This PDF file contains the front matter associated with SPIE Proceedings Volume 7936, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Properties of propagating wave in a composite right/left-handed (CRLH) leaky wave antenna rely heavily on the constituent stripe patches. In this paper, we conducted full-wave simulations of structural resonances in a CRLH leaky wave antenna by using finite difference time domain (FDTD) method. E_z field distributions for several lowest-order modes in individual stripe patch were examined, which are named as structural resonances. The Bloch modes in a transmission line were also calculated at high symmetric points in k-space. Study shows that Bloch mode properties are closely related to those in an isolated structure. The mode power densities are well confined below or around the metallic strip patches, which enables tight binding approximation to estimate band properties in the vicinity of Γ point. The calculated dispersion diagram by FDTD tells us many new features, such as accidental degeneracy, a third band arisen from slab mode and the many anti-crossing phenomena. These features are of great importance to analyze the performance of CRLH leaky wave antennae.

Printing technique is a simple and cost effective method to produce electronics. In this work, self-aligned carbon nanotube thin-film transistor based phased shifter has been used to fabricate a 1x4 phased array antenna system on a flexible substrate using a combination of ink-jet printing and stamping techniques. The radiation pattern is measured for different steering angle conditions. Measured and simulated far field radiation patterns are reported, and both data sets agree well with each other. The efficiency the 2-bit 1x4 PAA system is calculated to be 42% including the loss of transmission line, FET switch, and coupling loss of RF probes.

In this paper, we report on progress in the fabrication of a high speed optical phase modulator based on a nonlinear electro-optic (EO) polymer with an in-plane slotline radio frequency (RF) electrode structure. Compared to microstrip, a slotline RF electrode design has several potential advantages such as easy fabrication, high poling efficiency, low V_π, and suppression of current drift. The guest-host nonlinear polymer system AJL49/APC was used in the device. Design, fabrication, and characterization are presented.

Modulators using silicon waveguides with a small (~100 nm) slot in the center of the waveguide filled with an electro-optic polymer can have very low switching voltage. A variety of challenges, including difficulty poling the polymer and difficulty achieving high-speed operation, have so far prevented successful demonstration. Problems poling the polymer may be electrical, such as nonuniform poling fields or too much polymer conductivity compared to the silicon electrodes, or they may be more fundamental. This paper discusses research into one possible improvement in the polymer poling method, which is illumination of the device with an 800-nm-wavelength laser during poling to improve conductivity between the external voltage source and the polymer in the slot.

We numerically investigate high-frequency microwave signal generation utilizing a double injection locking technique. A slave laser (SL) is strongly injected by a master laser 1 (ML1) and a master laser 2 (ML2) optically. Stable locking states are observed when the SL is subject to optical injection by either the ML1 or the ML2 individually. By utilizing the hybrid scheme consists of double optical injections, the advantages of each individual dynamical system are added and enhanced. Comparison of the performances of the spectral width, power fluctuation, and frequency tunability between the signal generated in the double injection locking scheme and the similar period-one (P1) oscillation signal generated in a conventional single injection scheme is studied. A 3-fold linewidth reduction is achieved by utilizing the double injection locking scheme benefitted by the strong phase-locking and high coherence when operating at the stable injection locking state. Moreover, for the double injection locking scheme, a wide continuous tuning range of more than 100 GHz is obtained by adjusting the detuning frequency of the two master lasers. The performances of narrow linewidth, wide tuning range, and frequency continuity show the great advantages of the high-frequency microwave signal generated by the double injection locking technique.

In the microwave domain and among many other advantages, optics represents an elegant solution to increase the quality Q factor in a system. Different types of optical resonators lead to Q factors above 10⁹, and these resonators can be used as an alternative to optical delay lines to set up the frequency in optoelectronic oscillators (OEO). However, microwave-optics is also a complex field, and if the use of optical resonators in high spectral purity frequency generation systems like OEO has been already demonstrated, many aspects of these OEOs are still incompletely understood, especially the contribution to the oscillator phase noise of the different optical and microwave elements used in the oscillator system. In order to improve the phase noise of a fiber ring resonator based OEO, this oscillator has been theoretically studied in term of white frequency noise. In this paper, we present a theoretical study that has lead us to optimize a fiber ring resonator and the experimental phase noise results obtained for an OEO based on an optimized optical resonator. The OEO thermal stability is also investigated in this paper.

Optoelectronic oscillators are ultra-pure microwave generators based on optical energy storage instead of high finesse radio-frequency resonators. We present in this communication a new and compact architecture where the optical energy storage is performed by trapping laser light into the ultra-high Q whispering gallery modes of a millimeter-size disk resonator. As a proof of concept, we demonstrate the generation of a 10.7 GHz microwave with a phase noise of -110 dBrad²/Hz at 100 kHz. We also discuss in detail the potential of this architecture for the generation of microwaves with a frequency ranging from 50 to 200 GHz.

Silicon slot waveguide based Mach Zender interferometric modulators were built with electro-optic (EO) polymers in the slot as the modulated media. In order to enhance the macroscopic electro-optic effect in the polymers the molecules that provide the large polarizability need to be aligned prior to operation to match the direction of the applied modulating field. This aligning process, also called as poling process, is difficult in the slot waveguide modulators due to the unique structure and small dimensionality of the slots in the waveguides. While hybrid silicon-EO polymer modulators have been demonstrated with ultra low drive voltage, the polymer EO activity was low compared to thin film performances. We compared alternatives to enhance the poling field over the electro optic polymer and concluded that the well known surface states in silicon affect the conductivity of silicon significantly when thin silicon is used as poling electrode. A solution to this negative effect was attempted by passivating the surface with a 5 nm thin TiO2 conforming atomic layer deposition over the silicon prior to spin casting and poling the EO polymers. We achieved a factor of 2 enhancement in the polymer's electro optic activity after poling as a result and achieved a low 0.52 V*cm voltage length product in the MZ modulator we built with this technique.

