Patent Number: 
Section: claims

1. An optical etching device, comprising:an incident light for providing exposing energy;an optical head for converting said incident light to a subwavelength-scale light beam, said optical head including:a transparent substrate;a thin film having a first surface attached to said transparent substrate, a second surface opposite to said first surface, an inner surrounding wall extending from said first surface to said second surface and a passage with a subwavelength aperture confined by said inner surrounding wall, said passage enabling said incident light propagating from said transparent substrate toward said thin film to generate surface waves on said inner surrounding wall; anda surface subwavelength structure formed on said second surface of said thin film for modulating the generated surface waves; anda photoresist layer for absorbing energy of the subwavelength-scale light beam of said optical head to perform a lithographic process. 2. The optical etching device of claim 1, wherein further comprising a translational stage to change the relative position between said optical head and said photoresist layer so as to etch patterns. 3. The optical etching device of claim 1, wherein said incident light is generated by a laser source. 4. The optical etching device of claim 1, wherein the structure depth of said surface subwavelength structure of said optical head is larger than 0.025 times the wavelength of said incident light. 5. The optical etching device of claim 1, wherein said surface subwavelength structure is a periodic structure. 6. The optical etching device of claim 1, wherein said surface subwavelength structure of said optical head is a periodic structure with a period ranging between 0.35 times and 0.8 times the wavelength of said incident light. 7. The optical etching device of claim 1, wherein said surface subwavelength structure of said optical head is a periodic structure with a period ranging from 0.45 times to 0.7 times the wavelength of said incident light to provide a good subwavelength light beam. 8. The optical etching device of claim 1, wherein said surface subwavelength structure of said optical head is a grating structure. 9. The optical etching device of claim 1, wherein said thin film of said optical head is formed of a material with a relative dielectric constant ranging from −4.5 to −6.5. 10. The optical etching device of claim 1, wherein said thin film of said optical head is formed of a material with a relative dielectric constant ranging from −15 to −32. 11. The optical etching device of claim 1, wherein said surface subwavelength structure is formed of a material with a relative dielectric constant ranging from −4.5 to 6.5. 12. The optical etching device of claim 1, wherein said surface subwavelength structure is formed of a material with a relative dielectric constant ranging from −15 to −32. 13. The optical etching device of claim 1, wherein said surface subwavelength structure is formed of a material with a relative dielectric constant ranging from −2.5 to −3.3. 14. The optical etching device of claim 1, wherein said surface subwavelength structure is formed of a material with a relative dielectric constant ranging from −4.8 to −6.5. 15. The optical etching device of claim 1, wherein said surface subwavelength structure is formed of a material with a relative dielectric constant ranging from 8.8 to 9.2.