Hair cutting device

A hair cutting device for cutting hair on a surface having a surface refractive index, the hair cutting device comprising:

• a light source configured to generate laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in the hair;
• and
• a cutter having an optical waveguide coupled to the light source to receive the laser light,
• wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting the hair, and
• wherein, at least at the one or more specific wavelengths, the cutting face of the optical waveguide has a waveguide refractive index which is higher than the surface refractive index to avoid coupling into the surface when the surface contacts the optical waveguide, and
• wherein the waveguide refractive index of the optical waveguide changes with increasing distance from an optical axis of the optical waveguide, the optical axis being along a center of the optical waveguide.

A method of forming a hair cutting device for cutting hair on a surface having a surface refractive index, the method comprising acts of:

• providing a light source configured to generate laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in the hair;
• and
• providing a cutter having an optical waveguide coupled to the light source to receive the laser light,
• wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting the hair, and
• wherein, at least at the one or more specific wavelengths, the cutting face of the optical waveguide has a waveguide refractive index which is higher than the surface refractive index to avoid coupling into the surface when the surface contacts the optical waveguide, and
• wherein the waveguide refractive index of the optical waveguide changes with increasing distance from an optical axis of the optical waveguide, the optical axis being along a center of the optical waveguide.