Nonlinear properties of the depressed cladding single mode TeO2-WO3-Bi2O3 channel waveguide fabricated by direct laser writing

Abstract

A large mode area depressed cladding waveguide was inscribed by a femtosecond laser beam in bulk of high purity 70TeO2-22WO3-8Bi2O3 glass. Non-linear propagation of femtosecond pulses in the single mode waveguide with mode field diameter of 12 μm was investigated under input at 1030 nm wavelength. The highest peak value of a Raman-gain coefficient of all the tellurite glasses was measured (1.2x10−9 cm/W). The dispersion of the refractive index was obtained in the range of 1170-2300 nm. Spectrum broadening of up to 160 nm at the −10 dB level was observed under input pulse energy as low as 84 nJ in a 14 mm long waveguide. The spectrum broadening was numerically simulated, and it was found that both the Kerr and the Raman nonlinearities result to comparable contributions to the spectrum transformation.