Abstract

Single-mode fiber optic couplers have been produced using ion exchange in glass by a process similar to that of multimode devices that previously were described.^1,2 Photolithography is used to transfer an optical circuit design onto masked substrates that then are submitted to a two-step ion exchange process. Thallium is used as the dopant ion. Figure 1 illustrates the depth to which single-mode waveguides have been buried in the substrate. The center of the waveguide core is buried to 30 μm beneath the glass surface while retaining desired guide performance in other respects (cutoff wavelength, mode field diameter, etc.). At a depth of 20-30 μm, propagation characteristics of the device are protected from the surrounding environment and surface scattering losses are avoided.

© 1990 Optical Society of America