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Single Photon Detection with On-Chip Number Resolving Capability

Chatterjee, Eric N.; Davids, Paul D.; Nenoff, T.M.; Pan, Wei P.; Rademacher, David R.; Soh, Daniel B.

Single photon detection (SPD) plays an important role in many forefront areas of fundamental science and advanced engineering applications. In recent years, rapid developments in superconducting quantum computation, quantum key distribution, and quantum sensing call for SPD in the microwave frequency range. We have explored in this LDRD project a new approach to SPD in an effort to provide deterministic photon-number-resolving capability by using topological Josephson junction structures. In this SAND report, we will present results from our experimental studies of microwave response and theoretical simulations of microwave photon number resolving detector in topological Dirac semimetal Cd3As2. These results are promising for SPD at the microwave frequencies using topological quantum materials.

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Nonreciprocal Frequency Domain Beam Splitter

Physical Review Letters

Otterstrom, Nils T.; Gertler, Shai; Kittlaus, Eric A.; Gehl, M.; Starbuck, Andrew L.; Dallo, Christina M.; Pomerene, Andrew P.; Trotter, Douglas C.; Rakich, Peter T.; Davids, Paul D.; Lentine, Anthony L.

The canonical beam splitter - a fundamental building block of quantum optical systems - is a reciprocal element. It operates on forward- and backward-propagating modes in the same way, regardless of direction. The concept of nonreciprocal quantum photonic operations, by contrast, could be used to transform quantum states in a momentum- and direction-selective fashion. Here we demonstrate the basis for such a nonreciprocal transformation in the frequency domain through intermodal Bragg scattering four-wave mixing (BSFWM). Since the total number of idler and signal photons is conserved, the process can preserve coherence of quantum optical states, functioning as a nonreciprocal frequency beam splitter. We explore the origin of this nonreciprocity and find that the phase-matching requirements of intermodal BSFWM produce an enormous asymmetry (76×) in the conversion bandwidths for forward and backward configurations, yielding ∼25 dB of nonreciprocal contrast over several hundred GHz. We also outline how the demonstrated efficiencies (∼10-4) may be scaled to near-unity values with readily accessible powers and pumping configurations for applications in integrated quantum photonics.

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Microwave response in a topological superconducting quantum interference device

Scientific Reports

Pan, Wei P.; Soh, Daniel B.; Yu, Wenlong; Davids, Paul D.; Nenoff, T.M.

Photon detection at microwave frequency is of great interest due to its application in quantum computation information science and technology. Herein are results from studying microwave response in a topological superconducting quantum interference device (SQUID) realized in Dirac semimetal Cd3As2. The temperature dependence and microwave power dependence of the SQUID junction resistance are studied, from which we obtain an effective temperature at each microwave power level. It is observed the effective temperature increases with the microwave power. This observation of large microwave response may pave the way for single photon detection at the microwave frequency in topological quantum materials.

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Stabilization of ferroelectric phase of Hf0.6Zr0.4O2 on NbN and Nb [slides]

Henry, Michael D.; Davids, Paul D.; Esteves, Giovanni E.; Young, Travis R.; Wolfley, Steven L.; smith, Sean W.; Fields, Shelby S.; Ihlefeld, Jon &.

This work demonstrated both NbN and Nb make good electrodes for stabilizing orthorhombic phase of Hf0.6Zr0.4O2 ferroelectric films. Wake up are < 100 cycles. Pr can be as high as 30 µC/cm2 - respectively 14 and 18 µC/cm2 here. Further, capacitance suggests an orthorhombic phase can be stabilized. Addition of a linear dielectric under modest thickness can tune the Pr and reduce leakage.

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Metal Nitride Electrode Stress and Chemistry Effects on Phase and Polarization Response in Ferroelectric Hf0.5Zr0.5O2 Thin Films

Advanced Materials Interfaces

Fields, Shelby S.; Smith, Sean W.; Fancher, Chris M.; Henry, Michael D.; Wolfley, Steven L.; Sales, Maria G.; Jaszewski, Samantha T.; Rodriguez, Mark A.; Esteves, Giovanni E.; Davids, Paul D.; McDonnell, Stephen J.; Ihlefeld, Jon F.

Ferroelectric phase stability in hafnium oxide is reported to be influenced by factors that include composition, biaxial stress, crystallite size, and oxygen vacancies. In the present work, the ferroelectric performance of atomic layer deposited Hf0.5Zr0.5O2 (HZO) prepared between TaN electrodes that are processed under conditions to induce variable biaxial stresses is evaluated. The post-processing stress states of the HZO films reveal no dependence on the as-deposited stress of the adjacent TaN electrodes. All HZO films maintain tensile biaxial stress following processing, the magnitude of which is not observed to strongly influence the polarization response. Subsequent composition measurements of stress-varied TaN electrodes reveal changes in stoichiometry related to the different preparation conditions. HZO films in contact with Ta-rich TaN electrodes exhibit higher remanent polarizations and increased ferroelectric phase fractions compared to those in contact with N-rich TaN electrodes. HZO films in contact with Ta-rich TaN electrodes also have higher oxygen vacancy concentrations, indicating that a chemical interaction between the TaN and HZO layers ultimately impacts the ferroelectric orthorhombic phase stability and polarization performance. The results of this work demonstrate a necessity to carefully consider the role of electrode processing and chemistry on performance of ferroelectric hafnia films.

