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ABSTRACT: In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results showed a beam steering angle of 10 degree for 30 nm wavelength variation.
Journal of Nanoscience and Nanotechnology 03/2010; 10(3):1650-5. · 1.56 Impact Factor
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ABSTRACT: An electrooptically-active 80-nm-slot silicon photonic crystal waveguide is experimentally demonstrated. The index perturbation enhancement of 30 times is demonstrated in a Mach-Zehnder interferometer configuration. The second enhancement factor is the energy confinement within the slot region of the photonic crystal waveguide. The combined effect provides good potential for sensor applications.
IEEE Journal of Selected Topics in Quantum Electronics 11/2009; · 3.78 Impact Factor
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ABSTRACT: A high-speed compact silicon modulator based on the lateral capacitor configuration is experimentally demonstrated with low-power consumption and 3 dB modulation depth. The capacitor layout is introduced to scale down the total modulator capacitance to 30x10(-15) F, which effectively reduces the rf power consumption to 0.54 pJ/bit. Exploiting the slow group velocity of light in the slot photonic crystal waveguides, the device reported herein exhibits higher modulation efficiency than conventional capacitor modulator and provides a V(pi)L figure of merit of 0.18 Vcm at the wavelength of 1548 nm.
Optics Letters 04/2009; 34(5):602-4. · 3.40 Impact Factor
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ABSTRACT: In this paper, we reported the fabrication of 2-D square lattice photonic crystals structures targeted at beam steering application using double exposure holographic interference method. Computer simulation gives the electric field distribution patterns and SEM images show the developed photonic crystals on the glass substrate.
IEEE/LEOS Winter Topicals Meeting Series, 2009; 02/2009
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ABSTRACT: In this paper, the physical mechanism governing the optical modulation in a p-i-n-diode-embedded photonic crystal (PC) silicon Mach-Zehnder interferometer modulator is examined. Optical simulations have been performed to study how the slow group velocity of the photonic crystal waveguides enables a significant reduction of device size. The theoretical speed limitation in a PC-based silicon modulator is also explored. The 2-D semiconductor device simulator MEDICI has been employed to analyze the transient behavior of the p-i-n-diode-embedded silicon modulator. Electrical simulations have revealed a significant improvement in modulation speed upon the enhancement of current density in a downscaled PC device. High-speed optical modulation at 1 Gmiddots<sup>-1</sup> has been experimentally demonstrated. The performance degradation in optical modulation at the low-frequency operation region attributed to the thermooptic effect is identified and discussed. Simulations have also revealed that the modulation speed of our device can be improved up to 10 GHz by further reducing the device dimensions with little penalty of the increased optical loss.
IEEE Journal of Selected Topics in Quantum Electronics 08/2008; · 3.78 Impact Factor
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ABSTRACT: A MOS-capacitor-based silicon photonic crystal modulation device is proposed to achieve active transmission control with ultra-low gate capacitance and simplified fabrication processes. Optical and electrical simulation results confirm the enhanced modulation efficiency.
Group IV Photonics, 2007 4th IEEE International Conference on; 10/2007
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ABSTRACT: A rigorous theory for solving general 3-D photonic crystal refraction problem is developed. The power flow direction and transmission intensity of each mode refracted at a periodic surface are rigorously analyzed and determined from matrix equations. We further illustrate how to apply our method to design a low-index-contrast 3-D superprism structure that exhibits efficient transmission over a wide angular scanning range at wavelengths near 1550 nm.
Journal of Lightwave Technology 10/2007; 25(9):2469-2474. · 2.78 Impact Factor
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ABSTRACT: The authors experimentally demonstrate a slot photonic crystal structure for guiding light in a sub- 100- nm -wide low-index region. A multimode interference-based coupling structure is introduced to couple light into such a narrow slot photonic crystal waveguide. A coupler of 1.26 μ m long enhances the coupling efficiency by 20 dB for the quasi-transverse-electric mode over 35 nm optical bandwidth centered at 1562 nm . The measured transmission spectra are in good agreement with the simulated band diagram.
