Nano-antennas are replicas of antennas that operate at radio-frequencies, but with considerably smaller dimensions when compared with their radio frequency counterparts. Noble metals based nano-antennas have the ability to enhance photoinduced phenomena such as localized electric fields, therefore-they have been used in various applications ranging from optical sensing and imaging to performance improvement of solar cells. However, such nano-structures can be damaged in high power applications such as heat resisted magnetic recording, solar thermo-photovoltaics and nano-scale heat transfer systems. Having a small footprint, nano-antennas cannot handle high fluences (energy density per unit area) and are subject to being damaged at adequately high power (some antennas can handle just a few milliwatts). In addition, given that nano-antennas are passive devices driven by external light sources, the potential damage of the antennas limits their use with high power lasers: this liability can be overcome by employing materials with high melting points such as chromium (Cr) and tungsten (W). In this article, we fabricate chromium and tungsten nano-antennas and demonstrate that they can handle 110 and 300 times higher fluence than that of gold (Au) counterpart, while the electric field enhancement is not significantly reduced.

Nano-antennas on silica or semiconductor substrate cannot handle high power due to their low thermal conductivity. This paper shows that high thermal conductivity substrates such as diamond can handle 20 times higher fluence than silica substrate based nano-antenna without affecting their electrical field enhancement capacities.

Zirconium boride (ZrB12) is an ultra-high temperature material with measured laser damage threshold of 132 mJ/cm(2), higher than in many materials commonly used as saturable absorbers, making it suitable for work in high power laser systems.

In general, noble metals based nano-antennas cannot work at high power applications such as heat resisted magnetic recording, solar thermo-photovoltaics, and nano-scale heat transfer systems. These antennas are prone to being damaged at sufficiently high energy density due to their small footprint and low Tamman temperature. This paper proposes tungsten refractory plasmonic material based nano-antennas as an alternative gold nano-antennas: we show that the antennas can handle 300 times higher fluence than gold (Au) counterpart. In addition, it can achieve 7.22 higher magnitude of electric field intensity than gold antennas.

Magnesium diboride (MgB2) is a well-known superconductor at temperatures below 39 K. At higher temperatures, it behaves as a lossy material. In this paper, we examine the performance of MgB2 nano-particles as saturable absorber in a ytterbium-doped fiber ring laser at room temperature: we show that the nano-particles can produce pulses between 200 and 1700 ns. The dynamics of the saturable absorber are both examined as a stand-alone saturable absorber and in combination with an acousto-optic modulator. We believe, to the best of our knowledge, that this is the first time that MgB2 is used as a saturable absorber in a Q-switched laser.

Having showing agreement with experiments on model systems, finite element tools are being applied to many optical materials that contain nanoparticles. New materials can be quickly screened for applications in optics and photonics and complex media and geometries can be simulated. Laser heating is an invaluable tool for photonic applications to rationally avoid the same bottle neck(heat dissipation) that is prohibiting Moore's Lawscaling of nano-scale transistors in CMOS.

As organic-based electro-optic (EO) modulators continually improve toward meeting the high performance required by new and developing photonic technologies, the challenge of compact and low loss packaging needs to be addressed. Because organic-based EO modulators and RF circuitry are traditionally built on different substrates homogeneous integration would require developing new designs and fabrication processes. In addition, the organic-based EO modulators most often implement microstrip transmission lines for optimal poling and modulation field overlap meaning the ground plane is encapsulated and unavailable for direct contact. In this letter, a heterogeneous RF packaging scheme featuring a wire bond transition between a ceramic feed coplanar waveguide and a thin-film polymer microstrip is presented. The transition introduces less than 1 dB of RF loss at 50 GHz and was demonstrated on an organic-based EO phase modulator which generated optical sidebands out to 40 GHz.

This article presents a microstrip ring resonator technique for characterizing thin film substrates up to 110 GHz. A coupling structure was designed to efficiently couple energy into rings despite the tight microstrip-substrate confinement. Various ring sizes are designed and fabricated, and both dielectric constant and loss tangent results are presented. (C) 2015 Wiley Periodicals, Inc.

