Long-Period Waveguide Gratings

In this paper, we review our research efforts in the development of long-period waveguide gratings (LPWGs). We describe LPWGs fabricated in slab and channel waveguides with polymer and glass by conventional photolithography and reactive ion etching to demonstrate the flexibility of the technology, which leads to many advantages of LPWGs, compared with long-period fiber gratings. In particular, we show that an LPWG can function as a widely tunable filter and it is possible to control its wavelength tunability and polarization sensitivity by controlling the dimensions of the waveguide cladding. We also present an LPWG written in a polymer-clad waveguide by a UV technique. Furthermore, we illustrate experimentally the principle of light coupling among an array of parallel waveguides with identical LPWGs. LPWGs can serve as building blocks for the realization of a wide range of integrated optic devices.