Applied Physics Letters 09/2007; · 3.84 Impact Factor
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ABSTRACT: Ultracompact thermooptically tuned photonic crystal waveguide (PCW) silicon-on-insulator Mach-Zehnder interferometers (MZIs) have been proposed and fabricated. A novel thermal design was employed to improve the device switching performance. Both steady-state and transient thermal analyses were performed to evaluate the thermal performance of the thermooptic MZIs. A switching time less than 20 mus has been experimentally achieved, which clearly demonstrated the speed advantage using the new heating approach. The active length of the PCW-based MZIs was 80 mum, nearly one order of magnitude shorter than the conventional silicon waveguide-based MZIs. A maximum modulation depth of 84% for a switching power of 78 mW was obtained at a wavelength of 1548 nm
IEEE Photonics Technology Letters 04/2007; · 2.19 Impact Factor
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ABSTRACT: A polygonal prism based holographic fabrication method has been demonstrated for a three-dimensional face-centered-cubic-type submicron polymer photonic crystal using both positive and negative photoresists. Special fabrication treatments have been introduced to ensure the survivability of the fabricated large area (∼1 cm <sup>2</sup>) nanostructures. Scanning electron microscopy and diffraction results proved the good uniformity of the fabricated structures. With the proper design of the refraction prism the authors have achieved the required band gap for S+C bands (1460–1565 nm ) in the [111] direction. The transmission and reflection spectra obtained by Fourier transform infrared spectroscopy are in good agreement with simulated band structure.
Applied Physics Letters 03/2007; · 3.84 Impact Factor
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ABSTRACT: A 15-Gb/s bit-interleaved optical backplane bus interconnection is experimentally demonstrated in a three-board system based on optical backplane using volume photopolymer holograms. During upstream data transferring, bit pulses from each daughter board are superposed to form an interleaved sequence while for downstream data transferring, the data broadcast from the central board are time-division demultiplexed locally at each daughter board, and only the destined bits are stored respectively. In this way, slow electronic chips can be coordinated to generate a high aggregated bandwidth to relieve wiring congestion. Both nonreturn-to-zero and return-to-zero signaling modes based on vertical-cavity surface-emitting laser sources and pulse lasers are independently employed to implement 2.5- and 15-Gb/s operations. This optical bus architecture also provides a secure and reliable data storage method at 850 nm with a bit-error rate better than 10<sup>-12 </sup>
IEEE Photonics Technology Letters 11/2006; · 2.19 Impact Factor
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ABSTRACT: Chromatic dispersion of highly dispersive photonic crystal fibers (PCFs) is theoretically simulated and experimentally measured as a function of temperature. We have theoretically confirmed that PCFs designed at highly dispersive region show stronger temperature dependence than conventional telecommunication fibers and dispersion compensation fibers due to phase matching wavelength shift and large dispersion slope. For a fabricated highly dispersive PCF, the variation of the dispersion is measured to be around +0.28%/° C from 21 to 80 ° C , and around +0.21%/° C from 21 to 50 ° C at an optical wavelength around 1550 nm .
Applied Physics Letters 02/2006; · 3.84 Impact Factor
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ABSTRACT: An ultracompact silicon electro-optic modulator was experimentally demonstrated based on silicon photonic crystal (PhC) waveguides for the first time to our knowledge. Modulation operation was demonstrated by carrier injection into an 80 μ m -long silicon PhC waveguide of a Mach-Zehnder interferometer (MZI) structure. The π phase shift driving current, I<sub>π</sub> , across the active region is as low as 0.15 mA , which is equivalent to a V<sub>π</sub> of 7.5 mV when a 50 Ω impedance-matched structure is applied. The modulation depth is 92% operating at 1567 nm .
Applied Physics Letters 12/2005; · 3.84 Impact Factor
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ABSTRACT: Miniaturized, delay-enhanced, continuous true-time delay modules based on the holographic dispersion have been designed, fabricated, and demonstrated to provide squint-free beam steering for K-, Ku-, and X-band (8-26.5 GHz) phased-array antenna systems. A novel symmetric structure is employed in the system to achieve large delays and high packaging density. The delay modules operating in the 1550-nm region provide 130 ps of continuously tunable time delay. Far-field radiation patterns measured at 18 and 22 GHz have experimentally verified the K-band beam-scanning coverage from -45° to +45°.
