Fabrication of a LP01 to LP02 mode converter embedded in bulk glass using femtosecond direct inscription

In this paper, we demonstrate a fabrication of an integrated mode converter that converts LP01 to LP02 for the C-band. The mode converter was directly inscribed in the bulk of a borosilicate glass using a femtosecond laser. The converter has an insertion loss of less than 1 dB for the entire C-band, suggesting more than 80% conversion efficiency.