[Show abstract][Hide abstract] ABSTRACT: Resonant filters in waveguides with vertical gratings have been realized on a silicon-on-insulator wafer. Two identical uniformly distributed Bragg reflectors with vertical gratings are separated by a quarter wavelength phase offset. Experimental studies show a broad stopband and a narrow transmission band which shifts with changing substrate temperature that is also illuminated by an external laser pump beam at 514-nm wavelength. Experimental results on a low-frequency thermal modulation using an external light source are also presented
[Show abstract][Hide abstract] ABSTRACT: Transmission resonant filters in a waveguide with vertical gratings have been realized in silicon on insulator wafers. Experimental studies of fabricated devices show a broad stopband of approximately 19 nm in the center of which exists a narrow transmission band of approximately 0.5 nm with a quality factor of approximately 3000. These resonant cavities are useful for laser cavities, switches, modulators, detectors, and tunable filters.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate novel optical devices for controlling vector optical fields in free space, as well as new concept for "free space on a chip" using subwavelength structures etched into a slab waveguide.
[Show abstract][Hide abstract] ABSTRACT: We provide an experimental demonstration of novel form-birefringent computer-generated holograms at wavelengths of 1.55 and 10.6 microm. These novel devices utilize a 2-D array of cells that can be fabricated with a single lithographic step. Each cell contains a subwavelength binary grating whose orientation controls the desired continuous phase profile within the cell.
[Show abstract][Hide abstract] ABSTRACT: We present the optical design of a wavefront coded ultra-thin visible-light camera with 35 mm focal length, 0.12 radian field of view, and 0.7 numerical aperture; folded into a 5 mm total physical track.
[Show abstract][Hide abstract] ABSTRACT: We present a novel configuration for the implementation of subwavelength-based graded-index devices. The proposed concept is based on the etching of one-dimensional subwavelength gratings into a high-index slab waveguide to achieve the desired effective index distribution. A graded-index profile can be achieved by gradually modifying the duty ratio of the grating along the horizontal axis, while the beam is confined in the vertical direction by the slab waveguide. On the basis of this concept, novel graded-index lenses and waveguides are both proposed and characterized numerically by use of finite-difference time-domain and finite-element analysis. The proposed devices can be used for guiding, imaging, optical signal processing, mode matching, coupling, and other applications while offering the intrinsic advantages of on-chip integration such as miniaturization, eliminating the need to align each component separately, and compatibility with standard microfabrication techniques for manufacturability.
Journal of the Optical Society of America A 05/2005; 22(4):724-33. DOI:10.1364/JOSAA.22.000724 · 1.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report the analysis, design, fabrication and experimental characterization of novel subwavelength computer-generated holograms that produce uniform symmetric spot array. We distinguish between a polarization-sensitive and polarization-insensitive far-field reconstruction and show that a linearly polarized incident illumination is required in the former case in order to generate a symmetric reconstruction. The polarization-insensitive case generates a symmetric response independent of the illumination polarization. We show that this response is equivalent to that of a scalar-based computer-generated hologram but with an additional, independent, term that describes the undiffracted zeroth order. These findings simplify the design and optimization of form birefringent computer-generated holograms (F-BCGH) significantly. We present experimental results that verify our analysis and highlight the advantage of these novel elements over scalar-designed elements.