As EO phase modulators become more prevalent components in optical and RF applications, the demand increases for high bandwidth and low drive voltage modulators that can easily be integrated into developing photonic technologies. The proposed paper will discuss a device architecture for a phase modulator based on a recently developed organic EO material (OEOM), IKD-1-50 integrated into a PMMA polymer host, using a low-index, photo-curable resin as the cladding layers all on a Si platform. Designs for a TM waveguide and electrode configuration will be presented from theory and modeling, through fabrication to characterization. The EO material serving as the core of the waveguide is poled using a poling stage and monitoring apparatus with same electrodes designed for modulation. Poling procedures have been optimized for this material based on experimentation in simple slab-capacitor characterization devices, and produce in-device r(33) values that are comparable with attenuated total internal reflection measurements. The challenges presented by the instability of OEOMs in common processing conditions have been addressed and a very simple fabrication process has been developed using standard photolithography and reactive ion etching to define an inverted ridge waveguide structure, pattern surrounding electrodes, and prepare usable end facets. Phase modulator characterization results for fabricated and poled devices have been quantified and will be presented. The simplicity of this device architecture on a Si handle allows for integration into various photonic applications.

We measured the electro-optic (EO) coefficients (r33) of thin-film devices made from several monolithic, high number density organic EO chromophores with and without additional charge barrier layers. We found that a cross-linkable benzocyclobutene layer was very effective in suppressing unwanted, leakage current, keeping the effective poling voltage nearly identical to the applied voltage. This barrier layer proved to be superior to a titanium dioxide (TiO2) barrier layer. The suppression of the leakage current in combination with a new chromophore enabled the construction of EO devices that had r33 values in the range of 400–500 pm V−1 with poling fields ≥ 85 V μm−1.

The role of processing dictates the properties and successful integration of OEOMs to an equal extent as chemical synthesis and device design. With redesigned systems, thoughtful processing, and proper molecular and device design, OEOMs will become crucial components of photonic technologies.

Emerging systems requiring large-scale manufacture and monolithic integration of photonic components have created demand for inexpensive and scalable processes for the production of conformal, low-drive voltage, and high bandwidth EO modulators. This paper discusses a device architecture for a phase modulator based on a recently developed organic EO material, IKD-1-50, using low-index, photocurable cladding layers on a Silicon platform. Theory and modeling for a TM waveguide and electrode configuration are presented, followed by the fabrication process and device characterization. The EO material serving as the core of the waveguide is poled using a poling and monitoring apparatus with procedures that were optimized for this material based on experimentation in simple slab-capacitor characterization devices. The challenges presented by the instability of OEOMs under common processing conditions have been addressed and a simple fabrication process has been developed using standard photolithography and reactive ion etching. The characterization methodology for phase modulators will be presented along with the results for modulators fabricated for this study. This study culminates in a V pi L of roughly 3.3 V.cm which is comparable with the record demonstrations in the literature for a TM-mode inverted ridge-waveguide-based EO modulator.

Organic EO materials, sometimes called EO polymers, offer a variety of very promising properties that have improved at remarkable rates over the last decade, and will continue to improve. However, these materials rely on a “poling” process to afford EO activity, which is commonly cited as the bottleneck for the widespread implementation of organic EO material-containing devices. The Solution Phase-Assisted Reorientation of Chromophores (SPARC) is a process that utilizes the mobility of chromophores in the solution phase to afford acentric molecular order during deposition. The electric field can be generated by a corona discharge in a carefully-controlled gas environment. The absence of a poling director during conventional spin deposition forms centric pairs of chromophores which may compromise the efficacy of thermal poling. Direct spectroscopic evidence of linear dichroism in modern organic EO materials has estimated the poling-induced order of the chromophores to be 10-15% of its theoretical maximum, offering the potential for a manyfold enhancement in EO activity if poling is improved. SPARC is designed to overcome these limitations and also to allow the poling of polymeric hosts with temporal thermal (alignment) stabilities greater than the decomposition temperature of the guest chromophore. In this report evidence supporting the theory motivating the SPARC process and the resulting EO activities will be presented. Additionally, the results of trials towards a device demonstration of the SPARC process will be discussed.