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Development of Quantum Interconnects (QuICs) for Next-Generation Information Technologies

PRX Quantum

Awschalom, David; Berggren, Karl K.; Bernien, Hannes; Bhave, Sunil; Carr, Lincoln D.; Davids, Paul D.; Economou, Sophia E.; Englund, Dirk; Faraon, Andrei; Fejer, Martin; Guha, Saikat; Gustafsson, Martin V.; Hu, Evelyn; Jiang, Liang; Kim, Jungsang; Korzh, Boris; Kumar, Prem; Kwiat, Paul G.; Lončar, Marko; Lukin, Mikhail D.; Miller, David A.B.; Monroe, Christopher; Nam, Sae W.; Narang, Prineha; Orcutt, Jason S.; Raymer, Michael G.; Safavi-Naeini, Amir H.; Spiropulu, Maria; Srinivasan, Kartik; Sun, Shuo; Vučković, Jelena; Waks, Edo; Walsworth, Ronald; Weiner, Andrew M.; Zhang, Zheshen

Just as "classical"information technology rests on a foundation built of interconnected information-processing systems, quantum information technology (QIT) must do the same. A critical component of such systems is the "interconnect,"a device or process that allows transfer of information between disparate physical media, for example, semiconductor electronics, individual atoms, light pulses in optical fiber, or microwave fields. While interconnects have been well engineered for decades in the realm of classical information technology, quantum interconnects (QuICs) present special challenges, as they must allow the transfer of fragile quantum states between different physical parts or degrees of freedom of the system. The diversity of QIT platforms (superconducting, atomic, solid-state color center, optical, etc.) that will form a "quantum internet"poses additional challenges. As quantum systems scale to larger size, the quantum interconnect bottleneck is imminent, and is emerging as a grand challenge for QIT. For these reasons, it is the position of the community represented by participants of the NSF workshop on "Quantum Interconnects"that accelerating QuIC research is crucial for sustained development of a national quantum science and technology program. Given the diversity of QIT platforms, materials used, applications, and infrastructure required, a convergent research program including partnership between academia, industry, and national laboratories is required.

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Nanoantenna-Enhanced Resonant Detectors for Improved Infrared Detector Performance

Goldflam, Michael G.; Anderson, Evan M.; Fortune, Torben R.; Klem, John F.; Hawkins, Samuel D.; Davids, Paul D.; Campione, Salvatore; Pung, Aaron J.; Webster, Preston T.; Weiner, Phillip H.; Finnegan, Patrick S.; Wendt, Joel R.; Wood, Michael G.; Haines, Chris H.; Coon, Wesley T.; Olesberg, Jonathon T.; Shaner, Eric A.; Kadlec, Clark N.; Beechem, Thomas E.; Sinclair, Michael B.; Tauke-Pedretti, Anna; Kim, Jin K.; Peters, D.W.

Abstract not provided.

Compositional dependence of linear and nonlinear optical response in crystalline hafnium zirconium oxide thin films

Journal of Applied Physics

Ihlefeld, Jon F.; Luk, Ting S.; Smith, Sean S.; Fields, Shelby S.; Jaszewski, Samantha T.; Hirt, Daniel M.; Riffe, Will T.; Bender, Scott; Constantin, Costel; Ayyasamy, Mukil V.; Balachandran, Prasanna V.; Lu, Ping L.; Henry, Michael D.; Davids, Paul D.

Composition dependence of second harmonic generation, refractive index, extinction coefficient, and optical bandgap in 20 nm thick crystalline Hf1-xZrxO2 (0 ≤ x ≤ 1) thin films is reported. The refractive index exhibits a general increase with increasing ZrO2 content with all values within the range of 1.98-2.14 from 880 nm to 400 nm wavelengths. A composition dependence of the indirect optical bandgap is observed, decreasing from 5.81 eV for HfO2 to 5.17 eV for Hf0.4Zr0.6O2. The bandgap increases for compositions with x > 0.6, reaching 5.31 eV for Hf0.1Zr0.9O2. Second harmonic signals are measured for 880 nm incident light. The magnitude of the second harmonic signal scales with the magnitude of the remanant polarization in the composition series. Film compositions that display near zero remanent polarizations exhibit minimal second harmonic generation while those with maximum remanent polarization also display the largest second harmonic signal. The results are discussed in the context of ferroelectric phase assemblage in the hafnium zirconium oxide films and demonstrate a path toward a silicon-compatible integrated nonlinear optical material.

