Optical wireless data communication system, and transmitter and receiver used therefor
AssigneeSeiko Epson Corporation
InventorsTakeo Kawase, Takeo Kaneko, Takayuki Kondo, Shojiro Kitamura
Life of this patent
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Abstract
Based on binary transmission data 12, a receiver 11 emits electromagnetic waves 13 with modulated plane of polarization into a free space 16. The data propagates along the free space 16 as the azimuth of the plane of polarization. A receiver 17 accepts the electromagnetic wave 13 with modulated plane of polarization discriminates the data based on the state of the plane of polarization, and outputs the binary received data 18. The data and the clock data are transmitted from a plurality of light-emitting units with different polarization states or wavelengths to omit PLL circuits.
Claims16
An optical wireless data communication system for performing communication by emitting light of a wavelength of 100 μm or less into free space, comprising:
- a transmitter having one or more light sources for emitting two or more types of light with mutually differing optical characteristics, said transmitter comprising an emitting means for individually modulating said two or more types of light based on first transmission data obtained by modulating the transmission data and second transmission data obtained by calculating and converting the transmission data, and emitting two or more mutually differing modulated signal light beams;
- and
- a receiver having one or more light-accepting portions for discriminating and accepting said two or more types of light, said receiver comprising a received data acquiring means for acquiring received data corresponding to said transmission data from the results of the calculation of the modulated signals obtained by accepting said modulated signal light which has propagated along free space.
A transmitter used for an optical wireless data communication system performing communication by emitting light of a wavelength of 100 μm or less into free space, and which comprises one or more light sources for emitting two or more types of light with mutually differing optical characteristics, said light source comprising a vertical cavity surface-emitting semiconductor laser for modulating the direction of polarization of linearly polarized light and a phase plate arranged to transmit the light emitted from said vertical cavity surface-emitting semiconductor laser.
A transmitter used for an optical wireless data communication system performing communication by emitting light of a wavelength of 100 μm or less into free space, and which comprises one or more light sources for emitting two or more types of light with mutually differing optical characteristics, said light source comprising a first semiconductor laser for emitting a first linearly polarized light, a second semiconductor laser for emitting a second linearly polarized light vertical to the plane of polarization of the light emitted from said first semiconductor laser, and a phase plate arranged to transmit the light emitted from said first and second semiconductor lasers.
A receiver used for an optical wireless data communication system performing communication by emitting light of a wavelength of 100 μm or less into free space, comprising:
- a receiving phase plate for converting polarization state of received light into linearly polarized light beams with crossing directions;
- an analyzer for transmitting or reflecting each of the linearly polarized light beams with crossing directions;
- and
- a first and second light-accepting element for photoelectrically converting each of the linearly polarized light beams with crossing directions.
Dependencies are inferred from the claim text.