Optical path design and evaluation in Tm³ doped glass channel waveguide for S-band amplification

To achieve high-gain S-band waveguide amplifiers and promote the practicality of integrated signal amplification devices, bent waveguide structures based on Tm³ doped germanate glass substrate have been designed. Using simulated-bend method, the optimal radius for the curved structure is offered to be 1.90 cm with a loss coefficient of 0.04 dB/cm, as the substrate size is minimally schemed. For the folded-spiral waveguide, the internal gain at 1482 nm is derived to be 13.01 dB, which is higher than the values of 8.21 and 4.22 dB in the U- and S-bend waveguides, respectively, and nearly three times higher than that of the straight one. Simulation results indicate that the optical path design is attractive in realizing the high gain of Tm³ doped germanate glass channel waveguides for practical S-band amplification.