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Electrical power generation from moderate-temperature radiative thermal sources

Science

Davids, Paul D.; Kirsch, Jared K.; Starbuck, Andrew L.; Jarecki, Robert L.; Shank, Joshua S.; Peters, D.W.

Moderate-temperature thermal sources (100° to 400°C) that radiate waste heat are often the by-product of mechanical work, chemical or nuclear reactions, or information processing. We demonstrate conversion of thermal radiation into electrical power using a bipolar grating-coupled complementary metal-oxide-silicon (CMOS) tunnel diode. A two-step photon-assisted tunneling charge pumping mechanism results in separation of charge carriers in pn-junction wells leading to a large open-circuit voltage developed across a load. Electrical power generation from a broadband blackbody thermal source has been experimentally demonstrated with converted power densities of 27 to 61 microwatts per square centimeter for thermal sources between 250° and 400°C. Scalable, efficient conversion of radiated waste heat into electrical power can be used to reduce energy consumption or to power electronics and sensors.

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Infrared Nanoantenna-Coupled Rectenna for Energy Harvesting

IEEE Aerospace Conference Proceedings

Shank, Joshua S.; Kadlec, E.A.; Peters, D.W.; Davids, Paul D.

Energy harvesting from relatively low-temperature heat sources is important in applications where long-term power sources are needed such as deep space radioisotope thermoelectric generators (RTGs). Current solutions exhibit low efficiency, require exotic materials and structures, and direct contact to the heat source. While the infrared rectenna is currently low efficiency, the path exists for high-efficiency solid state devices. We have made a scalable design using standard CMOS processes, allowing for large-area fabrication. This would allow devices to be made on the wafer scale using existing fabrication technology. The rectenna has the advantage of using radiated power, thus it does not require direct contact to the hot source, but instead must only view the source. This will simplify packaging requirements and make a more robust system. The devices are monolithic and thus robust to adverse operating environments. Here we will discuss the rectenna's physics of operation, particularly light coupling into the structure. Incoming light is coupled to a metal-oxide-semiconductor (MOS) tunnel diode via a broad-area nanoantenna. The nanoantenna consists of a subwavelength metal patterning that concentrates the light into the tunnel diode where the optical signal is rectified. Both the nanoantenna and tunnel diode are distributed devices utilizing the entire area of the surface. The nanoantenna also serves as one contact of the tunnel diode. This direct integration of the nanoantenna and diode overcomes the resistive loss limitations found in prior IR rectenna concepts that resembled microwave rectenna designs scaled down to infrared sizes. We will show simulation and experimental results of fabricated devices. Simulations of the optical fields in the tunnel gap are illustrative of device operation and will be discussed. The measured infrared photocurrent is compared to simulated expectations. Far-field radiation power conversion is demonstrated using standard radiometric techniques and correlated with the rectified current response. We discuss thermal modelling of the localized heat generation within the rectenna structure to demonstrate the lack of a thermoelectric response. Lastly, we discuss future directions of work to improve power conversion efficiency.

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Phase optimization of a silicon photonic two-dimensional electro-optic phased array

Optics InfoBase Conference Papers

Gehl, M.; Hoffman, Galen H.; Davids, Paul D.; Starbuck, Andrew L.; Dallo, Christina M.; Barber, Zeb; Kadlec, Emil; Mohan, R.K.; Crouch, Stephen; Long, Christopher M.

Phase errors in large optical phased arrays degrade beam quality and must be actively corrected. Using a novel, low-power electro-optic design with matched pathlengths, we demonstrate simplified optimization and reduced sensitivity to wavelength and temperature.

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Power Generation from a Radiative Thermal Source Using a Large-Area Infrared Rectenna

Physical Review Applied

Shank, Joshua S.; Kadlec, Emil A.; Jarecki, Robert L.; Starbuck, Andrew L.; Howell, Stephen W.; Peters, D.W.; Davids, Paul D.

Electrical power generation from a moderate-temperature thermal source by means of direct conversion of infrared radiation is important and highly desirable for energy harvesting from waste heat and micropower applications. Here, we demonstrate direct rectified power generation from an unbiased large-area nanoantenna-coupled tunnel diode rectifier called a rectenna. Using a vacuum radiometric measurement technique with irradiation from a temperature-stabilized thermal source, a generated power density of 8 nW/cm2 is observed at a source temperature of 450 °C for the unbiased rectenna across an optimized load resistance. The optimized load resistance for the peak power generation for each temperature coincides with the tunnel diode resistance at zero bias and corresponds to the impedance matching condition for a rectifying antenna. Current-voltage measurements of a thermally illuminated large-area rectenna show current zero crossing shifts into the second quadrant indicating rectification. Photon-assisted tunneling in the unbiased rectenna is modeled as the mechanism for the large short-circuit photocurrents observed where the photon energy serves as an effective bias across the tunnel junction. The measured current and voltage across the load resistor as a function of the thermal source temperature represents direct current electrical power generation.

