonators to give a specific frequency bandpass, while the planer filter is configured to attenuate frequencies near and outside the bandpass. The resonators are connected in a ladder configuration between a first signal transmission path and a ground. The planar filter includes a strip line formed on a dielectric layer to define a second signal transmission path. The BAW filter and the planar filter are formed on a common substrate with the first and second transmission paths connected to each other. The BAW filter, in combination with the patterned planar filter added with the stub, can improve a deep near-band rejection inherent to the BAW filter, exhibiting an excellent out-of-band rejection over certain adjacent frequency ranges outside of the bandpass, and therefore give a sharp and wide bandpass.

Abstract: A compact, low-consumption optical device using a photonic crystal is provided. This optical device comprises a photonic crystal designed to have a shape of a dispersion surface with a strong direction dependence at a frequency, and light input means for allowing a light beam having a wavelength determined by said frequency to be incident on said photonic crystal at an incident angle determined from a region with a large change of direction dependence in the shape of the dispersion surface according to the law of conservation of momentum. In case of adopting this incident angle, the light beam can be deflected by the photonic crystal at an angle that is from several ten times to several hundred times larger than of the deflection angle obtained by use of a conventional optical material.

Abstract: A compact, low-consumption optical device using a photonic crystal is provided. This optical device comprises a photonic crystal designed to have a shape of a dispersion surface with a strong direction dependence at a frequency, and light input means for allowing a light beam having a wavelength determined by said frequency to be incident on said photonic crystal at an incident angle determined from a region with a large change of direction dependence in the shape of the dispersion surface according to the law of conservation of momentum. In case of adopting this incident angle, the light beam can be deflected by the photonic crystal at an angle that is from several ten times to several hundred times larger than of the deflection angle obtained by use of a conventional optical material.