Optical Filters Based On Waveguide Grating Structures

Waveguided grating structures (WGS) are a kind of narrow-band optical filters, which are composed of a substrate, a waveguide layer, and grating structures. The light is firstly diffracted by the grating, which excites the propagation mode in the waveguide. Further diffraction of the waveguide propagation mode by the grating produces multiple beams that propagate parallel to that direct transmission beam through the WGS. Destructive interference between the diffracted beams and the directly transmitted beam give rise to a narrow-band optical response in the extinction spectrum. WGS can be used to construct waveguided metallic photonic crystals (WMPC), which show novel optical properties due to strong coupling between the waveguide resonance mode and the particle plasmon resonance. The optical devices based on WGS and WMPC can be widely used in biosensors, optical filters and optical switches.This thesis demonstrates the fabrication of waveguide ternary gratings and the WGS based on large-period grating structures. After systematic investigation on different kinds of WGS devices, we find that,(i) Some abnormal phenomena, such as enhanced transmission, can be observed when the grating period is much larger than the wavelength. Furthermore, the resonant mode can be tuned by changing the angle of incident light.(ii) Waveguide ternary gratings have three sets of narrow-band waveguide resonance modes, which can be tuned over the whole visible spectral range through changing the incident angle of the light. This has thus introduced multifold structures and multiple functions into an individual WGS device and may enhance the sensitivity of the corresponding optical response to the change of the environmental or structural parameters of the device due to the simultaneous operation of multiple mutually related optical signals.At last, we demonstrate the fabrication and optical properties of WMPC by interference lithography and solution-processible method. The experimental results in this thesis enhance the flexibility of the potential applications of the waveguide grating structures in filters, optical switch, and sensors.