Patent Number: 
Section: claims

1. A terahertz wave generator, comprising:a spherical body, an inside of which is hollow space, the spherical body having an inner surface coated with metal or made of metal; andany one of a focusing lens, installed in a predetermined portion of the spherical body and interposed between an outer surface and the hollow space of the spherical body, and an opening of a predetermined size formed after a predetermined portion of the spherical body is cut out,wherein light signals incident through the focusing lens or the opening are focused and collimated in the hollow space of the spherical body and are reflected from an inner surface of the spherical body, so that a plurality of air plasmas is generated, and a plurality of terahertz waves, generated when the air plasmas undergo a reaction, are superposed on one another, and thus high-power terahertz waves are generated. 2. The terahertz wave generator according to claim 1, wherein the metal is aluminum or one of any metal material capable of reflecting light signals ranging from visible rays to terahertz waves. 3. The terahertz wave generator according to claim 1, wherein a number of air plasmas generated in the hollow space of the spherical body is controlled by adjusting incidence angles of the light signals that are incident through the focusing lens or the opening. 4. The terahertz wave generator according to claim 1, wherein:the light signals are two light signals having a frequency of ω and a frequency of 2ω; andthe light signal having the frequency of 2ω is generated by Second Harmonic Generation (SHG) occurring when femtosecond laser light having a frequency of ω is applied to a beta-BaB2O4 (BBO) or a lithium triborate (LiB3O5 or LBO) crystal. 5. A method of generating high-power terahertz waves using a terahertz wave generator in which an inside of a spherical body is hollow space, an inner surface of the spherical body is made of metal or coated with metal, and a focusing lens or an opening is formed in a predetermined portion of the spherical body, the method comprising:allowing light signals to be incident through the focusing lens or the opening;focusing or collimating the incident light signals in the hollow space of the spherical body;generating a first air plasma from the focused light signals;generating first terahertz waves when the first air plasma undergoes a reaction;collimating the light signals in the hollow space of the spherical body;reflecting the light signals from the inner surface of the spherical body;focusing the reflected light signals in the hollow space of the spherical body;generating a second air plasma from the focused light signals; andgenerating second terahertz waves when the second air plasma undergoes a reaction, and superposing the second terahertz waves on the first terahertz waves. 6. The method according to claim 5, further comprising, after the first terahertz waves and the second terahertz waves have been superposed:collimating the light signals in the hollow space of the spherical body;reflecting the light signals from the inner surface of the spherical body;focusing the reflected light signals in the hollow space of the spherical body;generating a third air plasma from the focused light signals; andgenerating third terahertz waves when the third air plasma undergoes a reaction, and superposing the third terahertz waves on the terahertz waves in which the first and second terahertz waves are superposed on each other. 7. The method according to claim 6, further comprising:repeating collimation and focusing of the light signals in the hollow space of the spherical body, and reflection of the light signals from the inner surface of the spherical body, generating an N-th air plasma, generating N-th terahertz waves when the N-th air plasma undergoes a reaction, superposing the N-th terahertz waves on resulting terahertz waves in which terahertz waves which have been generated up to now are superposed on one another, and outputting finally superposed terahertz waves to the focusing lens or the opening. 8. The method according to claim 7, wherein a number of air plasmas generated in the hollow space of the spherical body is controlled by adjusting incidence angles of the light signals that are incident through the focusing lens or the opening. 9. The method according to claim 5, wherein:the light signals are two light signals having a frequency of ω and a frequency of 2ω; andthe light signal having the frequency of 2ω is generated by Second Harmonic Generation (SHG) occurring when femtosecond laser light having a frequency of ω is applied to a beta-BaB2O4 (BBO) or a lithium triborate (LiB3O5 or LBO) crystal. 10. The method according to claim 6, wherein:the light signals are two light signals having a frequency of ω and a frequency of 2ω; andthe light signal having the frequency of 2ω is generated by Second Harmonic Generation (SHG) occurring when femtosecond laser light having a frequency of ω is applied to a beta-BaB2O4 (BBO) or a lithium triborate (LiB3O5 or LBO) crystal. 11. The method according to claim 7, wherein:the light signals are two light signals having a frequency of ω and a frequency of 2ω; andthe light signal having the frequency of 2ω is generated by Second Harmonic Generation (SHG) occurring when femtosecond laser light having a frequency of ω is applied to a beta-BaB2O4 (BBO) or a lithium triborate (LiB3O5 or LBO) crystal. 12. The method according to claim 8, wherein:the light signals are two light signals having a frequency of ω and a frequency of 2ω; andthe light signal having the frequency of 2ω is generated by Second Harmonic Generation (SHG) occurring when femtosecond laser light having a frequency of ω is applied to a beta-BaB2O4 (BBO) or a lithium triborate (LiB3O5 or LBO) crystal.