Engineering Commons^™

Implementing Commercial Inverse Design Tools For Compact, Phase-Encoded, Plasmonic Digital Logic Devices, Michael Efseaff, Kyle Wynne, Krishna Narayan, Mark C. Harrison

Engineering Faculty Articles and Research

Numerical simulations have become an essential design tool in the field of photonics, especially for nanophotonics. In particular, 3D finite-difference-time-domain (FDTD) simulations are popular for their powerful design capabilities. Increasingly, researchers are developing or using inverse design tools to improve device footprints and performance. These tools often make use of 3D FDTD simulations and the adjoint optimization method. We implement a commercial inverse design tool with these features for several plasmonic devices that push the boundaries of the tool. We design a logic gate with complex design requirements as well as a y-splitter and waveguide crossing. With minimal code changes, …

Utilizing Inverse Design To Create Plasmonic Waveguide Devices, Michael Efseaff, Kyle Wynne, Mark C. Harrison

Engineering Faculty Articles and Research

In modern communications networks, data is transmitted over long distances using optical fibers. At nodes in the network, the data is converted to an electrical signal to be processed, and then converted back into an optical signal to be sent over fiber optics. This process results in higher power consumption and adds to transmission time. However, by processing the data optically, we can begin to alleviate these issues and surpass systems which rely on electronics. One promising approach for this is plasmonic devices. Plasmonic waveguide devices have smaller footprints than silicon photonics for more compact photonic integrated circuits, although they …

Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li

Mathematical Sciences Faculty Research

© 2020 The Author(s) In this paper, we investigate a system of governing equations for modeling wave propagation in graphene. Compared to our previous work (Yang et al., 2020), here we re-investigate the governing equations by eliminating two auxiliary unknowns from the original model. A totally new stability for the model is established for the first time. Since the finite element scheme proposed in Yang et al. (2020) is only first order in time, here we propose two new schemes with second order convergence in time for the simplified modeling equations. Discrete stabilities inheriting exactly the same form as the …

Groove Shape-Dependent Absorption Enhancement Of 850 Nm Msm Photodetectors With Nano-Gratings., Narottam Das, Ayman Karar, Mikhail Vasiliev, Chee Leong Tan, Kamal Alameh, Yong Tak Lee

Mikhail Vasiliev

Finite difference time-domain (FDTD) analysis is used to investigate the light absorption enhancement factor dependence on the groove shape of the nano-gratings etched into the surfaces of metal-semiconductor-metal photodetector (MSM-PD) structures. By patterning the MSM-PDs with optimized nano-gratings a significant improvement in light absorption near the design wavelength is achieved through plasmon-assisted electric field concentration effects. Simulation results show about 50 times light absorption enhancement for 850 nm light due to improved optical signal propagation through the nano-gratings.

Groove Shape-Dependent Absorption Enhancement Of 850 Nm Msm Photodetectors With Nano-Gratings., Narottam Das, Ayman Karar, Mikhail Vasiliev, Chee Leong Tan, Kamal Alameh, Yong Tak Lee

Mikhail Vasiliev

Finite difference time-domain (FDTD) analysis is used to investigate the light absorption enhancement factor dependence on the groove shape of the nano-gratings etched into the surfaces of metal-semiconductor-metal photodetector (MSM-PD) structures. By patterning the MSM-PDs with optimized nano-gratings a significant improvement in light absorption near the design wavelength is achieved through plasmon-assisted electric field concentration effects. Simulation results show about 50 times light absorption enhancement for 850 nm light due to improved optical signal propagation through the nano-gratings.

Tunable Optical Nanocavity Of Iron-Garnet With A Buried Metal Layer, Alexey N. Kuz'michev, Lars E. Kreilkamp, Mohammed Nur-E-Alam, Evgeni Bezus, Mikhail Vasilev, Iliya A. Akimov, Kamal Alameh, Manfred Bayer, Vladimir I. Belotelov

Research outputs 2014 to 2021

We report on the fabrication and characterization of a novel magnetophotonic structure designed as iron garnet based magneto-optical nanoresonator cavity constrained by two noble metal mirrors. Since the iron garnet layer requires annealing at high temperatures, the fabrication process can be rather challenging. Special approaches for the protection of metal layers against oxidation and morphological changes along with a special plasma-assisted polishing of the iron garnet layer surface were used to achieve a 10-fold enhancement of the Faraday rotation angle (up to 10.8°=μm) within a special resonance peak of 12 nm (FWHM) linewidth at a wavelength of 772 nm, in …

Unidirectional Coupling Of Surface Plasmons With Ultra-Broadband And Wide-Angle Efficiency: Potential Applications In Sensing, Kun Li, Feng Xiao, Fan Lu, Kamal Alameh, Anshi Xu