The field of millimeter-wave (MMW) imaging has progressed significantly over the last two decades. The most obvious evidence of this is the widespread use of MMW full-body scanners, now commonly found in airports. The path to this point has been the result of the work of a wide range of experts from many scientific and engineering disciplines. This article represents one perspective of this progress. The development of MMW imagers, and all their associated component technologies, image processing techniques, clever engineering, etc. has been driven by a relatively small number of interesting applications. It has been known for about 70 years that RF energy can be used to "see" through things like clouds and detect, for example, hostile aircraft. As the RF frequency goes up to 35, 100, or 340 GHz, it becomes possible to image through obscurants with much improved resolution. However, as frequency increases, attenuation increases as well, so selecting the right frequency for the application is an important point. The challenge of seeing through obscurants such as fog, smoke and dust drives one towards a MMW imaging solution. Typical applications include guiding aircraft through low visibility conditions, detecting nearby watercraft in the fog, and searching for concealed weapons. So, while these capabilities have been demonstrated numerous times over the years, the practical and affordable implementation of the systems to accomplish these goals is where the real story lies.

Subwavelength metallic structures capable of creating strongly localized electromagnetic field with enormous enhancement under illumination/excitation are designed for direct radio frequency (RF) imaging. Three dimensional finite element method models are applied to investigate the electromagnetic field concentrations of two types of split ring resonators. Under appropriate linearly polarized illumination, a highly confined field located at the gap of the ring resonator is found due to strong scattering resonance. The numerical studies show that field enhancement as high as 6,800 is achieved for a planar D-shaped split ring resonator. The enhancement can be further increased through shrinking the gaps size or the ring width. Crescent shaped split ring resonator is designed for broadband application. It provides an enhanced bandwidth which is 1.15 times of the resonant frequency. The concentrated electromagnetic field facilitates nonlinear processes that find lots of applications. Optimized RF concentrators integrated with electro-optic modulators are demonstrated to directly modulate optical carrier. The combination of RF concentrator and EO modulator could enable a focal plane RF imager array that allows direct RF imaging, and significantly decrease RF aperture size and weight. Additional benefits include enhanced functionality such as inherent polarimetric imaging capability.

Fiber-optic links are attractive for transmitting microwave/millimeter wave signals for applications such as radar, imaging and astronomy. However, current fiber-optic links that employs intensity modulation and direct detection suffer from limited spurious free dynamic range (SFDR). For solution, a new coherent fiber-optic link using linear phase modulation/demodulation has been proposed. The new link should be able to achieve an SFDR two orders of magnitude higher. The key for this link is an Optical Phase Locked Loop (OPLL) linear phase demodulator. In this paper we describe the design and preliminary measurements for the first generation ACP-OPLL photonic integrated circuits.

System requirements, including carrier frequency, transmitted power and antenna gain are presented for a 10 Gb/s satellite downlink operating at millimeter-wave frequencies. Telecommunications-grade optical components and a high-speed photodiode are used to generate and modulate millimeter-wave carrier frequencies between 90 GHz and 100 GHz at data rates in excess of 10 Gb/s. Experimental results are presented that determine the minimum received power level needed for error-free wireless data transmission. Commercially available W-band power amplifiers are shown to increase the transmitted power level and extend the error-free propagation distance to distances of 10 km. Experimental results and documented atmospheric attenuation values for clouds, fog and rain are used to estimate link budgets for a wireless downlink located on a low-earth-orbiting satellite operating at an altitude of 350 km.

The polarization properties of radiation can contain additional information beyond what is available with only an intensity measurement. A full-Stokes polarimeter is capable of measuring the four Stokes parameters which completely characterizes the polarization of detected radiation. A division of time full-Stokes polarimeter often uses a rotating polarizing element to measure all four Stokes parameters and this rotation can introduce artifacts due to wobbling. In this paper a system is proposed which uses an electrically controlled phase bias instead of a rotating element to create a full-Stokes polarimeter for a millimeter-wave system which utilizes optical up-conversion.

We demonstrate experimentally the ability to shape the point spread function of a distributed aperture millimeter wave imaging system by modifying its aperture phase. We also show how to exploit this capability to perform low-resolution analog image processing. A preliminary investigation of system performance reveals nonuniformity in amplitude response across the array is a major contributor to deviations from predicted PSFs.

We describe and experimentally demonstrate a technique for transmitting microwave signals over an optical fiber and downconverting them to an intermediate frequency at the receiver. The system uses two electrooptic phase modulators, one in the transmitter and the other in the receiver, to optically heterodyne the microwave input signal with a microwave local oscillator. The phase modulated signal is detected at the receiver using an optical delay-line interferometer and a pair of balanced photodectectors. This simple configuration allows downconversion and common-mode noise suppression to be simultaneously realized with relatively high RF-to-IF gain.

In this paper, a novel WDM-to-OTDM conversion system which has a simple setup is proposed. The system is a type of fiber loop consisting of an optical single-side-band (SSB) modulator that is driven by a RF signal source at 10 GHz, a fiber circulator, a single mode fiber coupler, a fiber amplifier and an ultra-narrowband high reflectivity fiber Bragg grating (FBG). The multi-wavelength WDM signals with the spectral sampling interval of 10 GHz (0.08 nm at 1550 nm) is inputted into the system and can be transformed to an OTDM signal carried by one wavelength. The advantages of this multi-wavelength conversion system are that the requirement for the input optical power is low, the wavelength conversion is fast due to the optic-electro effect in a nonlinear optical crystal and the system configuration is compact without need of time delay lines.