K. Rastani

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Two-dimensional arrays of mutually coherent optical beams are needed in holographic interconnections for both recording and reading gratings. We analyze the use and limitations of binary phase Fresnel lenses to generate beams for these applications. Two known techniques of ion beam milling and thin film deposition are compared to fabricate such lens arrays(More)
An active-fiber star coupler that uses arrays of N x N microlenses and liquid-crystal modulators is presented. A simplified implementation of this device uses an 8 x 8 array of Fresnel microlenses fan out an incident beam into 64 focused spots (an 18 dB fan-out loss); on-off capability (270:1 extinction ratio) at each element is provided by liquid-crystal(More)
We describe the properties and construction of a polarization-independent Fresnel lens array using nematic liquid crystals in which the diffraction efficiency of lenses can be electrically controlled. A novel structure is used such that the principal axis of the liquid crystals in two adjacent zones of each Fresnel lens are orthogonal. This makes the device(More)
Storage capacity of a volume is derived based on the space-bandwidth products of angularly multiplexedholograms and by considering their diffraction efficiency and cross-talk limitations. An erasable medium of Fe:LiNbO(3) (10MM × 1mm × 2mm) is simulated thatyieldsacapacity of ˜ 26 Gbits for 95 holograms, each with an efficiency of ~ 10(-4), for a total of ~(More)
We report a technique of integrating planar Fresnel microlenses with InGaAs/GaAs-based vertical-cavity surfacee-mitting laser arrays by selectively ion-beam milling the substrate. Depending on the application, one can focus, collimate, and bend the individual laser beams using such microlenses. An example is presented where a 32 x 32 array of microlenses,(More)
Evaluation of the paranasal sinuses and nasal cavity in patients with headache and or facial pain must include a thorough medical and social history, with close attention to the pattern and character of the pain, a thorough physical examination that includes a palpation and nasal endoscopy, and imaging studies such as CT scans and Magnetic Resonance(More)
The known problem of grating erasure in photorefractive-based holographic optical interconnects can lead to limitations in the density of the system. This problem is analyzed for an architecture that uses spatially multiplexed beams (to eliminate cross erasure) and angularly multiplexed input beams to record multiplexed gratings in a bismuth silicon oxide(More)
The use of diffraction gratings to trap optical beams in substrates for optical interconnect applications has been proposed by many. We analyze the alignment and fabrication tolerances of such gratings to make them viable for such applications. The use of chirped circular gratings is proposed as a means of compensating for transverse-optical beam(More)
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