IEEE Photonics Technology Letters 11/2005; · 2.19 Impact Factor
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ABSTRACT: A phase-compensation scheme is proposed and demonstrated to overcome the intrinsic tradeoff between the dispersion and the bandwidth of a volume grating. Its application to a volume grating-based dense wavelength-division multiplexing (DWDM) device is explored. A DWDM device is fabricated by using a 45°/82° configuration. To achieve phase compensation of the Bragg condition, a wavelength-dependent incident angle for a dispersion-enhanced holographic grating at 82° is generated through a prestaged volume hologram at 45°. The 3 dB dispersion bandwidth is increased five times by using such a device configuration. A 21-channel DWDM device centered at 1555 nm with 200 GHz spacing is demonstrated within its 3 dB bandwidth.
Applied Physics Letters 04/2005; 86(18):181103-181103-3. · 3.84 Impact Factor
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ABSTRACT: In this paper, a miniaturized continuously tunable optical true-time-delay module has been designed, fabricated and evaluated for integrating into a X-band 4X4 2-D phased array antenna system. A novel symmetric structure is introduced to keep the output beam position fixed and avoid using a set of large collimators. This new structure is compact and easy to package while providing doubled delay time. Therefore, this module can easily scale up for large arrays due to its compressive structure.
Biophotonics/Optical Interconnects and VLSI Photonics/WBM Microcavities, 2004 Digest of the LEOS Summer Topical Meetings; 07/2004
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ABSTRACT: We review the basic principles, structural designs, and electrical characteristics of photonic crystal waveguide modulators based on slow light Mach-Zehnder interferometers. A number of structural and electrical configurations of photonic crystal waveguide modulators are discussed. In addition to the advantages associated with the slow group velocity, photonic crystal waveguide modulators are found to exhibit other structural and optoelectronic merits for high speed modulation. We also briefly review past work on silicon modulators and present certain speed scaling of silicon modulators. The scaling is governed by certain intrinsic optoelectronic properties of silicon and fundamental nature of light, and plays a significant role in determining the minimum ac current density and power of silicon modulators as demonstrated in some recent experiments.
Solid-State Electronics.
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ABSTRACT: In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results were also reported.
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ABSTRACT: We presented a soft lithography technique of fabricating polymer photonic crystal superprism structures using elastomeric polydimethylsiloxane templates. Dense two-dimensional photonic crystal superprism structures with feature sizes of 150– 500 nm and aspect ratios of up to 1.25 were replicated. Large field size and easy fabrication are two major advantages when compared with other imprint technology. Atomic force microscopy images showed that the molded structures had high fidelity to the masters. Less than 3% reduction of the depth in the molded structures was achieved with respect to the master. The increase of the surface roughness from the master to the molded structures is minimal. The issue of pattern collapse during pattern transfer of submicron structures was analyzed against the pattern dimensions and aspect ratios; and the experimental results were found in agreement with a prior theory. We also experimentally demonstrated the superprism effect in two-dimensional photonic crystal structure at near-infrared wavelength. The propagation beam changed 39° in the photonic crystal with respect to the input wavelength varying from 1546 to 1572 nm. Such an effective, low cost, and high throughput soft lithography technique could find wide use in making photonic crystal based nanostructures. © 2007 American Institute of Physics.
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ABSTRACT: Photonic crystal based superprism offers a new way to design new optical components for beam steering and DWDM application. 3D photonic crystals are especially attractive as they could offer more control of the light beam based on the needs. A polygonal prism based holographic fabrication method has been demonstrated for a three-dimensional face-centered-cubic (FCC)-type submicron polymer photonic crystal using SU8 as the photo-sensitive material. Therefore antivibration equipment and complicated optical alignment system are not needed and the requirement for the coherence of the laser source is relaxed compared with the traditional holographic setup. By changing the top-cut prism structure, the polarization of the laser beam, the exposure and development conditions we can achieve different kinds of triclinic or orthorhombic photonic crystals on demand. Special fabrication treatments have been introduced to ensure the survivability of the fabricated large area (cm 2) nano-structures. Scanning electron microscopy and diffraction results proved the good uniformity of the fabricated structures. With the proper design of the refraction prism we have achieved a partial bandgap for S+C band (1460-1565nm) in the [111] direction. The transmission and reflection spectra obtained by Fourier transform infrared spectroscopy (FTIR) are in good agreement with simulated band structure. The superprism effects around 1550nm wavelength for the fabricated 3D polymer photonic crystal have been theoretically calculated and such effects can be used for beam steering purpose.