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Density matrix approach to photon-assisted tunneling in the transfer Hamiltonian formalism

Physical Review B

Davids, Paul D.; Shank, Joshua S.

The transfer Hamiltonian tunneling current is derived in a time-dependent density matrix formulation and is used to examine photon-assisted tunneling. Bardeen's tunneling expression arises as the result of first-order perturbation theory in a mean-field expansion of the density matrix. Photon-assisted tunneling from confined electromagnetic fields in the forbidden tunnel barrier region occurs due to time-varying polarization and wave-function overlap in the gap which leads to a nonzero tunneling current in asymmetric device structures, even in an unbiased state. The photon energy is seen to act as an effective temperature-dependent bias in a uniform barrier asymmetric tunneling example problem. Higher-order terms in the density matrix expansion give rise to multiphoton enhanced tunneling currents that can be considered an extension of nonlinear optics where the nonlinear conductance plays a similar role as the nonlinear susceptibilities in the continuity equations.

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Realistic full wave modeling of focal plane array pixels

Applied Computational Electromagnetics Society Journal

Campione, Salvatore; Warne, Larry K.; Jorgenson, Roy E.; Davids, Paul D.; Peters, D.W.

In this paper we investigate full-wave simulations of realistic implementations of multifunctional nanoantenna enabled detectors (NEDs). We focus on a 2x2 pixelated array structure that supports two wavelengths of operation. We design each resonating structure independently using full-wave simulations with periodic boundary conditions mimicking the whole infinite array. We then construct a supercell made of a 2x2 pixelated array with periodic boundary conditions mimicking the full NED; in this case, however, each pixel comprises 10-20 antennas per side. In this way, the cross-talk between contiguous pixels is accounted for in our simulations. We observe that, even though there are finite extent effects, the pixels work as designed, each responding at the respective wavelength of operation. This allows us to stress that realistic simulations of multifunctional NEDs need to be performed to verify the design functionality by taking into account finite extent and cross-talk effects.

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Integrating Resonant Structures with IR Detectors

Goldflam, Michael G.; Goldflam, Michael G.; Anderson, Evan M.; Anderson, Evan M.; Campione, Salvatore; Campione, Salvatore; Coon, Wesley T.; Coon, Wesley T.; Davids, Paul D.; Davids, Paul D.; Fortune, Torben R.; Fortune, Torben R.; Hawkins, Samuel D.; Hawkins, Samuel D.; Kadlec, Clark N.; Kadlec, Clark N.; Kadlec, Emil A.; Kadlec, Emil A.; Kim, Jin K.; Kim, Jin K.; Klem, John F.; Klem, John F.; Shaner, Eric A.; Shaner, Eric A.; Sinclair, Michael B.; Sinclair, Michael B.; Tauke-Pedretti, Anna; Tauke-Pedretti, Anna; Warne, Larry K.; Warne, Larry K.; Wendt, J.R.; Wendt, J.R.; Beechem, Thomas E.; Beechem, Thomas E.; Howell, Stephen W.; Howell, Stephen W.; McDonald, Anthony E.; McDonald, Anthony E.; Ruiz, Isaac R.; Ruiz, Isaac R.

Abstract not provided.

Improved infrared detection using nanoantennas

International Conference on Optical MEMS and Nanophotonics

Peters, D.W.; Sinclair, Michael B.; Goldflam, Michael G.; Warne, Larry K.; Campione, Salvatore; Kim, Jin K.; Davids, Paul D.; Tauke-Pedretti, Anna; Wendt, J.R.; Klem, John F.; Hawkins, Samuel D.; Parameswaran, Sivasubramanian P.; Coon, W.T.; Keeler, G.A.; Fortune, Torben R.

We examine integration of a patterned metal nanoantenna (or metasurface) directly onto long-wave infrared detectors. These structures show significantly improved external quantum efficiency compared to their traditional counterparts. We will show simulation and experimental results.

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Vacuum radiometry of an infrared nanoantenna-coupled tunnel diode rectenna

International Conference on Optical MEMS and Nanophotonics

Davids, Paul D.; Kadlec, Emil A.; Shank, Joshua S.; Peters, D.W.; Howell, Stephen W.

We examine the vacuum infrared photoresponse of a large-area nanoantenna-coupled tunnel diode rectenna resulting from thermal radiation from a temperature controlled heater. The measured infrared photocurrent is obtained as a function of the source temperature, sample distance and view factor. Far-field radiation power conversion is examined using standard radiometric techniques and correlated with the rectified current response.