Alignment of dipolar chromophores lies at the heart of organic electro-optic materials research. Among all the factors (e. g., external electric field, temperature, conductivity, etc.) affecting alignment efficiency or order parameter, interchromophore electrostatic interaction has been the focus of attention in the last decade. The strength of dipole interaction is highly dependent not only on dipole moment but also on chromophore shape and chromophore number density. Antiparallel interaction is dominant in the solid state of conventional EO chromophores (long and flat) and prevents electro-optic coefficient (r(33)) from scaling with chromophore concentration. Despite the great amount of research along various approaches to enhancing alignment, order parameters of organic EO materials are still low (0.13-0.2 v.s. 1 for a perfect alignment). Antiparallel interaction can be selectively attenuated by attaching bulky groups to the middle part of chromophore. However, it is synthetically challenging to provide sufficient steric protection without causing severe reduction of chromophore concentration. In this paper, we will present the first realization of atom-economic steric protection of chromophore against H-aggregation in all directions and show evidences for the dominance of head-tail interaction over antiparallel interaction of a highly dipolar chromophore. With the novel shape, the EO coefficients of guest-host films of the chromophore do not show attenuation with increasing concentration up to 100 wt%. The dominance of head-tail interaction also enabled fabrication of optical quality thick films from the neat chromophore and allows poling induced alignment to retain at temperatures above the poling temperature - a phenomenon never observed for other chromophores.

An all polymer EO modulator with a simple fabrication process using commercially available cladding materials has been designed, fabricated, and characterized. The result is a low Vπ modulator that is capable of being scaled up to larger scale production. Continued work on this project is being made towards designing an amplitude modulator structure and developing traveling wave transmission line electrodes that will utilize the low dispersion and THz response times of the π-conjugated OEOM system for high frequency operation.

Modern high frequency applications necessitate the utilization of the millimeter wave band. Slot waveguides have previously been used for electro optic modulators as the enhancement of the electric field strength in the slot creates a large overlap with the electro optic material. We present a design that utilizes the field enhancement provided by a slot waveguide geometry for both the optical field and the RF modulating field. The dual RF and optical slot configuration maximizes the overlap of the optical field and the modulating field in the electro optic material, creating the maximum amount of phase change per applied volt of modulating signal. This design presents unique fabrication challenges.

An all-polymer high-frequency Mach-Zehnder modulator that can be fabricated using standard UV lithography is proposed. The optical waveguide structure consists of three polymer layers, two low-index, outer cladding layers and an organic-electro-optic material in a polymer host as the core. Lateral confinement is provided by a trench that is defined in the lower cladding layer, resulting in an inverted electro-optic polymer ridge waveguide. The inverted nature of this trench structure allows for a fabrication process in which the cladding layer is patterned, and the highly sensitive electrooptic material is simply spun on and cured. Microstrip transmission line electrodes patterned on the outer cladding, over the optical waveguides provide the modulation field. Similar devices using CLD1 or AJL8, as the electro-optic material have been numerically analyzed at up to 260GHz, and characterized at frequencies up to 40 GHz, but to date no electrooptic polymer device has been characterized at such high frequencies. A recently developed material, IKD-1-50, with electro-optic coefficients up to five times larger than CLD1 and AJL8 will be utilized as the core layer for the optical waveguide. The greater nonlinearity of these materials will yield a device with a lower Vπ. Additionally, high frequency characterization up to 300GHz will demonstrate the high bandwidth application possibilities of these new materials.

Organic electro-optic materials, or "EO polymers," offer much higher nonlinearities than traditional crystalline materials, making these materials ideal for next generation electro-optic modulators. These materials require an additional processing step known as poling, which reorients the chromophores through the application of a high electric field. This effort will focus on corona poling, where a gas is ionized and the electric field across the sample is applied through the relocation of charged ions. The proposed technique avoids the need to raise the temperature of the material by applying the electric field while the material is deposited in solution phase. This process can overcome the thermal stability tradeoff in many organic electro-optic materials, and preliminary results indicate this process results in an enhancement in the electro-optic activity of the material.

Our recently-proposed optical-RF dual slot modulator achieves nanoscale confinement and can afford extremely low V π modulators. These devices require the convergence of novel materials and processing techniques to integrate organic materials and silicon.