Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With reflector – opaque mask – or optical element integral...
Reexamination Certificate
2000-03-20
2003-07-01
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With reflector, opaque mask, or optical element integral...
C257S079000, C257S103000, C313S113000
Reexamination Certificate
active
06586775
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light-emitting device to be used for illumination, display, communication, etc., as well as to an illumination apparatus, a display apparatus, and other systems using such a light-emitting device. The present invention also relates to an optoelectronic integrated circuit device formed by integrating a silicon IC and optical elements.
2. Description of the Background Art
Various light-emitting devices are known. However, their luminous efficiency is low, which is a major problem to be solved. Recently, low-power-consumption light sources have been required in connection with environmentally related problems and various technical developments have been made to increase their luminous efficiency. For example, in incandescent lamps, heat-radiation light is mostly infrared light and includes very little visible light, which is the main reason of low efficiency. To increase the efficiency, a measure as shown in
FIG. 18
has been taken in which the glass ball of a lamp is coated with an infrared reflection film referred to as a heat mirror (see Jack Brett et al., “Radiation-conserving Incandescent Lamps”, J. of IES, p. 197, 1980). In
FIG. 18
, reference numeral
1801
denotes a glass ball having a heat mirror and numeral
1802
denotes a tungsten filament.
To increase the feedback ratio, that is, the ratio at which reflected infrared light is absorbed by the filament, fine adjustment of the filament position and other adjustments are necessary. However, the increase in feedback ratio attained by such adjustments is restricted, and hence sufficient improvement cannot be obtained.
A more straightforward measure in which the radiation itself of infrared light from a filament is suppressed has been proposed in U.S. Pat. No. 5,079,473. In this method, as shown in
FIGS. 19A and 19B
, an array of cavity waveguides is provided on the surface of a light-emitting body. In
FIGS. 19A and 19B
, reference numeral
1901
denotes a tungsten filament and numeral
1902
denotes cavities in this method, and the radiation of light in a frequency range that is lower than the cutoff frequency is suppressed by setting the cutoff frequency of the cavity waveguides at a predetermined value.
However, even in this case, infrared light is freely radiated from the regions between adjacent of the cavity waveguides. Decreasing the distance between adjacent cavity waveguides is considered to decrease the area of those regions to thereby reduce infrared radiation. However, this measure has a problem that the cutoff frequency disappears due to coupling of adjacent optical modes, that is, infrared light comes to be radiated freely contrary to the intention.
On the other hand, a display utilizing heat radiation has been reported (see Frederick Hochberg et al., “A Thin-film Integrated Incandescent Display,” IEEE Trans. on Electron. Devices, Vol. ED-20, No. 11, p. 1,002, 1973). That paper reports a display that utilizes heat radiation from tungsten. However, the luminous efficiency of the light-emitting portion is very low because, as described above, heat radiation light includes very little visible light. So the display as a whole has a serious problem in efficiency.
In the field of optical communication, in which lasers and LEDs are used as light sources, simpler, lower-cost light sources have been desired. In the field of silicon ICs and LSIs, the realization of optoelectronic integrated circuits have been desired. However, their application range is limited because no silicon device capable of emitting light efficiently is available, and hence an LSI and a light-emitting element need to be manufactured separately. Further, an increase in the integration density of LSIs and multi-layering of complex electric wiring are major factors that prevent a future increase in the integration density of optoelectronic integrated circuits.
As described above, although various attempts have been made to increase the efficiency of light-emitting devices, they have not succeeded in increasing the characteristic to a large extent. Further, complex electrical wiring of LSIs has prevented an increase in the integration density of optoelectronic integrated circuits.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances in the art, and an object of the present invention is therefore to provide a novel light-emitting device having high luminous efficiency as well as various systems using the novel light-emitting device.
Another object of the present invention is to provide a novel optoelectronic integrated circuit device having optical wiring that replaces complex electric wiring of an LSI.
To attain the above and other objects, the present invention provides the following devices and apparatuses.
One feature of the present invention is that a light-emitting device for radiating visible light includes a light-emitting element configured to radiate first light having an intensity peak within the infrared wavelength region. A photonic crystal structure faces the light-emitting element, and the photonic crystal structure receives the first light from the light-emitting element and transmits the first light to convert the first light into second light having an intensity peak within the visible light wavelength region, and the second light is radiated from the photonic crystal structure as visible light.
A further feature of the present invention is that a light-emitting device for radiating visible light includes a first filament configured to radiate first light having an intensity peak at a first wavelength thereof. A photonic crystal structure is provided surrounding the first filament, and the photonic crystal structure receives the first light from the first filament and transmits the first light to convert the first light into the light having an intensity peak at a second wavelength thereof which is smaller than the first wavelength of the first light, and the second light is radiated from the photonic crystal structure as visible light.
Preferred embodiments of the above present inventions may include the following features (1)-(15).
(1) The photonic crystal structure includes a dielectric layer and metal bodies arranged in the dielectric layer periodically.
(2) Each of the metal bodies is a spherical body.
(3) The dielectric layer is formed of at least one material selected from the group consisting of TiO
2
, SiO
2
, Al
2
O
3
, Si, and ZrO
2
, and the metal bodies are formed of at least one material selected from the group consisting of Ag, Au, Cu, Fe, Co, Ni, W, In, Zn, Cr, Ti, and Pt.
(4) The light-emitting device further includes a defect portion among the metal bodies in the dielectric layer selectively, and the defect portion lacks part of the metal bodies.
(5) The defect portion includes cavities.
(6) The light-emitting device further includes dielectric bodies among the metal bodies in the dielectric layer selectively, and the dielectric bodies are different from the dielectric layer in refractive index.
(7) The photonic crystal structure includes dielectric layers and metal layers stacked alternately with the dielectric layers.
(8) Each of the dielectric layers and each of the metal layers are provided with a one-dimensional periodic structure.
(9) Each of the dielectric layers and each of the metal layers are provided with a two-dimensional periodic structure.
(10) The dielectric layers are formed of at least one material selected from the group consisting of TiO
2
, SiO
2
, Al
2
O
3
, Si, and Zro
2
, and the metal layers are formed of at least one material selected from the group consisting of Ag, Au, Cu, Fe, Co, Ni, W, In, Zn, Cr, Ti, and Pt.
(11) The light-emitting element is formed of at least one material selected from a group consisting of W, Si, SiC, GaN, AlN, graphite, diamond, and amorphous carbon.
(12) The first filament is provided with first holes, and the first holes are arranged periodically along a direction in which the first filament extends and corresponding to the photo
Flynn Nathan J.
Mondt Johannes P
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