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Resonantly enhanced infrared detectors based on type-II superlattice absorbers

Goldflam, Michael G.; Goldflam, Michael G.; Campione, Salvatore; Campione, Salvatore; Kadlec, Emil A.; Kadlec, Emil A.; Hawkins, Samuel D.; Hawkins, Samuel D.; Coon, Wesley T.; Coon, Wesley T.; Fortune, Torben R.; Fortune, Torben R.; Parameswaran, Sivasubramanian P.; Parameswaran, Sivasubramanian P.; Keeler, Gordon A.; Keeler, Gordon A.; Klem, John F.; Klem, John F.; Tauke-Pedretti, Anna; Tauke-Pedretti, Anna; Shaner, Eric A.; Shaner, Eric A.; Davids, Paul D.; Davids, Paul D.; Warne, Larry K.; Warne, Larry K.; Wendt, J.R.; Wendt, J.R.; Kim, Jin K.; Kim, Jin K.; Peters, D.W.; Peters, D.W.

Abstract not provided.

Next-generation infrared focal plane arrays for high-responsivity low-noise applications

IEEE Aerospace Conference Proceedings

Goldflam, Michael G.; Hawkins, Samuel D.; Parameswaran, Sivasubramanian P.; Tauke-Pedretti, Anna; Warne, Larry K.; Peters, D.W.; Campione, Salvatore; Coon, W.T.; Keeler, Gordon A.; Shaner, Eric A.; Wendt, J.R.; Kadlec, Emil A.; Fortune, Torben R.; Klem, John F.; Davids, Paul D.; Kim, Jin K.

High-quality infrared focal plane arrays (FPAs) are used in many satellite, astronomical, and terrestrial applications. These applications require highly-sensitive, low-noise FPAs, and therefore do not benefit from advances made in low-cost thermal imagers where reducing cost and enabling high-temperature operation drive device development. Infrared detectors used in FPAs have been made for decades from alloys of mercury cadmium telluride (MCT). These infrared detectors are nearing the believed limit of their performance. This limit, known in the infrared detector community as Rule 07, dictates the dark current floor for MCT detectors, in their traditional architecture, for a given temperature and cutoff wavelength. To overcome the bounds imposed by Rule 07, many groups are working on detector compounds other than MCT. We focus on detectors employing III-V-based gallium-free InAsSb superlattice active regions while also changing the basic architecture of the pixel to improve signal-to-noise. Our architecture relies on a resonant, metallic, subwavelength nanoantenna patterned on the absorber surface, in combination with a Fabry-Pérot cavity, to couple the incoming radiation into tightly confined modes near the nanoantenna. This confinement of the incident energy in a thin layer allows us to greatly reduce the volume of the absorbing layer to a fraction of the free-space wavelength, yielding a corresponding reduction in dark current from spontaneously generated electron-hole pairs in the absorber material. This architecture is detector material agnostic and could be applied to MCT detector structures as well, although we focus on using superlattice antimonide-based detector materials. This detector concept has been applied to both mid-wave (3-5 μm) and longwave (8-12 μm) infrared detectors and absorbers. Here we examine long-wave devices, as these detectors currently have a larger gap between desired device performance and that of currently existing detectors. The measured structures show an external quantum efficiency exceeding 50%. We present a comparison of the modeled and measured photoresponse of these detectors and compare these detectors to currently available commercial detectors using relevant metrics such as external quantum efficiency. We also discuss modeling of crosstalk between adjacent pixels and its influence on the potential for a dual-wavelength detector. Finally, we evaluate potential advances in these detectors that may occur in the near future.

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Silicon photonic transceiver circuit for highspeed polarization-based discrete variable quantum key distribution

Optics Express

Cai, Hong; Long, Christopher M.; DeRose, Christopher T.; Boynton, Nicholas; Urayama, Junji U.; Camacho, Ryan C.; Pomerene, Andrew P.; Starbuck, Andrew L.; Trotter, Douglas C.; Davids, Paul D.; Lentine, Anthony L.

We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.

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Designing graphene absorption in a multispectral plasmon-enhanced infrared detector

Optics Express

Goldflam, Michael G.; Fei, Zhe; Ruiz, Isaac R.; Howell, Stephen W.; Davids, Paul D.; Peters, D.W.; Beechem, Thomas E.

We have examined graphene absorption in a range of graphene-based infrared devices that combine either monolayer or bilayer graphene with three different gate dielectrics. Electromagnetic simulations show that the optical absorption in graphene in these devices, an important factor in a functional graphene-based detector, is strongly dielectricdependent. These simulations reveal that plasmonic excitation in graphene can significantly influence the percentage of light absorbed in the entire device, as well as the graphene layer itself, with graphene absorption exceeding 25% in regions where plasmonic excitation occurs. Notably, the dielectric environment of graphene has a dramatic influence on the strength and wavelength range over which the plasmons can be excited, making dielectric choice paramount to final detector tunability and sensitivity.

