Polymer/compound semiconductor hybrid micro resonators with very wide free spectral range

In order to keep the Q factor of the micro resonator high, the radius should be many times the operating wavelength. This makes the resonator multi moded and many closely spaced resonances are supported. As a result the free spectral range of the filter is narrow. Although this could be. desirable for some specific applications, in general it is undesirable since it is not possible to filter a specific wavelength over a band of wavelengths. We resolve this difficulty using a hybrid integration technology. For this purpose we use the coupling between a GaAs epilayer removed from its substrate and a polymer channel waveguide as shown . In our previous work we demonstrated the coupling between a GaAs epilayer and a polymer channel waveguide. The structure formed this way is an asymmetric directional coupler, and works as a narrow band filter. In other words coupling in this structure is very wavelength selective.