| CPC H04B 10/503 (2013.01) [H04B 10/116 (2013.01); H04B 10/516 (2013.01)] | 12 Claims |
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1. A transmission device configured to transmit a visible light signal to a receiving device, comprising:
a laser light source configured to emit visible light, the visible light is red light, green light, or blue light each having a different wavelength;
an optical modulator configured to change intensity of the visible light and generate a visible light signal corresponding to the red light, green light, or blue light; and
an electrical signal generation element configured to receive information data to be transmitted, and output the information data to the optical modulator,
wherein the optical modulator has an optical waveguide that serves as a transmission path for the visible light, and an electrode layer that modulates the visible light traveling in the optical waveguide,
the optical waveguide is formed of a material containing lithium niobate,
the optical waveguide has a ridge portion and a flat portion,
a wavelength of the red light is 638 nm,
a wavelength of the green light is 520 nm,
a wavelength of the blue light is 473 nm,
a width of a cross section perpendicular to a transmission direction of the visible light of the ridge portion in the optical waveguide is within a range of 510.4 nm or more and 1182.5 nm or less, and a height of the cross section of the ridge portion is within a range of 510.4 nm or more and 709.5 nm or less,
the electrical signal generation element is configured to change a voltage value Vπ required to phase-modulate the wavelength of light to half-wavelength applied to the electrode layer by the visible light transmitting through the optical waveguide, and
an integrated value Vπ*Li[V*cm] which is a product of the voltage value Vπ and an interaction length Li is 1.79 V*cm when the visible light is the red light, is 1.39 V*cm when the visible light is the green light, and is 1.20 V*cm when the visible light is the blue light.
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