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High speed ultra-broadband amplitude modulators with ultrahigh extinction >65 dB

Optics Express

Liu, Sheng L.; Cai, Hong; Derose, C.T.; Davids, Paul D.; Pomerene, Andrew P.; Starbuck, Andrew L.; Trotter, D.C.; Camacho, Ryan C.; Urayama, Junji U.; Lentine, Anthony L.

We experimentally demonstrate ultrahigh extinction ratio (>65 dB) amplitude modulators (AMs) that can be electrically tuned to operate across a broad spectral range of 160 nm from 1480-1640 nm and 95 nm from 1280-1375 nm. Our on-chip AMs employ one extra coupler compared with conventional Mach-Zehnder interferometers (MZI), thus form a cascaded MZI (CMZI) structure. Either directional or adiabatic couplers are used to compose the CMZI AMs and experimental comparisons are made between these two different structures. We investigate the performance of CMZI AMs under extreme conditions such as using 95:5 split ratio couplers and unbalanced waveguide losses. Electro-optic phase shifters are also integrated in the CMZI AMs for high-speed operation. Finally, we investigate the output optical phase when the amplitude is modulated, which provides us valuable information when both amplitude and phase are to be controlled. Our demonstration not only paves the road to applications such as quantum information processing that requires high extinction ratio AMs but also significantly alleviates the tight fabrication tolerance needed for large-scale integrated photonics.

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Simulations of realistic multifunctional nanoantenna enabled detectors

2017 International Applied Computational Electromagnetics Society Symposium - Italy, ACES 2017

Campione, Salvatore; Warne, Larry K.; Jorgenson, Roy E.; Davids, Paul D.; Peters, D.W.

The goal of this paper is to investigate full-wave simulations of realistic implementations of multifunctional nanoantenna enabled detectors (NEDs). We realize a 2×2 pixelated array structure that supports two wavelengths of operation. After designing each resonating structure independently using full-wave simulations with periodic boundary conditions mimicking the whole infinite array, we construct a supercell made of a 2×2 pixelated array with periodic boundary conditions mimicking the full NED. In the NED, each pixel comprises 10-20 nanoantennas. Our simulations account for the cross-talk between contiguous pixels. We observe that, even though there are finite extent effects, the pixels work as designed, each responding at the respective wavelength of operation. We want to stress that realistic simulations of multifunctional NEDs need to be performed to verify the design functionality by taking into account finite extent and cross-talk effects.

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Three dimensional metafilms with dual channel unit cells

Applied Physics Letters

Burckel, David B.; Campione, Salvatore; Davids, Paul D.; Sinclair, Michael B.

Three-dimensional (3D) metafilms composed of periodic arrays of silicon unit cells containing single and multiple micrometer-scale vertical split ring resonators (SRRs) per unit cell were fabricated. In contrast to planar and stacked planar structures, these 3D metafilms have a thickness t ∼ λd/4, allowing for classical thin film effects in the long wavelength limit. The infrared specular far-field scattering response was measured for metafilms containing one and two resonators per unit cell and compared to numerical simulations. Excellent agreement in the frequency region below the onset of diffractive scattering was obtained. For dense arrays of unit cells containing single SRRs, normally incident linearly polarized plane waves which do not excite a resonant response result in thin film interference fringes in the reflected spectra and are virtually indistinguishable from the scattering response of an undecorated array of unit cells. For the resonant linear polarization, the specular reflection for arrays is highly dependent on the SRR orientation on the vertical face for gap-up, gap-down, and gap-right orientations. For dense arrays of unit cells containing two SRRs per unit cell positioned on adjacent faces, the specular reflection spectra are slightly modified due to near-field coupling between the orthogonally oriented SRRs but otherwise exhibit reflection spectra largely representative of the corresponding single-SRR unit cell structures. The ability to pack the unit cell with multiple inclusions which can be independently excited by choice of incident polarization suggests the construction of dual-channel films where the scattering response is selected by altering the incident polarization.

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Demonstration of a silicon photonic transceiver for polarization-based discrete variable quantum key distribution

Optics InfoBase Conference Papers

Cai, Hong; Long, Christopher M.; DeRose, Christopher T.; Boynton, Nicholas; Urayama, Junji U.; Pomerene, Andrew P.; Starbuck, Andrew L.; Trotter, Douglas C.; Davids, Paul D.; Lentine, Anthony L.

We demonstrate a silicon photonic transceiver circuit to implement polarization encoding/decoding for DV-QKD. The circuit is capable of encoding BB84 states with >30 dB PER and decoding with >20 dB ER.