Research outputs 2013

A cascaded-grating coupling scheme for unidirectionally coupling and launching surface plasmons from free-space light with ultra-broadband and wide-angle efficiency is proposed and theoretically investigated, and the potential applications in sensing are discussed. The cascaded sub-gratings of different periods couple the incident light over a relatively wide wavelength and angular range into surface plasmon polaritons (SPPs). After traveling a short distance, the SPPs interact with the sensed medium, and then are coupled back into freely propagating light through the nanoslit in the metal film. By observing the changes of SPP-mediated light coupled out through the slit, broadband sensing is achieved. A …

Surface Plasmons For Enhanced Metal-Semiconductor-Metal Photodetectors, Ayman A. Karar

Theses: Doctorates and Masters

Surface Plasmon Polaritons (SPPs) are quantized charge density oscillations that occur when a photon couples to the free electron gas of the metal at the interface between a metal and a dielectric. The extraordinary properties of SPP allow for sub-diffraction limit waveguiding and localized field enhancement. The emerging field of surface plasmonics has applied SPP coupling to a number of new and interesting applications, such as: Surface Enhanced Raman Spectroscopy (SERS), super lenses, nano-scale optical circuits, optical filters and SPP enhanced photodetectors. In the past decade, there have been several experimental and theoretical research and development activities which reported on …

Nano-Patterned High-Responsivity Gaas Metal-Semiconductor-Metal Photodetector, Ayman Karar, Chee Leong Tan, Kamal Alameh, Yong Tak Lee

Research outputs 2011

In this paper, we use the finite difference time-domain (FDTD) method to optimize the light absorption of an ultrafast nano-grating plasmonic GaAs metal-semiconductor-metal photodetector (MSM-PD) employing double metal nano-gratings. The geometry of the MSM-PD is theoretically investigated, leading to improved light absorption near the design wavelength of GaAs due to plasmon-assisted electric and magnetic field concentration through a subwavelength aperture. Simulation results show up to 8- and 21-times light absorption enhancement for the single and double nano-grating structure, respectively, in comparison to conventional MSM-PDs. Experimentally, more than 4 times enhancement in photocurrent is demonstrated for a single top nano-grating MSM-PD …

Absorption Enhancement Of Msm Photodetector Structure With A Plasmonic Double Grating Structure, Chee Leong Tan, Volodymyr V. Lysak, Narottam Das, Ayman Karar, Kamal Alameh, Yong Lee

Research outputs pre 2011

We present finite difference time domain simulation to analyze the optical absorption enhancement of metal-semiconductor-metal photo detectors employing double plasmonic grating structures. Simulation results show that the combination of a subwavelength aperture and double nano-structured metal grating results in up to 25 times enhancement in optical absorption, in comparison to MSM photodetector structures employing only a subwavelength aperture. This improvement of the absorption enhancement is due to the coupling out function of the bottom grating structure which distributes the light to both side of the subwavelength aperture.

Groove Shape-Dependent Absorption Enhancement Of 850 Nm Msm Photodetectors With Nano-Gratings, Narottam Das, Ayman Karar, Mikhail Vasiliev, Chee Leong Tan, Kamal Alameh, Yong Tak Lee

Research outputs pre 2011

Finite difference time-domain (FDTD) analysis is used to investigate the light absorption enhancement factor dependence on the groove shape of the nano-gratings etched into the surfaces of metal-semiconductor-metal photodetector (MSM-PD) structures. By patterning the MSM-PDs with optimized nano-gratings a significant improvement in light absorption near the design wavelength is achieved through plasmon-assisted electric field concentration effects. Simulation results show about 50 times light absorption enhancement for 850 nm light due to improved optical signal propagation through the nano-gratings.

Design Of High-Sensitivity Plasmonics-Assisted Gaas Metal-Semiconductor-Metal Photodetectors, Ayman Karar, Narottam Das, Chee Leong Tan, Kamal Alameh, Yong Lee

Research outputs pre 2011

In this paper, we use the finite difference timedomain (FDTD) method to optimize the light absorption of an ultrafast plasmonic GaAs metal-semiconductor-metal photodetector (MSM-PD) employing metal nano-gratings. The MSM-PD is optimized geometrically, leading to improved light absorption near the designed wavelength of GaAs through plasmon-assisted electric and magnetic field concentration through a subwavelength aperture. Simulation results show up to 10-times light absorption enhancement at 867 nm due to surface plasmon polaritons (SPPs) propagation through the metal nano-grating, in comparison to conventional MSM-PD.

Compensation Of Loss And Stimulated Emission Of Surface Plasmon Polaritons, Guohua Zhu

Electrical & Computer Engineering Theses & Dissertations

Surface plasmon polaritons (SPPs) have become in recent years an important research topic because of their interesting, physics and exciting potential applications, ranging from sensing and biomedicine to nanoscopic imaging and information technology. However, many applications of surface plasmon polaritons are hindered by one common cause—absorption loss in metal.

Over the years, numerous proposals have been made on how to conquer the plasmon loss. In this dissertation, (1) the known solutions to the loss problem by adding optical gain have been reviewed; (2) the properties of surface plasmon polaritons are studied theoretically, and the solution of the controversy regarding the …