A two-step K<sup>+</sup>-Na<sup>+</sup> and Ag<sup>+</sup>-Na<sup>+</sup> ion-exchange technique is introduced to fabricate single-mode channel waveguides in BK7 glass for the telecom-wavelength region. The dependencies of insertion loss, polarization-dependent loss (PDL), and bending loss of curved waveguides on channel width, diffusion time, and annealing time are investigated. Results show that postannealing is a required process for improving waveguide properties and an optimal annealing time exists. Although relatively narrow mask openings are used in most one-step ion-exchange processes, a wider channel width, to as wide as 10 μm, is preferred for this two-step method. The minimum coupling loss to/from single-mode fiber and the propagation loss is found to be 0.4 dB and 0.3 dB/cm, respectively. For 5-cm-long waveguides the PDL is less than 0.1 dB. For the S-bend structure the cosine curve exhibits apparently a lower bending loss than the double-arc curve.
© 2002 Optical Society of America
Jizuo Zou, Feng Zhao, and Ray T. Chen, "Two-step K+-Na+ and Ag+-Na+ ion-exchanged glass waveguides for C-band applications," Appl. Opt. 41, 7620-7626 (2002)