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Ultrahigh extinction on-chip amplitude modulators with broadband operation

Optics InfoBase Conference Papers

Liu, Sheng L.; Cai, Hong; DeRose, Christopher T.; Davids, Paul D.; Pomerene, Andrew P.; Starbuck, Andrew L.; Trotter, Douglas C.; Urayama, Junji U.; Camacho, Ryan C.; Lentine, Anthony L.

We experimentally demonstrate amplitude modulators (AMs) with >65 dB extinction across over a 160 nm spectral range. The output optical phase response is also characterized when the amplitude is modulated.

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Photon-Phonon-Enhanced Infrared Rectification in a Two-Dimensional Nanoantenna-Coupled Tunnel Diode

Physical Review Applied

Kadlec, Emil A.; Jarecki, Robert L.; Starbuck, Andrew L.; Peters, D.W.; Davids, Paul D.

The interplay of strong infrared photon-phonon coupling with electromagnetic confinement in nanoscale devices is demonstrated to have a large impact on ultrafast photon-assisted tunneling in metal-oxide-semiconductor (MOS) structures. Infrared active optical phonon modes in polar oxides lead to strong dispersion and enhanced electric fields at material interfaces. We find that the infrared dispersion of SiO2 near a longitudinal optical phonon mode can effectively impedance match a photonic surface mode into a nanoscale tunnel gap that results in large transverse-field confinement. An integrated 2D nanoantenna structure on a distributed large-area MOS tunnel-diode rectifier is designed and built to resonantly excite infrared surface modes and is shown to efficiently channel infrared radiation into nanometer-scale gaps in these MOS devices. This enhanced-gap transverse-electric field is converted to a rectified tunneling displacement current resulting in a dc photocurrent. We examine the angular and polarization-dependent spectral photocurrent response of these 2D nanoantenna-coupled tunnel diodes in the photon-enhanced tunneling spectral region. Our 2D nanoantenna-coupled infrared tunnel-diode rectifier promises to impact large-area thermal energy harvesting and infrared direct detectors.

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Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

Applied Physics Letters

Goldflam, Michael G.; Kadlec, Emil A.; Olson, B.V.; Klem, John F.; Hawkins, Samuel D.; Parameswaran, Sivasubramanian P.; Coon, W.T.; Keeler, Gordon A.; Fortune, Torben R.; Tauke-Pedretti, Anna; Wendt, J.R.; Shaner, Eric A.; Davids, Paul D.; Kim, Jin K.; Peters, D.W.

We examined the spectral responsivity of a 1.77 μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber's subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency. The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.

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High performance waveguide-coupled Ge-on-Si linear mode avalanche photodiodes

Optics Express

Martinez, Nicolas J.D.; DeRose, Christopher T.; Brock, Reinhard W.; Starbuck, Andrew L.; Pomerene, Andrew P.; Lentine, Anthony L.; Trotter, Douglas C.; Davids, Paul D.

We present experimental results for a selective epitaxially grown Ge-on-Si separate absorption and charge multiplication (SACM) integrated waveguide coupled avalanche photodiode (APD) compatible with our silicon photonics platform. Epitaxially grown Ge-on-Si waveguide-coupled linear mode avalanche photodiodes with varying lateral multiplication regions and different charge implant dimensions are fabricated and their illuminated device characteristics and high-speed performance is measured. We report a record gain-bandwidth product of 432 GHz for our highest performing waveguide-coupled avalanche photodiode operating at 1510nm. Bit error rate measurements show operation with BER< 10-12, in the range from -18.3 dBm to -12 dBm received optical power into a 50 Ω load and open eye diagrams with 13 Gbps pseudo-random data at 1550 nm.

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An adiabatic/diabatic polarization beam splitter

5th IEEE Photonics Society Optical Interconnects Conference, OI 2016

Cai, Hong; Boynton, Nicholas; Lentine, Anthony L.; Pomerene, Andrew P.; Trotter, Douglas C.; Starbuck, Andrew L.; Davids, Paul D.; DeRose, Christopher T.

We demonstrate an on-chip polarization beam splitter (PBS), which is adiabatic for the transverse magnetic mode, and diabatic for the transverse electric mode. The PBS has a simple structure that is tolerant to manufacturing variations and exhibits high polarization extinction ratios over a wide bandwidth.

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Silicon photonics platform for national security applications

IEEE Aerospace Conference Proceedings

Lentine, Anthony L.; DeRose, Christopher T.; Davids, Paul D.; Martinez, Nicolas J.D.; Zortman, William A.; Cox, Jonathan A.; Jones, Adam; Trotter, Douglas C.; Pomerene, Andrew P.; Starbuck, Andrew L.; Savignon, Daniel J.; Bauer, Todd B.; Wiwi, Michael W.; Chu, Patrick B.

