Patent ID: 8515224

Claim:
A method for writing a Bragg grating in a rare-earth doped glass optical waveguide, the Bragg grating reflecting light at a target wavelength, said method comprising: a) generating ultrafast optical pulses having a writing wavelength in the range of 300 nm to 700 nm and an intensity sufficient to induce a change of refractive index in the rare-earth doped glass waveguide through material densification; b) diffracting the optical pulses using a phase mask to generate an interference pattern having a pitch providing a fundamental Bragg resonance corresponding to said target wavelength; c) impinging the interference pattern on a region of the rare-earth doped glass waveguide to write the same therein and define said Bragg grating; and d) heating the region of the waveguide containing the Bragg grating to a temperature above a threshold of about 350° C. for a predetermined heating period sufficient to substantially eliminate photodarkening effects in said waveguide.