Silicon Photonics: Fundamentals and Devices

12.6 PHASAR-Based Devices on Different Materials

PHASAR-based devices, in particular AWGs, have been fabricated by using different materials systems that have been introduced in Section 12.1. We discuss in this section the characteristics of the devices grown on different materials systems.

12.6.1 Silica on Silicon

As already mentioned, devices realized with this materials system excessively outnumber the devices grown on other materials. The principal reason lies in the fact that a few large companies as well as several other groups use silica waveguides for their device fabrication [26–29]. All the devices and components discussed in this chapter have been realized using silica on silicon, and the athermal and polarization-insensitive characteristics are also demonstrated. A number of review articles have appeared in the literature describing the basic principles, device fabrication, characteristics, and applications of PHASAR-based devices, and the reader is referred to the articles and the long list of references given therein.

The characteristics of the devices have been discussed. The devices show polarization insensitivity when a half-wavelength polyimide plate is inserted in the guide regions. Furthermore, athermal behavior is ensured by the use of silicone resin in narrow optical grooves created in the arrayed waveguide region. A modified form of the groove to reduce the excess loss due to triangular design, the triangular groove is replaced by arrow-shaped stripes spaced ...