We review Sandia's silicon photonics platform for national security applications. Silicon photonics offers the potential for extensive size, weight, power, and cost (SWaP-c) reductions compared to existing III-V or purely electronics circuits. Unlike most silicon photonics foundries in the US and internationally, our silicon photonics is manufactured in a trusted environment at our Microsystems and Engineering Sciences Application (MESA) facility. The Sandia fabrication facility is certified as a trusted foundry and can therefore produce devices and circuits intended for military applications. We will describe a variety of silicon photonics devices and subsystems, including both monolithic and heterogeneous integration of silicon photonics with electronics, that can enable future complex functionality in aerospace systems, principally focusing on communications technology in optical interconnects and optical networking.

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Application of plasmonic subwavelength structuring to enhance infrared detection

Proceedings of SPIE - The International Society for Optical Engineering

Peters, David W.; Davids, Paul D.; Kim, Jin K.; Leonhardt, Darin L.; Beechem, Thomas E.; Howell, Stephen W.; Ohta, Taisuke O.; Wendt, J.R.; Montoya, John A.

Nanoantennas are an enabling technology for visible to terahertz components and may be used with a variety of detector materials. We have integrated subwavelength patterned metal nanoantennas with various detector materials for infrared detection: midwave infrared indium gallium arsenide antimonide detectors, longwave infrared graphene detectors, and shortwave infrared germanium detectors. Nanoantennas offer a means to make infrared detectors much thinner, thus lowering the dark current and improving performance. The nanoantenna converts incoming plane waves to more tightly bound and concentrated surface waves. The active material only needs to extend as far as these bound fields. In the case of graphene detectors, which are only one or two atomic layers thick, such field concentration is a necessity for usable device performance, as single pass absorption is insufficient. The nanoantenna is thus the enabling component of these thin devices. However nanoantenna integration and fabrication vary considerably across these platforms as do the considerations taken into account during design. Here we discuss the motivation for these devices and show examples for the three material systems. Characterization results are included for the midwave infrared detector. © 2014 SPIE.

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Nanoantenna-enabled midwave infrared focal plane arrays

Proceedings of SPIE - The International Society for Optical Engineering

Peters, D.W.; Reinke, Charles M.; Davids, Paul D.; Klem, John F.; Leonhardt, Darin L.; Wendt, J.R.; Kim, Jin K.; Samora, S.

We demonstrate the effects of integrating a nanoantenna to a midwave infrared (MWIR) focal plane array (FPA). We model an antenna-coupled photodetector with a nanoantenna fabricated in close proximity to the active material of a photodetector. This proximity allows us to take advantage of the concentrated plasmonic fields of the nanoantenna. The role of the nanoantenna is to convert free-space plane waves into surface plasmons bound to a patterned metal surface. These plasmonic fields are concentrated in a small volume near the metal surface. Field concentration allows for a thinner layer of absorbing material to be used in the photodetector design and promises improvements in cutoff wavelength and dark current (higher operating temperature). While the nanoantenna concept may be applied to any active photodetector material, we chose to integrate the nanoantenna with an InAsSb photodiode. The geometry of the nanoantenna-coupled detector is optimized to give maximal carrier generation in the active region of the photodiode, and fabrication processes must be altered to accommodate the nanoantenna structure. The intensity profiles and the carrier generation rates in the photodetector active layers are determined by finite element method simulations, and iteration between optical nanoantenna simulation and detector modeling is used to optimize the device structure. © 2012 SPIE.

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Plasmonic integrated optics: Going the last few microns

2010 IEEE Photonics Society Summer Topical Meeting Series, PHOSST 2010

Davids, Paul D.

Plasmonic integrated optics is an attempt to bridge the length scale gap between optics and nanometer scale electronic devices. Here we present a hybrid optical interconnect scheme which utilizes low loss dielectric waveguides for global interconnection and plasmonic structures for tightly confining light for local routing and mode manipulation.

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Transmissive infrared frequency selective surfaces and infrared antennas : final report for LDRD 105749

Davids, Paul D.; Cruz-Cabrera, A.A.; Basilio, Lorena I.; Wendt, J.R.; Kemme, S.A.; Johnson, William Arthur.; Loui, Hung L.

Plasmonic structures open up new opportunities in photonic devices, sometimes offering an alternate method to perform a function and sometimes offering capabilities not possible with standard optics. In this LDRD we successfully demonstrated metal coatings on optical surfaces that do not adversely affect the transmission of those surfaces at the design frequency. This technology could be applied as an RF noise blocking layer across an optical aperture or as a method to apply an electric field to an active electro-optic device without affecting optical performance. We also demonstrated thin optical absorbers using similar patterned surfaces. These infrared optical antennas show promise as a method to improve performance in mercury cadmium telluride detectors. Furthermore, these structures could be coupled with other components to lead to direct rectification of infrared radiation. This possibility leads to a new method for infrared detection and energy harvesting of infrared radiation.

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