Optical loss measurements in femtosecond laser written waveguides in glass

Abstract:

The optical loss is an important parameter for waveguides used in integrated optics. We measured the optical loss in waveguides written in silicate glass slides with high repetition-rate (MHz) femtosecond laser pulses. The average transmission loss of straight waveguides is about 0.3 dB/mm at a wavelength of 633 nm and 0.05 dB/mm at a wavelength of 1.55 m. The loss is not polarization dependent and the waveguides allow a minimum bending radius of 36 mm without additional loss. The average numerical aperture (NA) of the waveguides is 0.065 at a wavelength of 633 nm and 0.045 at a wavelength of 1.55 m. In straight waveguides more than 90% of the transmission loss is due to scattering.