Optical waveguide fabrication with tailored femtosecond laser pulses

One of the technical issues of waveguide fabrication technique inside transparent materials using femtosecond laser has been an optical loss which may be caused by a nonuniformity of the modified volume. In this paper we report on the optical waveguides fabrication inside fused silica glasses using double pulse femtosecond lasers to solve this issue. We investigate writing conditions of optical waveguides with adjusting pulse intervals and relative fluence of the double pulses. The pulse separation time of the double pulses is varied from 500 fs to 200 ps. The better optical property of the optical waveguides under the conditions that the first pulse energy and the second subsequent pulse energy of the double pulse mode are 30 nJ and 160 nJ, respectively and pulse separation time is 3 ps. This optical loss is smaller than that of the waveguides fabricated using a single pulse femtosecond laser.