Comparison of supercontinuum generation in bulk sapphire and femtosecond-laser-inscribed waveguides

We reported that depressed cladding waveguides were successfully fabricated in the sapphire crystal using a femtosecond laser. In waveguides and bulk sapphire, experimental studies and comparisons of supercontinuum generation (SCG) have been carried out. The integrated intensity ratio of the supercontinuum generated by the waveguide with a radius of 36 mu m(WGI) to bulk sapphire reaches 2.56:1(400 nm-1028 nm) when the input pulse energy of 7.3 mu J. The SCG threshold in the waveguide with a radius of 24 mu m(WGII) is about 15 % lower than bulk sapphire. The results reveal that when compared to bulk sapphire, the SC's generation efficiency improves while the threshold in the waveguide decreases. Our work proves that femtosecond laser fabricated waveguide can enhance the light-matter interaction and has great potential for the SCG.

Automated summary

We successfully fabricated depressed cladding waveguides in sapphire crystal using a femtosecond laser. Experimental studies and comparisons of supercontinuum generation (SCG) were conducted in waveguides and bulk sapphire. The results show that the SCG efficiency improves and the threshold decreases in the waveguide compared to bulk sapphire, indicating the great potential of femtosecond laser fabricated waveguides for SCG.