Microstructuring optical wave guide devices with femtosecond optical pulses

A method for creating an optical waveguiding device from an elongated generally annular optical fiber made of glass material and having at least one core and at least one cladding by creating a zone of permanently altered refractive index characteristics in the optical fiber, using focused beams generated by at least two pulsed laser light sources, each having:

• (i) a wavelength greater than the absorption edge of the glass material;
• (ii) a pulse width of less than 1 picosecond, and a pulse energy of between 1 nanojoule and 1 millijoule;
• and
• (iii) capable of achieving a peak pulse intensity within a defined focal region;
• comprising the steps of:
• (a) aligning each said laser beam focal region with a defined target region within the optical fiber, said target region extending through the core and at least partially through the cladding of the optical fiber, at an acute angle to a longitudinal axis thereof;
• (b) providing relative movement between said optical fiber and said beams such that said laser beam focal regions sweep along said target region;
• and
• (c) operating said laser light sources with the combined peak pulse intensity thereof and a repetition rate thereof selected to accumulate heat and to soften the glass material within the target region and to thereby induce permanent refractive index changes in the optical fiber within the target region;
• said optical waveguiding device exhibiting controlled polarization sensitivity.

A method for creating an optical waveguiding device from an elongated generally annular optical fiber made of a glass material and having at least one core and at least one cladding by creating a zone of permanently altered refractive index characteristics in the optical fiber, using focused beams generated by at least two pulsed laser light sources, each having:

• (i) a wavelength greater than the absorption edge of the glass material;
• (ii) a pulse width of less than 1 picosecond, and a pulse energy of between 1 nanojoule and 1 millijoule;
• and
• (iii) capable of achieving a peak pulse intensity within a defined focal region;
• comprising the steps of:
• (a) combining said laser beam focal regions to create a single beam focal region;
• (b) aligning said single focal region with a defined target region within the optical fiber, said target region extending through the core and at least partially through the cladding of the optical fiber, at an acute angle to a longitudinal axis thereof;
• (c) providing relative movement between said optical fiber and said beams such that said laser beam focal regions sweep along said target region;
• and
• (d) operating said laser light sources with the combined peak pulse intensity thereof and a repetition rate thereof selected to accumulate heat and to soften the glass material within the target region and to thereby induce permanent refractive index changes in the optical fiber within the target region;
• said optical waveguiding device exhibiting controlled polarization sensitivity.

A method for creating an optical waveguiding device from an elongated generally annular optical fiber made of glass material and having at least one core and at least one cladding by creating a zone of permanently altered refractive index characteristics in the optical fiber, using a focused beam which is generated by a pulsed laser light source having:

• (i) a wavelength greater than the absorption edge of the glass material;
• (ii) a pulse width of less than 1 picosecond, and a pulse energy of between 1 nanojoule and 1 millijoule;
• and
• (iii) capable of achieving a peak pulse intensity within a defined focal region;
• comprising the steps of:
• (a) applying mechanical stress to said optical fiber;
• (b) aligning said laser beam focal region with a defined target region within the optical fiber;
• (c) operating said laser light source with the peak pulse intensity thereof and a repetition rate thereof selected to accumulate heat and to soften the glass material at the target region and to thereby induce permanent refractive index changes in the optical fiber at the target region;
• and
• (d) removing said mechanical stress once said zone of altered refractive index characteristics has been created.

A method for creating an optical waveguiding device from an elongated generally annular optical fiber made of glass material and having at least one core and at least one cladding by creating a zone of permanently altered refractive index characteristics in the optical fiber, using a focused beam which is generated by a pulsed laser light source having:

• (i) a wavelength greater than the absorption edge of the glass material;
• (ii) a pulse width of less than 1 picosecond, and a pulse energy of between 1 nanojoule and 1 millijoule;
• and
• (iii) capable of achieving a peak pulse intensity within a defined focal region;
• comprising the steps of:
• (a) applying an electric field to said optical fiber;
• (b) aligning said laser beam focal region with a defined target region within the optical fiber;
• (c) operating said laser light source with the peak pulse intensity thereof and a repetition rate thereof selected to accumulate heat and to soften the glass material at the target region and to thereby induce permanent refractive index changes in the optical fiber at the target region;
• and
• (d) removing said electric field once said zone of altered refractive index characteristics has been created.