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The imaging characteristics of volume holographic imaging elements (VHIEs) are evaluated numerically and experimentally. To evaluate the imaging characteristics of a VHIE, a volume holographic imaging simulator between one-dimensional regions is fabricated. In the simulator, the propagated light in free space and the diffracted light at the VHIE are calculated by numerical Fresnel propagation and Kogelnik's coupled wave theory, respectively. The imaging characteristics of VHIEs for imaging between point sources and between one-dimensional regions are evaluated. Furthermore, we numerically and experimentally investigate the influences of Bragg-mismatched light on imaging characteristics along the direction of the optical axis of a VHIE.

Optical switching elements using controllable defect modes in one-dimensional photonic crystals are proposed. The transmittance in a defect mode is markedly changed by modifying the local structure of the photonic crystals. Such modification is implemented by micro electro mechanical systems (MEMS) or optical manipulation. We present two methods of changing the transmittance in the defect mode. The spectral transmittance and peak wavelength in the defect mode, and the extinction ratio between on and off states are numerically analyzed using plane waves and Gaussian beams. Numerical results show that the extinction ratio is about 40 dB in 43 layers of SiO2 and air with a thickness of 6.8 µm.

In a three-dimensional (3D) eye-gaze detection system with an integrated volume holographic imaging element (VHIE) and two image sensors, human eye gaze is detected by analyzing both the reflected images of two eyes of a human and the transmitted images that the human is watching. To make the detection of the reflected images of the eyes more effective, a noise filter for removing the background noise is fabricated and is then attached to the integrated VHIE. The results obtained by the noise reduction technique are presented.